NZ528096A - Structural frameworks of webs and therefor - Google Patents

Abstract

An elongate metal member for use as a brace between timber components, wherein the member is a tab ended substantially straight bodied elongate member with an elongate axis extending along its length between the tabs, and wherein each tab has at least one opening to receive, for tab fastening purposes to a timber component, a fastener to be penetrative of a said timber component, the cross-section of each tab being substantially planar when compared to the cross-section of the substantially straight elongate body which accounts for the majority of the length of the elongate metal member, and wherein each tab has substantially a general plane aligned with, angled to a side or angled to opposite sides of the elongate axis of the substantially straight elongate body, and wherein prior to and/or during tab fixing by said fasteners, at least substantially to the extent required by the timber component spacing and the length of the elongate body, to enable the tabs to lie with their general plane substantially parallel to the elongate axis of each said timber component, each general plane of a said tab can be articulated relative to the elongate axis of the substantially straight elongate body. (62) Divided out of 518135

Description

|A 5280 9 6 NEW ZEALAND PATENTS ACT, 1953 No: 518135 Itself divided out of Patent Nos. 337427/502650/504428 Date: 25 August 1999/28 January 2000/09 May 2000/02 April 2002 Intellectual Property Office of NZ - 8 SEP 2003 COMPLETE SPECIFICATION IV ^ «o+.

'Structural Framework and Webs Therefor" We, MiTEK HOLDINGS INC., of 300 Delaware Avenue, Suite 1704, Wilmington, Delaware 19801, a corporation duly organised and existing under band by virtue of the laws of the State of Delaware, United States of America do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: 1 STRUCTURAL FRAMEWORK AND WEBS THEREFOR BACKGROUND OF THE INVENTION The present invention relates lo a framework including reinforcing webs and to the reinforcing webs.

Structural frameworks of the typo to which the present invention generally relate arc typically found in buildings and commonly lake the form of trusses or braced wall panels. Trusses come in several forms with two typical forms being a pitched truss (e.g.f a roof truss) and a straight or parallel chords truss (e.g., a floor truss). Trusses are formed with chords having webs conncctcd thereto to reinforce the truss. Braced wall panels are similarly constructed, but used in an orientation where the chords or "beams" extend generally vertically. Over the years, webs have evolved from lumber cut lo shape and length and toe nailed into place. Later, such wooden webs were joined with nailing plates having integral nails. Currently, aJl melal webs with integral nailing plates pressed into the sides of the chords arc used to construct some trusses (particularly flat trusses). The evolution of webs and their securcmcnt has improved both the efficiency in manufacture and the structural integrity of the formed truss.

During the construction of trusses using wood webs and separate nailing plates or melal webs with integral nailing plates, the set up of the truss forming machine is time consuming and critical since it is necessary to set up the jig with reaction pads or pedestals for uso in driving the nailing plates into the webs and/or chords. Further, when the truss uses wood webs and separate nailing plates, each web has to be custom cut (although the webs may be mass produced to a unique configuration) and positioned by hand lo effect installation which is lime consuming and therefore costly. Further, as the pricc of wood has increased, melal webs have beoome more economically attractive. The metal webs that arc pressed into ihe sides of the chords, unlike wood webs that fit between inside edges of the cords, may sometimes make stacking of the trusses difficult because the webs have portions that project from the opposite faces of the chords. There is thus a need for an improved melal web tliat fits between inside edges of the chords like wood webs.

SUMMARY OF THE INVENTION Among the several objccts and features of the present invention may be noted the provision of a metal web that will fit between the beams of a structural framework; the provision of such a web that can be easily secured to the beams; the provision of such a web having a single configuration useable on a variety of frameworks with the same configuration; the provision of such web that can be economically made and used; and the provision of a structural framework utilizing such a web.

A metal web member of the present invention is preferably for use in a fabricated framework comprising at least two spaced apart beams with transverse thickness and having exterior surfaces and at least one web member securcd to the beams and extending between generally opposed exterior surfaces of the beams. The web member comprises a support section having transverse width substantially equal to or less than the transverse thickness of the beams and having opposite ends. A tab extending longitudinally from the support section at each end thereof has planar engagement surfaces. Each tab is sized and shaped for generally flat, facc-to-face engagement of its planar engagement surface with a respective one of the exterior surfaces of one of the beams for of the lab securcmcnt thereto. The tabs are further adapted to receivc a fastener through the planar engagement surface for the sccurement of the web member to the beams.

In another aspect of the present invention, a method of constructing a structural framework for a building comprises the step of providing first and second beams at least partially spaced apart, each beam having longitudinally extending exterior surfaces, At least one metal web is provided for interconnection between the first and second beams. The web has a support section and a tab extending outwardly from generally adjacent each end of the support section. Each lab is formed to have a planar engagement suvfacc and a fastener hole extending through the planar surface. Tho tabs at each end of the support section of the metal web are arranged for flat, face-to-face engagement with one of the exterior surfaces of a respcctivc one of the first and second beams such that the support section extends at an angle with respect to the first and second beams. The tabs are securcd to the beams by passing a fastener through the fastener hole of each tab and into said respective one of the first and second beams.

KFJ/mjc 3 In yet another aspect of the present invention, a tool for driving a scrcw through a web and into a beam of a structural framework for a building comprises a tool head having an engaging portion for engaging a head of a scrcw (o rotate the screw and drive the screw into the workpiece in a direction parallel to the longitudinal axis of the screw. A drive shaft is arranged transverse with rcspect to the intended direction of driving of the screw into the work piece. A drive transmission between the drive shaft and the engaging portion transmits rotary drive from the drive shaft to the engaging portion. The drive transmission is constructed lo limit the torque applied by the tool head to the scrcw.

In still another aspect of the present invention, a die tool forms a securing tab on a metal web to be used in forming a structural framework for a building. The die tool includes a bottom die tool having a squash block and a capturc block, the squash block being moveable relative to the capture block. A top die tool has a squash block moveable relative to a capture block. A guillotine block is movable relative lo the squash blocks and the capture blocks to cut the web. The web is retained by the capturc blocks and the squash blocks are moved relative to the capture blocks so as to squash the end of the web so as to form a flattened portion of the securing tab. The guillotine block is moved relative to both the capturc blocks and the squash blocks so as to cut lateral edge portions from the flattened portion of the securing tab.

Other objcct.s and features will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a standard pitched roof truss with four webs extending between the chords with ihc web members being of the general type shown in Fig. 5; Fig. 2 shows a truncated pitched roof truss showing the use of a pair of web members of the type shown in Fig. 11C; Fig. 3 shows a parallel chords truss illustrating the use of web members of the general type shown in Fig. 5; Fig. 4 is a perspective of a web member of the type shown in Figs. 1 OA-1 OH; Fig. 4A is a perspective of an adjustable length web member similar to the fixed length web member of Fig, 4; Fig. 4B is an elevation of a truss incoiporating the adjustable length web member of Fig. 4A; Fig. 5 is a perspective of a web member of the type shown in Figs. 11 A-l IF that provides a plurality of interconnected web member sections; Fig. 6 is an enlarged cross scction of a web member and insert taken along the line 6-6, Fig 5; Fig. 7 is an enlarged fragmentary side view of a web member of the type shown in Figs. 11 A-l IF; Fig. 8 is an enlarged fragmentary side view of a web member similar to Fig. 7 but showing a different shape of notch in a side wall; Fig. 9 is an enlarged fragmentary side view of a web member similar to Figs. 7 and 8 but showing a still different shape of notch in a side wall; Figs. 10A-10B arc side views of a range of different lengths of web members oflhc type dcpicted in Fig. 4, for example 600, 900, 1200,1800, 2100 mm long; Figs. 11 A-l 1F are side views of the type of web member with multiple interconnected sections of the type shown in Fig, 5 with section lengths of 600 plus 1200, 900 plus 1200,1200 plus 1200,1200 plus 1800,1200 plus 2100 and 1S00 plus 2100 mm long as examples; Fig. 12 is a perspective of a reinforcing member for use as shown in Figs. 13 and 14; Fig. 13 is an enlarged scction view of the web and reinforcing member taken along the line 13-13, Fig. 14; Fig. 14 is a perspective of a web member with an installed reinforcing member; Fig, 15 is an enlarged fragmentary si do view of the connection of web members to top and bottom chord members of a pitched roof truss; Fig. 16 is an enlarged fragmentary perspective of a pitched roof truss showing forward and reverse bends in the web member; Fig. 16a is a further enlarged fragment of Fig. 16, but showing a web member having an car lo augment attachment; Fig. 17 is a side elevation of a modified form of a web member made from a tube; Fig, 18 is an enlarged, fragmentary portion of the modified web member of Fig. 17 at a ccntral portion; Fig. 19 is an enlarged, fragmentary portion of an end of the modified web member of Fig. 17; Fig. 20 is a fragmentary portion of a web member configured for greater strength if of a longer span using a capping member; Fig. 21 is a side elevation with reference lo load direction (horizontal load direction) of a structure having limber studs braced by webs in accordancc with the present invention; and Fig. 22 is an enlarged, fragmentary perspective view of the arrangement showing part of the structure as shown in Figure 21.

Fig. 23 is a side view of a metal web for a building truss, shown broken in the middle, -according to an embodiment of the invention; Fig. 24 is a plan view of a left end of the web of Figure 23; Fig. 25 is a cross-sectional view along the line 25-25 of Figure 24; Fig. 26 is a view along the line 26-26 of Figure 25; Fig. 2CA is a plan view of an extension piece which can be used with Ihe embodiment of Figs. 24 to 26; Fig. 26B is a side view of the extension piecc of Figure 26A; Fig. 27 is a view of a building truss using metal webs of the type described with refcrcncc to Figs. 23 to 26; Fig. 28, 29 and 30 are enlarged, fragmentary views of portions of the truss of Fig. 27; Fig. 31A, 31B, 31C, 31D, 31E and 31F show various different tab configurations which can be used in the present invention; Fig. 31G is a plan view of a part of a web according lo a further embodiment of the invention; Fig. 31H is a side view of the part of the wob of Figure 31G; Fig, 311 is an end view of the part of the web of Figure 31G; Fig, 31J shows theweb o f Figure 31G applied to a chord of truss; Fig. 32 is an enlarged, fragmentary view showing one preferred manner of connecting a metal web lo a chord of a truss; Fig. 33 is a perspective viow of part of a metal web according to a further embodiment; Fig. 34 is a side view of a completed metal web according lo the embodiment of Figaro 33 Fig. 35 shows a still further embodiment of the invention; Fig. 36 is a perspective view of an extension and/or strengthen member used in one embodiment of the invention; Fig. 37 is a bottom plan view of the member of Figure 36; Fig. 38 is a side view of the member of Figure 36; Fig, 39 is a schematic cross-scctional view of a driving tool used to fasten the metal webs according to the preferred embodiment to a chord of truss; Fig. 40 is a view of a bottom die tool used in forming the metal webs according to Figs. 23 to 26; Fig. 41 is a cross-sectional view through the tool of Figure 40; Fig. 42 is a cross-sectional view along the line 42-42 of Figure 41; Fig. 43 is a perspective of a capture block used in the tool of Figure 40; Fig. 44 is a plan view of the capturc block of Figure 43; Fig. 45 is a perspective of a squash block used in the embodiment of Figure 40; Fig. 46 is a plan view of the squash block of Figure 45; Fig. 47 is a perspective of groove block used in the tool of Figure 40; Fig. 48 is a plan view of the groove block of Figure 47; Fig. 49 is a perspective of a top die tool (shown in an inverted position to that in which it would be used) which is used with the tool of Figure 40 to form a complete tool for forming metal webs according lo Figs. 23 to 26; Fig, 50 is a view of the top die of Figure 49 as shown in a compressed condition; Fig, 51 is a cross-scctiona] view through the die of Figure 50; Fig. 52 is a cross-sectional view through the line 52-52 of Figure 51; Fig. 53 A is a perspective view of a guillotine tool used in the top die of Figure 50; Fig. 53B is an end view of the guillotine tool of Figure 53A; Fig. 53C is a side view of the guillotine tool of Figure 53A; Fig. 53D is a plan view of the tool of Figure 53A; Fig. 54 is a view showing the commencement of the formation of a metal web of the typo shown in Figs. 23 to 26, using the tool formed from the die tools of Figui c 40 and Figure 50; Fig. 54A is a fragmentary elevation of the metal web in initial condition before formation from the tool as shown by Figure 54; Figs. 55 and 55A, Figs. 56 and 56A, Figs. 57,57A and 57B and Figs. 58 and 58A schematically show a sequcncc of operations of the tool of Figs. 40 and 50, and the web as it is being formed during those sequence of steps; and Fig. 59 is a view of a screw used in the preferred embodiment.

Corresponding reference characters indicate corresponding parts throughout ihe several views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The reference numerals 21A, 21B, 21C designate generally three different styles of truss, 21A being a pitched roof truss (Fig. 1), 21B being a truncated pitched roof truss (Fig. 2) and 21C being a parallel chords truss (usable, e.g., as a floor truss)(Fig, 3). Truss 21A comprises a pair of sloped top chords 23 joined at the apex 25 and a bottom chord 27 joined to the top chords 23 adjacent lower ends of the top chords with, nailing plates 31. The chords arc broadly referred to herein as "beams". The truss 21A is generally triangularly shaped. The truss 21B is similar lo the truss 21A except it has a truncated top formed by a horizontal top chord 35 extending between and securcd to the chords 23 with, e.g., nailing plates 31. The truss 21C comprises top and bottom chords 37,39 and can be provided with generally vertical end posts 41 secured to the chords 37,39 also with nailing plates 31. The chords 23,27, 35,37,39 have inside edges 23E.27E. 35E.32E. 39E at least partially defining interior spaces 43A, 4313,43C for the trussos 21A-C respectively, The width of the inside edges is the transverse thickness thereof and of the trusses. The chords 23,27, 35, 37, 39 and posts 41 also have opposite side faces 23S, 27S, 35S, 37S, 39S,41S respectively lying in generally parallel planes for each of the trusses. Preferably Ihc chords are wood, for example so-called 2X4's (nominally 1-1/2" X 3-1/2"). For the trusses 21A, 21B, the narrow surface (1-1/2") is typically the inside edge, while for a parallel chords truss 21C, the wide surfacc (3-1/2") is typically the inside edge. However, it is lo be understood that the chords could be made of metal without departing from the scope of the present invention.

A formed metal web member is provided and is securcd to and extends between at least two chords of a truss, Three forms of web members arc shown, the form in Figs. 10A-J Oil, the form in Figs. 11 A-l IF and the forms in Figs. 17 and 23, All forms have common features and will be first described in regard to the form shown in Figs, 4 and 10A-1OE, all being the same construction cxccpt for dimensions. A web member 51 includes an elongate bottom wall 53 having opposite ends and opposite side edges. Preferably, the wall 53 is generally planar. At least one side wall and as shown, a pair of side walls 59L, 59R extend upwardly from the wall 53 at the side edges and fonn a central support section 58, The walls 59 are generally parallel and preferably generally normal to the wall 53 and form an open sided channel with the wall 53. The walls 59 have opposite ends 61L, 61R that are preferably contoured as by rounding or in other suitable shapes, A fastening tab 63 extends from each of the opposite ends of the central support section, The tabs 63 have generally planar oppositely facing surfaces with one or more apertures 67 extending therethrough. The web member is preferably metal, e.g., steel, galvanized for rust resistance and has a suitable thickness such as about 0.85 mm. The width W of the tab 63 is approximately equal to or slightly less than the width of the inside edge of the chord to which the web member is to be secured. The length L of the tabs 63 is about 35rnm and their width is about 20mm in the illustrated embodiment. The spacing between the walls 59 is approximately equal to the width W of the tabs. The height of the walls will be determined by the rcsistancc to bending needed in web member and in one embodiment are in a range of about 50mm to 70mm. The web member 51 can be made from flat sheet material and cut to shape and then roll formed or bent on a brake to form the walls 59. When completed, die bottom wall 53 is generally planar as arc the walls 59 . The walls 53, 59 are one picce with each other and form an open ended channel.

An adjustable length web member 51' having a basic construction similar to the web member 51 of Fig. 4 is shown In Figs. 4A and 4B. Corresponding parts of the web member 5 V will be designated by the same reference numerals used for the web member 51 of Fig. 4, followed by a prime. The web member 51' includes two web elements 51 A' and 5 IB', each having the channel shaped construction of Fig, 4, but including a lab 63' at only one end. The web member 5 IB' is inverted from the position of web member 51 A' and inserted into the open end of the web member 51 A' opposite the end having the lab 63'. The overall length of the web member 51' is detennined by the lengths of the web elements 5] A' and 51B\ and how far element 5IB' is inserted into 51 A'. When the desired overall length is achieved, the web elements 51 A' and 51B' are secured together by pairs of sheet metal screws S driven through the bottom wall 53' of the element 51 A' and the bottom wall 53' of the element 51B'. Preferably a short piece of lumber L is placed in the overlapping scction of the web elements 51 A' and 5 IB' for enhancing the conncction of the screws S. Once the length is set, the web member 5 r is used in the same way as web member 51 for conventional trusses, as shown in Fig. 4B, or for wall bracing, The web member 51' has the advantage being able to be adjusted in length so that the angle of the tab 63' can be controlled so that it does not interfere with the end of the support section 58'.

The web member 71 (Figs. 5, 11A-1 IF and 14)is similar to the construction of the web member 51. The web member 71 is essentially a series of two or more connected webs 51 wherein a plurality of central support sections 58 are conncctcd together, The connection is provided by a common tab 03 attached lo and extending between adjacent end-to-end web central support sections. Two or more sections may be provided, A series of web members 71 are shown in Figs. 11 A-l IF, each being comprised of a connected pair of support sections 58. The truss of Fig. 3 illustrates a web 71 with four support sections 58 conncctcd by labs 63. The sections 58 may be formed separately and secured together but in Ihe preferred embodiment, are formed form the same picce of material, so that tho tabs <53 of adjoining sections arc not structurally distinct. Notchcs 73 (Figs. 7, 8 and 9) are defined by the adjacent contoured ends 61 of the sections 58 and allow bending of the labs 63 in both a forward direction (the ends 61L, 61R on opposite ends of a notch move closcr together) and a rearward direction (the ends 61L, 611< oil opposites ends of a notch move apart) for sccurcment of a web member to chords as described hereinafter. The notchcs 73 allow for easy bending at the tabs 63 and prevent interference between the ends of the walls 59 when the bend is a forward bend.

A modified form of web member is shown in Figs. 17-19 wilh parts similar to the parts of the web 71 being shown with a prime superscript for clarity. The web 71' is formed from a tube 81 wilh the tabs 63' being formed by deforming (flattening) a short length of the tube. An aperture 67' is formed in the tab 63'. In this embodiment, the sidewalls 59L', 59R' are the more upright portions of the perimeter of the lube. The bottom wall 53' is the lowermost portion of the tube perimeter. The web member 71' has a top wall portion 83 which is the uppermost portion of the perimeter of the lube.

Preferably, the tube is generally round in transverse cross scction cxccpt in the deformed areas forming the tabs 63'. However, the tube may have other cross sectional shapes, such as rectangular or oval, without departing from the scope of the present invention.

During loading of an open top (channel shaped) web member 51 or 71 in compression, the side walls 59L, 59R may deflect toward or away from one another. A slight inner directed curvaturc could be provided in the side walls lo induce inward deflection during compression loading. A reinforcing member 85 is provided to resist such deflection and is illustrated in Figs. 12,13,14. The reinforcing member 85 has a pair of flanges 87 conncctcd to and projecting generally at right angles from a central connecling wall 89. The outer surfaces 91 of the flanges 87 arc spaced to snugly fit between the inside surfaces of side walls 59 for a friction fit therebetween. The flanges 87 are each provided with an elongate outwardly opening groove 95 extending along the length of the member 85 at a position adjacent the junction between the ccntral wall 89 and the flanges 87, When a reinforcing member 85 is installed in a web member 51 or 71, the grooves 95 are adjacent free edges of the side walls 59. The flanges 87 have a height substantially equal to the height of the wall 59 so that an outside surface of the flanges is flush or slightly above flush with the free edges. The side walls 59 are bent lo form inwardly directed protuberances 101 (Fig. 13) that can be in the form of longitudinally extending ribs or localized ridges or dimples spaced along the length of the side walls. The protuberances 101 project into the grooves 95 for releasably retaining ihc member 85 in the support scction of the web member 51 wilh a snap lock connection. An aperture 105 can be provided in the central wall 89 for the attachment of laterally extending intcrtruss braccs or additional web members to sections (not shown) of the web member 71 or between web members 51 for additional bracing.

Reinforcing member 85 can be utilized once or at several different positions on longer spans. There may be a case for providing a more aesthetic box section for longer sections while at the same time providing a greater measure of rigidity. If desired the web member can be provided with, for example, the in turned flange type forms 59' depicted in Figure 20. These flange like forms 59' can be complemented by appropriate flanges 86 of a capping member 85' which can (if desired) run for the full extent or substantially the full extent of the web member. The flanges 86 bear against the llange like forms 59' to retain the capping member 85' in placc. it is within the scopc of the present invention lo connect the capping member 85' to the web member by fasteners or by welding (not shown), The side walls of Ihe web member of Fig. 20 arc formed with ribs 88 to further increase their strength.

Tn the construction of a truss, the various chords are joined together in any suitable manner to form the perimeter shape of the truss. The desired web member 51,71 or 71' is selected and the tabs 63' arc bent relative to the central support sections to overlie and engage the inside chord edges, e.g., 23E, 27E, for attachment at predetermined locations thorcalong. Referring to Figs. 15,16 and 16A, web member 71 is securcd to at least two chords by driving a fastener 107, such as a screw fastener, through each of the apertures 67, of the tabs 63. The fasteners 107 have enlarged heads 108 that each overlie a rcspcctivc tab. A washer 109 may be provided for each fastener 107 to help stiffen and strengthen the tabs 63, to reduce bending or fastener tear through and is capturcd between a respective head 108 and tab. The longitudinal axis of each of the fasteners 107 lies in a plane generally parallel to the plane of the respective yuss 21A-C formed by the chords.

The plane of a truss (Fig. 16) is a plane extending between opposite ends of the tmss and bisecting the truss between the opposite side faccs, e.g., 23S, 27S. Alternatively, the truss may be considered as including two planes, each including respective side faces 235,275 of the chords 23,27, The longitudinal axis of the fastener 67 is also generally parallel to the opposite side faccs, e.g., 23S, 27S of a chord into which Ihcy are screwed. If desired, additional fasteners may also be used to secure the side walls 59 of tho web members 51, 71 where they overlap the side edges of the chords. The lengths of the ccntral support sections of the web members are preferably sized so that the tabs 63, will be located on the chords at desired locations for appropriate bracing of the chords. The notches 73 can be formed by removal, e.g. culling, of material from Ihc sheet material from which the web member 71 is made. In an alternate embodiment, the sheet may be cut to form the end edges of the side walls 59 leaving the material conncctcd at one edge lo Ihc tab 63 to form an car II1 (see Fig. 16A) which may also be used lo help sccure the web member to a chord with an additional fastener 107. The car 111 is bent down over the side 275 of the chord 27 as shown in Fig. 16A. Such an arrangement would be useful when there is insufficient room in the inner space 43 lo use a fastener driver.

Referring now to Figs. 21 and 22, web members 51, 71 of Ihc present invention ave shown as employed in a wall frame 90 including a top plate 90a, a bottom plate 90b and studs 90c extending between the lop and bottom plates. Tn this embodiment, adjacent studs constitute the first and second beams. The web members 51,71 extend generally from side lo side instead of lop lo bottom as when used in trusses. The web members 51, 71 bracc the wall frame 90 against lateral or shearing forces oil a wall of a building, such as may be experienced during an earthquake or in high winds. The web members 51,71 may be secured to the studs 90c in ihc same way as they are secured lo the chords of the trusses described above.

With reference lo Fig. 23 a metal web 300 for a building truss T shown in Fig. 27 is closcly related to the metal web 71' shown in Figs. 17-19 above. The metal web 300 is formed from a melal lube 301 which is preferably of generally circular cross-section. The metal tube 301 may form a complete cylindrical structure and be formed in a rolling proccss with edges of the blank from which the lube 301 is foonpd.freing welded or otherwise joined together to form a tube 301 having a continuous circular or cylindrical wall. However, it is lo be understood that tubes (not shown) of non-circular cross section may be used without dqiarling from the scope of the present invention. In other embodiments the tube 301 can bo rolled so that edges of the blank from which the tube is formed arc merely adjacent one another without being joined together thereby forming a longitudinal slot which extends the length of the lube. The web 300 can be formed in stock lengths commencing at a length of 300 mm with stock lengths increasing in length by 150 mm up to a maximum length of2900 mm. These slock lengths arc merely exemplary and obviously other stock lengths and increments could be used if desired.

The web 300 has securing tabs 302 fonned al least at one end. In the preferred embodiment each end has a securing tab 302 as clearly shown in Fig. 23. The manner in which the securing tabs 302 are fonned will be described in detail-hereinafter with rcfcrcncc to Figs. 40 lo 58, The securing tab 302 comprises a generally flat tab portion 304 which has a hole 305 for receiving a fastening scrcw S (see Figs. 28 lo 30 for example), The tab portion 304 is formed symmetrically with respect to the cylindrical tube 301 as is best shown in Fig. 23.

The flat lab portion 304 merges into the tube 301 at a transition scction 306. The flat lab portion 304 is generally formed by diametrically opposed semi-cylindrical surface portions of the tube 301 by squashing or flattening those portions together as will be desoribed with reference to Figs. 40 to 58. The transition scction 306 comprises opposed valleys 308 which extend axially inwardly from the lab portion 304 and merge with a deformed pari 301a of the tube 301. Each valley 308 is located between a pair of ridges 309 (as best shown in Fig. 24) which incline outwardly from the tab portion 304 to the non deformed portion 301 a of the tube 301. As best seen in Fig. 24, the valleys 308 taper from a generally wide entrance portion 310 to a narrower end portion 311 wilh the entrance portion 310 being adjacent the tab portion 304 of the tab 302. Each pair of ridges 309 has side walls 312 which merge wilh the floor 307 of Ihe valley 308. The side walls 312 are joined by a curved transition wall 312a.

Ends of the ridges 309 adjacent tab portion 304 have sloping end surface portions 313 which slope down to Ihc tab portion 304, Tab portion 304 has a ncck 304a which projects inwardly lo Ihc enlrancc 310 of the valley 308 and Ihe floor 307 of the valley 308 inclines upwardly from the end of the neclc 304a lo Ihc wall 312. The walls 312 in cross-section transverse lo the longitudinal axis of the web 300 are slightly rounded so as to form a relatively smooth transition from the ridges 309 to the wall 312 and then into the floor 307 upon deformation of ihe lube 301 to form ihc valleys 308 and ridges 309, as best shown in Fig. 25.

As is clearly shown in Fig. 24 the tab scction 304 is no wider in the direction of double headed arrow W1 in Fig. 24 than the diameter of the tube 301. Thus the tab section 304 is within the confines of the tube 301 and does not project radially or diametrically beyond Ihc tube 301. This is important in the formation of building trusses because it enables the chords of the building truss lo bo the same size as the diameter of ihe lube 301, or alternatively, the tube 301 to be the same size as the chords of the building truss, so that the web 300, and in particular the tab portion 304, docs not project beyond the planes of the chords of Ihc building truss. This prevents interference wilh other framing or building components of a building to which the building truss is to be used and facilitates stacking. The manner in which the lab portion 304 is retained within the confines of the lube 301 so it does not project beyond the diameter of the lube 301 will also be described in detail with reference to Figs. 40 to 58, The transition between the flat lab portion 304 and the sloping surfaces 313 of the ridges 309 form a hinge line 314 along which the tab section 304 can bend relative to the lube 301 to angle the tab section 304 at a predetermined angle with rcspcct lo the tube 301 for flat, face-to-face engagement with a chord of a building truss.

Figures 26A and 26B show an extension piece 600 which can bo used wilh the embodiment of Figs. 23 to 26. The extension picce 600 is formed from a tubular member 601 which has an internal diameter slightly greater than the external diameter of the web 300 so that the tube 601 can slide over the web 300 (including the lab 302). The tube 601 is formed with a tab 602 which is identical in configuration to the tab 302 previously described except that it is slightly larger because of the slightly larger diameter of the tube 601. Tho lube 601 is provided with a plurality of holes 603 along its length and the lube 301 of Ihe web 300 can also be provided with a number of holes (not shown) along its length at least adjacent the tabs 302. Alternatively, the web 301 could be provided with a single hole. Tn still an alternative arrangement, the extension piece 600 could be provided with a single hole 603 and the tube 301 of the web 300 provided with a number of holes along its length adjacent the tab 302. In a most preferred embodiment, the extension piece 600 is provided with one or more holes 603 and the tube 301 has no holes. The extension piece 600 is located in the desired position on the tube 301 and a self tapping scrcw is driven through the hole 603, forming its own hole in the tube and securing the tube 301 and extension piece 600 in the desired position.

The extension piece 600 enables the length of the web 300 according to Figs. 23 to 26 to be adjusted by sliding the extension picce 600 over the lab 302 and onto the tube 301 of the web 300 at one of the ends of the web 301. The extension picce 600 is then secured in placc by locating a screw through one of the holes 603 of the extension piece 600 and into a hole in the tube 301 of the web 300 so as to sccurcly fasten the extension piccc 600 al the required position on the lube 301 to extend the length of the web 300 to a desired length. The extension piecc 600 may have a length of, for instance, about 400 mm. This embodiment of the invontion enables the length of the webs 300 to be extended by use of only a single piece and therefore decreases the number of stock lengths which may be required and also the number of components which are required in order to form a web 300 of a required longth. The extension piece 600 provides a substantially infinite adjustment of the length of the web 300 by sliding the extension piccc relative to the tube 301.

Fig. 27 shows a building trass T according to one embodiment of the invention which includes metal webs 300 of the type described with rcfcrcncc to Figs. 23 to 26. The truss T has a bottom chord T1 and upper chords T2 and T3 which are arranged at oblique angles with rcspccl lo the chord T1. Webs 300 extend between the chords T1 and T2 and T3 as shown. As best shown in Fig. 28 the tab portion 304 has been bent an angle of almost 90° so that it will lay flat against surface T3' of the chord T3. Figures 29 and 30 show details of how tab portions 304 are bent at desired angles so dial they will lay flat against the other chords T1 and T2 to enable securcmenl of the webs 300 lo the chords T1, T2 and T3.

The tab portion 304 is bent relative to the tube 301 by abutting the tab portion against part of the chord Tl and moving the tube 301 so as lo bend the tab portion about the hinge line 314. The wall thickness of the tube 301 is relatively thin and therefore the tab 304 itself is relatively thin and can bo bent relatively easily by manual force i f desired. In other embodiments the tab portion scction 304 could be already provided with a slight bend in one direction or the other so as to facilitate more easy bending of the securing scction 304 to the desired angle relative to the tube 301 for location flush with a chord Tl, T2 or T3.

As particularly shown in the more detailed Fig. 30, the webs 300 do not actually come into contact with one another or abut one another at positions where they meet the chords Tl, T2 or T3. In conventional wooden trusses it is usual that the wooden webs solidly abut and contact one another at positions where they arc joined to the chords Tl, T2 or T3. The reason for this is that the cont act of the webs with one another takes some of the load applied through the chords Tl, T2 and T3 and therefore distributes the load through both of the webs to or from the chords Tl, T2 or T3. However, in accordancc with the preferred embodiment of the present invontion the securing tab 302 is designed to operate in isolation in both compression and tension. The securing tab 302 which joins the webs 300 to the chords Tl, T2 and T3 is sufficiently strong to take all of the required load and therefore docs not require the webs 300 lo contact one another. Indeed, the webs can be spaccd apart at their connections with the chords Tl, T2 and T3 as is best shown in Fig. 30. Tho ability of being able to space the webs 300 from one another, rather than having them contact one another as in conventional wooden trusses, makes it easier to install the webs 300 in place and overcomes problems associated with precise lengths to ensure that webs do contact one another at the positions where they are joined to the chords Tl, T2 ov T3.

As previously described, the metal webs 300 are sccurcd lo the chords Tl, T2 and T3 by self tapping scrcws S which are driven through the holes 305 in the tab portions 304 and scrcw into the wooden chords Tl, T2 and T3. The preferred manner in which the self tapping scrcws S arc driven into tho chords Tl, T2 and T3 to sccurc tho webs 300 in placc will be described hereinafter wilh rcfcrencc to Fig. 39 and the preferred structure of the screws S will be described wilh reference to Fig. 59.

Figures 31A to 3 IF show various tab configurations which may be embodied in the invention. In these Figures, rather than the tab 302 being symmetrical wilh respect lo the lube 301, the tab 302 is formed to lie generally adjacent one peripheral portion of the tube 301 from which the web 300 is fonned. In Fig. 31A the lab 302 has the tab portion 304 formed as a right angle having portions 304b and 304c with the portion 304b being adjacont inside edge T3' of chord T3 and the portion 304c being adjacent side T3' of the chord T3. Tho tab 302 is secured lo the chord by a screw S passing through the opening 305 (not shown in Figs. 31A-31F) in the tab portion 304 and the side T3" into the chord.

Figure 31C shows tho web 300 of Fig. 3 IB but fixed in a position wilh the tube 301 rotated 180° about its longitudinal axis wilh respect to the lube 301 shown in Fig. 3 IB. It will be underslood that in Fig. 3 IB the web 300 lies entirely outside the planes of the chord T3' and in Fig. 31C the web lies entirely inside of the planes of the chord.

Figure 31D is a view similar to Fig. 31A except that Ihe portion 304b is somewhat shorter thereby locating Ihe tube 301 slightly higher relative to the chord T3 than the position shown in Fig. 31 A. Figure 31B is a view of a web 300 similar lo that shown in Fig. 31D exccpt located on the face of the chord T3 opposite to the face T3". In other words, Ihe configuration of Fig. 31D is simply rotated 180°.

Figure 31F shows an arrangement where the two opposed peripheral portions of the lube 301 which are compresscd together lo form the tab portion 304 are separated into two parts 304c and 304f so as to fomi a generally U-shaped channel configuration into which the chord T3 is locatcd. A pair of scrcws S pass through holes similar to the hole 305 in the separate portions 304e and 304f lo sccurc the web 300 to the chord T3.

The various embodiments with reference to Figs. 31A-31F show different tab configurations which can be used lo localc the web 300 at a desired position relative to a chord T3 should it be desired to provide the web 300 other than totally within the confines of the chords Tl, T2 and T3 to, for example, provide additional space for other framing or component which may be used in the building.

Figures 31G to 31J show a sti II further embodiment of the invention in which the tube 301 is formed with a tab 302 which comprises a first gusset 609 and a second gusset 610, The gussets 609 and 610 arc formed by slicing tho tube 301 substantially parallel wilh the longitudinal axis of the tube 301 and flattening the two sliccd portions of the tube 301 to form the gussets 609 and 610. Tlic portion of the tube 611 adjaccnt the gussets 609 and 610 is then deformed in a somewhat similar manner to that described wilh reference Figs. 23 to 26 so as to form a valley 615 on diametrically opposed sides of the tube 301 between tho gussets 609 and 610. The valley 615 inclines outwardly from the gussets 609 and 610 to merge with the undeformed part of the tube 301.

Figure 31IC shows the manner in which the web of Figs. 31G lo 311 is applied to a chord (for example the chord Tl). The gussets 609 and 610 arc applied over tho chord Tl so thai the gussets 609 and 610 sandwich the chord Tl. The gussets 609 and 610 are each provided with at least one hole 616 and screws S arc applied through the hole or holes 616 to join the gussets 609 and 610 to the chord Tl.

Figure 32 shows one embodiment of how the tab portion 304 is attached to a chord Tl. In this embodiment a washer 320 (substantially identical lo washer 109, described above) of generally square or rectangular configuration is utilized and which sits on Ihc tab portion 304. The lab portion 304 may have upstanding walls 321,322 and 323 which form a housing in which the washer 320 locates. The walls 321 may have flanges 326 which are bent over after location of tho washer. The walls 321,322 and 323 prevent rotation of the washor 320 as the scrcw S is driven into the chord TJ lo connect Ihe web 300 to the chord Tl. In other embodiments the lab 304 can be flat as described wilh reference to Fig, 23 and a separate box housing scction (not shown) could be located beneath the tab portion 304 for receiving the washer 320 lo hold the washer in place during driving of the screw S into the chord Tl. In these embodiments the tab 304 or the separate box housing retains the washer in the required orientation shown in Fig. 32, thai is wilh tlic washer parallel to the chord Tl so thai it does not spin or projcct outwardly beyond Ihe limits of the chord Tl, thereby speeding up assembly of trusses according to this embodiment of the invention.

As is cloarly shown in Fig. 32, the washer 320 is relatively thick and extends for substantially all of the length of the tab portion 304. Thus, ihc washer 320 extends from Die hinge line 314 described with reference to Fig. 24 lo the free end of the tab portion 304. The washer 320 provides additional strength to the connection of Ihe web 300 to the truss T and also additional strength of the tab 302. If the web 300 is tensioned, lhat is foroe is applied in Ihe direction of arrow F in Fig. 32, the washer 320 will resist Ihe tendency to lift the lab portion 304 from the chord T l at the position of the tab portion 304 which extends between the scrcw S and Ihe hinge line 314 which defines Ihc transition between the tab portion 304 and remainder of the wob 300.

Figures 33 and 34 shown an embodiment of the invention in which the web 300 is formed from a tube 301' as shown in Fig. 33. The ends of the lube 301' arc not deformed lo producc the tubs 302 previously described. Rather, in this embodiment, extension picccs 340 (see Fig. 34) are formed and have the tabs 302 formed at one end. The extension pieces 340 each include a sleeve into which a respective end of the lube 301' is inserted. The extension pieces 340 arc fastened in place by a screw 341 which passes through a hole (not shown) in the extension piece and also a hole 343 in the tube 301'. In this embodiment a number of holes (not shown) may be provided along the length of the lube 301' so lhat the web 300 can be adjusted in length by securing the extension piccc 340 to a desired one of the holes 343 or in a desired posilion along Ihe row holes 343 to provide a web 300 of a desired length. This embodiment has the advantage of being easily able to adjust the length of the web 300 wilh the disadvantage thai the web is formed from at least two different components thereby increasing the amount of stock required in order to form the web 300, Thus, this embodiment may rcduco the number of stock lengths which must be retained in order to form building tnisses at the expense of requiring additional components to form a completed web 300.

Figure 35 shows a further embodiment in which the web 300 has an auxiliary connection member 350. Tlic web 300 may be formed in Ihc manner described with reference to Figs. 23 to 26 with the securing tab 302 secured lo chord Tl (for example) in the manner previously described. In this embodiment washer 320 is merely located on top Intellectual Property of Ihe tab portion 304 and the scrcw S secures both the washer 32C#ft$30($fto^|rc chord Tl. The auxiliary connection portion 350 can serve cither or both of the functions of, extending the length of the wob 300 (in which case the tab portion 304 may not be securcd lo the chord Tl) and providing additional strength of the connection of the web 300 to the chord Tl, Tlic auxiliary connection portion 350 comprises a U-shaped scction 351 which has holes (not shown). Tho scction 351 may be semi-circular in cross scction and formed from a part tubular member. The scction 351 has a conncction tab 354 formed at one end by flattening out the section 351, or alternatively, by merely forming the section 351 into the curvcd configuration from a blank whilst maintaining the portion 354 in the flat configuration.

The tube 301 of the web 300 is provided wilh a row of holes (not shown) and the section 351 is conncctcd to the tube 301 by screws S2 which pass through the holes in scction 351 and locate in holes (not shown) in the tube 301. The portion 354 has a pair of holes (not shown) which receive screws S3 to attach the auxiliary connection member 350 to Ihe chord Tl.

Thus, if additional conncction strength of the web 300 to the chord Tl is required the web can be connccted by the securing scction 340 and the auxiliary connection member 350. If it is desired to increase the length of the web 300 then the connection member 350 can be coupled to the tube 301 at a desired position along the length of the lube 301. In lhat event, the web 300 would be connected to the chord Tl solely by the portion 354 and the scrcws S3.

Figures 36,37 and 38 show a further embodiment of an extension member or strengthening member 360. In this embodiment the member 360 lias a generally part tubular section 361 which has two opposed rows of holes 363 and 364 fonned along its length. At one end of the scction 361 a pair of connector paddles 365 are formed. The paddles 365 may be fonned by forming a cut along part of the length of the scction 361 and flattening out those parts of the scction to form Ihc paddles 365.

In this embodiment the remainder of the web 300 can be formed in the manner described wilh rcfercnce to Figs. 23 to 26 or simply from a tubular member 301' as shown in Fig. 33, The member 360 can be secured to the tube 301 bv sliding the tube into the U-shaped profile of the scction 361 and adjusting the position of the section 361 relative to Ihe tube 301 so that a desired one of the holes 363, 364 register wilh a hole at the end of the tube 301. A scrcw can then be inserted through the aligned holes to secure the member 360 to the lube 301. A member 360 can be attached to the other end of the tube 301 in the same manner if desired. The formed web 300 is then attached to a chord by locating the paddles 365 on opposed sides of the chord and hammering nails or driving a screw through holes 366 in the paddle members. This embodiment of the invention provides the ability lo extend the length of a web 300 and also additional strength because of the two paddle sections 365 which attach to the chord.

Figure 39 shows a driving tool 370 for driving the scrcws S through the holes 305 in labs portions 304 to connect the metal webs 300 to chords Tl to T3 of a building truss T. The tool 370 comprises a tool head 372 having a sleeve 374 which extends generally perpendicular lo Ihe axis of the screw S and the direction the screw S will be driven into the chords T. The sleeve 374 encloses a drive shaft 376. The drive sha/t 376 may be conncctcd lo a motor (not shown) for rotating the shaft 376. The motor may be contained within a housing having a suitable hand grip scction and actuation button for supplying power to the motor for rotating the shaft 376.

The shaft 376 has a bevel gear 377 attached to its end. The bevel gear 377 is contained within an upper cavily within the head 372. Tho bevel gear 377 meshes with a second bevel gear 379 also contained within the upper cavily. A socket 380 is rcccivcd in a middle cavity and is a generally snug fit in the middle oavity but having sufficient tolerancc to rotate within the cavily. The socket 380 has a neck portion 382 which is conncctcd to the bevel gear 379. The bevel gear 379, neck 382 and socket 380 may be fonned as an integral unit. The socket 380 has a socket recess 383 for receiving head H of the soiew S. The socket recess 383 has a magnet 385 is adhered or otherwise attached to tho closed end of the socket recess.

The cavily 379 is also in communication wilh u generally square shaped lower cavity. A magnet 386 is located in the lower cavity and is attached lo top wall 387 oTlho cavily. The lop wall 387 has an opening 388 which communicates the middle cavity wilh Ihe lower cavity and generally allows the screw S to pass through the cavity so the head H can be received in Ihe socket recess 383. The magnet 38(5 has a central opening 389 which registers with the opening 388 to also allow the scrcw S lo be rcccivcd in the socket recess 383.

Bottom surface 390 of the magnet 386 defines a surface against which washer 320 can sit. The screw S and washer 320 are formod from a ferromagnetic material and die magnet 385 serves to hold the head H of the scrcw S within the sockct recess 382 so that the head is retained above the washer 320 within the sockct recess 382. The magnet 386 holds the washer 320 within the recess 384. Thus, the screw S and the washer 320 can be applied to a hole 305 of a tab portion 304 to conncct the tab portion 304 to a truss chord Tl, T2 or T3 without the need of a workman to hold the screw S in place as the scrcw S is positioned and sorewed down into the chord T.

The distance between a lower extremity 394 of the socket 380 and the bottom snrfacc 390 is provided and dimensioned so as to prevent over tensioning of the scrcw S when the screw is driven into the chord Tl. If the screw S is over driven when it is applied lo Ihe chord Tl, T2 or T3 the over driving can strip out wood fibre from the chord and rcducc the offcctivc load on the connection screws. This can cause structural failure.

In the embodiments shown the bottom surfacc 390 of the magnet 385 spaces the washer 320 from the lower extremity 394 of the socket 380. However, if a greater spacc is required, or a smaller thickncss magnet used, a spacer member (not shown) could be located against the lower surface 390 of the magnet 386 provided that the magnet is still able lo provide sufficient magnet attraction to hold the washer 320 in the rccoss 384. The spaccr would have a ccntral hole similar to the magnet 386 to enable the scrcw S to pass into the socket recess 382.

Furthermore, it should be noted that the washer 320 is held in the required orientation in the square lower cavity so that when Ihe tool is applied to the scrcw S the washer 320 is parallel with the chord Tl and docs not projcct beyond the extremities of the chord Tl. Thus, the washer 320 will be applied to the chord Tl in the required orientation (such as that disclosed wilh reference to Fig, 32) without the need for manual intervention, thereby speeding up assembly of trusses.

As will be explained in further detail hereinafter, the over tensioning of the scrcw S into the truss chord Tl is prevented because when the screw S is rotated by the socket 380 and driven into the chord Tl, the screw S will eventually leave the sockct recess 382 and the head II will locate in the space between the lower extremity of tlic socket 380 and the top of the washer 320. The spaco between the lower extremity and the top of the washer 320 may be dimensioned to completely accommodate the head H so that the head H leaves the socket rcccss 382 or, alternatively, the space may be slightly smaller than the height of tho head H so that a small part of the head H still remains within the sockct rcccss.

When the screw S is to be applied to a portion 304 the tool 370 is actuated so as to rotate the shaft 376 to rotate the socket 380. Rotation of the sockct 380 will rotate the scrcw S. It should be understood that the washer 320 will remain in a fixed position within the rccess 384 because of the square shape of the recess 384 and corresponding shape of the washer 320. Thus, the screw is screwed down or into a timber truss chord TI duo to rotation of the scrcw S. As the sorew S is driven into the chord Tl, the bottom surfacc of the washer 320 will eventually contact the surface of the chord T into which the scrcw S is being driven. When this occurs continued rotation of the screw S will cause the scrcw S lo continue to be driven into the chord T with the head II beginning to leave the sockct rccess 382. When the head H abuts the top surface of the washer 320 the head H is accommodated within the space between the upper surface of the washer 320 and the lower extremity of the socket 380. If at this point the head H has completely left the socket rcccss 382 then obviously drive is no longer supplied to the screw S and therefore the screw S is not over driven into the chord Tl. In other words, as soon as tho head H screws down onto the top surface of the washer 320, the driving force or torque applied to the scrcw S is discontinued and therefore the scrcw is firmly screwed into the chord Tl but is not over driven into the chord Tl. 1 f the space between the lower extremity of the sockct 380 and the top of the washer 320 is such that the head H docs not completely leave the sockct recess 382, which is preferred, the head 382 will project only a very small distance into the recess 382 which is sufficient to provide driving torque lo the scrcw S to continue driving of the screw S when the head H contacts the lop surfacc of the washer 320. likaavmaLt of! the head js retained in the washer 326 it will simply be slightly rounded off by rotation of the socket 380 bccausc the engagement between the socket recess 382 and the head II is no longer sufficient to impart rotational torque to the screw S. The rounding off will not adversely effect the head II as it will be merely a slight rounding at the very uppermost portion of the head II. Thus, the integrity of the head H will remain in ease it is necessary or desired to unscrew the scrcw S from the chord Tl, The right angled configuration of the drive shaft 376 wilh respect to the screw S and driving direction of the scrcw $ is advantageous. This enables the head 372 to be positioned as close as possible lo the transition between tlic portion 304 and the tube portion 301 of the web 300, while keeping the axis at rotation of the sockct 380 perpendicular to the face of the chord Tl through which the scrcw will be driven. This, in turn, enables the hole 305 to be positioned as close as possible (o the tube 301.

Positioning of the hole 305 as close as possible to the tube 301 provides the advantage of reducing the bending moment which will be applied to the screw S during tension loading of the web 300. If the hole 305 is spaced a large distance from the lube 301 then the amount of leverage which will be applied to the screw S when tension is applied to the web 300 is greatly increased thereby increasing the possibility that the scrcw can be pulled out of Ihc chord Tl by lhat applied tension force. The right angled configuration of the head 372 enables the bead lo be positioned close in against the tube 301 and yel perpendicular to the adjacent facc of Iho chord, which may not bo possible in all circumstances if the tool 370 had a drive shaft 376 arc co-axial wilh the scrcw S, In such oases it may be ncccssary to position the screw S further from the tube 301, because of the confined space and interference wilh the tube 301 which may occur in some web configurations wilhin a building truss thereby providing the disadvantages discussed above, Figures 40 to 58 show a die tool for forming the labs 302 on webs 300 in accordance wilh the preferred embodiment of Figs. 23 to 26. The die tool comprises a bottom tool die 400 shown in Fig. 40 and top tool die 500 shown in Fig. 49. In use tlic top tool die 500 shown in Fig. 49 is inverted from the position shown in Fig. 49 and laid over the top of the bottom tool die 400 shown in Fig. 40 as will be shown in more detail with reference to Figs. 54 to 58.

With reference to Figs. 40 to 42 die 400 comprises a base plate 401. The plate 401 has bores 403 for receiving pins (such as pins 411) which arc used to locate components of the tool 400 and allow movement of the components relevant to one another as is usual in die tools. The base plate 401 also has bores 405. A squash block 406 (shown in more detail in Figs. 45 and 46) is mounted on the base 401 and retained in place by pins (nol shown) which locate in bores 403 and in corresponding bores in the block 406. The block 406 is fixed stationary relative lo the base 401 and therefore the pins serve only to hold the block 406 in place and not allow movement of Ihe block 406 relative to the base 401. As best shown in Figs. 45 and 46 the squash block has a raised squash surface 407 and a pair of lower surfaces 408. A groove 410 is formed in the block 406 from the squash surface 407 down to base 409 of the block 406. Returning lo Figs. 40-42, a capture block 412 is mounted for relative movement to plate 401 by springs 414 which locate in the bores 405 and which extend into bores 416 in the capture block 412. The springs 414 bias the capturc block 412 above the plate 401 as is best seen in Fig. 41.

As best shown in Figs. 43 and 44 the capture block 412 has an upper surfacc 417 which is provided wilh a semi-cylindrical groove or channel 418 which matches the profile of the tube 301 from which the web 300 is to be fonned. A groove 420 is formed in the capture block 412 and extends from the channel 418 to the base 421 of the capturc block 412. When the capture block 412 is mounted on the base 401 as sliown in Figs, 40 to 42 the groove 420 registers with the groove 410 of the squash block 406.

A groove block 425 which is best shown in Figs. 47 and 48 is inserted into the grooves 410 and 420. The groove block 425 is of generally monolithic configuration having side walls 427 and 428. The side walls 427 and 428 arc joined by an end wall 429 and a shorter rounded opposite end wall 430. An inclined valley forming surfacc 432 extends from the upper end of the wall 429 to the upper end of the wall 430. The configuration of tho surface 432 is the reverse of the configuration of the valley 308 which is made in (lie tab 302 of the web 300 formed by the surface 432, The surface 432 has a generally IJ-shapcd inclined wall portion 434 which will form thq^/kH24n&ter£L00 wall 312a of Ihc valley 308, a flat surface 435 which will form Ihc floor 307 of the valley 308 and a inclined end surface 438 which will form the surfaces 314 and entrance 304a of Ihc valley 308. When the groove block 425 is located into the grooves 410 and 420, the wall 429 is located in the groove 410 and the opposite end wall 430 is received in the groove 420.

Figure 49 shows the lop die tool 500. The top die tool 500 is similar to the bottom die tool 400 in lhat it has a base plate 501, a squash block 506 and a capturc block 512. The blocks 506 and 512 are configured the same as tho blocks 406 and 412 previously described cxccpt that the block 506 has only a flat squashed surface 509. A groove block 525 of the same configuration as the groove block 425 is Iocalcd in grooves 510 and 520 of the blocks 506 and 512 in the same manner as the block 425 is Iocalcd in the blocks 406 and 412 of lfig. 40. The lop die tool 500 is spaccd from the base plate 501 by a compression block 519 of polyurethane or like material. The compression block 519 also extends beneath and supports the squash block 506 as can also bo seen in Fig. 51. The block 512 is spaced from the plate 501 and Ihe block 519 by springs 514 as best shown in Fig. 51. It should understood that the configuration shown in Fig. 49 shows the springs 514 completely compresscd with the block 512 silling on the compression block 519.

A guillotine block 550 is fixed to the base plate 501 and surrounds Iho squash block 506. As best shown in Figs. 53A, 53B, 53C and 53D the guillotine block includes side walls 521 and 522 and end wall 523. The walls 521,522 and 523 generally form a U-shaped configuration as best shown in Fig. 53D so the guillotine 520 can be positioned about the squash block 506 as best shown in Fig. 49. The walls 521 and 522 carry knife edges 560 and 561 at their upper extremities. The knife edges 560 and 561 arc inclined wilh Ihe knife edge 560 inclined upwardly from wall 523 to end 562 and the knife edge 561 inclined downwardly from wall 523 to end 563. The walls 521 include bores 555 for receiving pins (not shown) to sccure the guillotine block 520 to the base plate 501. Once again, the guillotine block 520 is positioned in place without the need for movement relative to the plate 501. As shown in Fig. 49 tlic squash block 506 has a central bore 570 which loeates a tubular punch 571. When the squash block 506 and capture block 512 arc ill their starling positions where Ihcy are biased away from base plate 501 by the springs 514, Ihc punch 571 is retained within the bore 570, When the blocks 506 and 512 are in their fully compressed condition, when not only the springs 514 are fully compressed but the compression block 519 is also fully compressed, the punch 571 projects out of the block 506 as can be seen in Fig. 50.

The scqucncc of operations for forming the labs 302 of the webs 300 shown in Figs. 23 to 26, will bo described wilh reference lo Figs. 54 to 58. In order to configure Ihe tool shown in Figs. 40 to 53, the top die tool 500 is inverted from the position in Figs. 49 and 50 and arranged above the tool 400 as shown in Fig. 54. The plates 401 and 501 arc conncctcd to a press machine (not shown in the drawings).

As shown in Fig. 54, the unformed lube 301 (Fig. 54A) which is lo be used to form the web 300 is inserted into the cylindrical cavily defined by the two grooves 418 and 518 in the capturc blocks 412 and 512. In the position in Fig. 54 tho blocks 512 and 412 are biased away from their respective plates 501 and 401 by springs 514 and 414 (which arc not shown in Fig. 54 for ease of illustration). Tn this configuration Ihe groove blocks 425 and 525 are retained fully within the grooves 410,420 and 510, 520 respectively.

Similarly, the knife edges 560 ajnl 561 of the guillotine 520 are retracted from (that is above in Fig. 54) the squash surface 509 of the squash block 506, Figure 54A shows the tube 301 in this position where the tube 301. has not yet been actcd upon and is in its original condition.

Figure 55 shows first movement of the plates 501 and 401 towards one another under the influence of the pressing machinc (not shown) so as to capturc tho tube 301 (Fig. 55A). In this position the tube 301 is still not acted on but is merely captured and lightly held within the cylindrical space defined by the grooves 518 and 418. Continued movement of Ihe pressing machinc will cause the springs 514 and 414 to begin to comprcss allowing the capturc blocks 412 and 512 to move towards their respective base plates 401,501. This movement moves the capture blocks 412 and 512 relative to their respective groove blocks 425 and 525 so the groove blocks now begin to project into the cylindrical space defined by the channels 418 and 518 through the grooves 420 and 520 and work on the lube 301. Simultaneously, the squash blocks 406 and 506 also begin lo project beyond the capture block and begin lo squash the end of the lube 301. As shown iii Figs. 56 and 56A this begins to form the end of Ihc tube 301 to commence formation of the tab 302. The squash blocks 406 and 506 are beginning to squash the end of the tube 301 to form the tab portion 304 of the tab 302 and the groove blocks 525 and 425 are beginning to form the valley 508 and ridges 509 of the tab 302. It will be understood at this stage of operation the guillotine knife blades 560 and 561 are still rclractcd behind the surfacc 509 of the squash block 506.

Continued movement of the press machine brings the base plate 401 against the bottom of the capturc block 412 so that springs 414 are fully compressed. Similarly, the oaplurc block 512 is now resting on the compression block 519. This movement has brought the squash surfaces 509 and 407 of the blocks 506 and 406 fully together lo squash the end of the lube 301 to form the tab portion 304 of the tab 302. In this position the guillotine blades 560 and 561 as well as the punch 571, arc still retained behind Ihe surfacc 509 of the squash block 506. It will be apparent from the consideration of Figs. 57A and 57B that in the squashing of the end portion of the tube 301 to form the tab portion 304, bulges 304g are formed at the side edges of the flat tab portion 304. As will also be apparent from the consideration of Figs. 57 and 57A, the groove blocks 425 and 525 now project into the cylindrical space formed by the grooves 420 and 520 to their maximum extent thereby fully forming the valley 308 and ridges 309 of the tab 302.

As shown in Fig. 58, continued movement of the press machine will begin to move the base plate 501 relative to the capture block 512 and squash block 506 by compressing the compression block 519. As the compression block 519 is compressed, tho guillotine 550 and the punch 571 are moved relative to the squash block 506 so lhat the knife edges 560 and 561 are brought down lo bear on the flat securing section 304 of the tab 302 adjacent the bulges 304g thereby slicing the bulges 304g from the flat tab portion 304 to only leave the flat securing scction 304 as shown in Fig. 58A Simultaneously, the punch 571 punches the hole 305 through the tab portion 304 as it is driven out of bore 570 in the squash block 506. It should be understood that the step or space provided between the squash surface 407 of the block 406 and Ihc surfaces 408 provide room for movement of the knife blades 560 and 561 of the guillotine 520 and also a accommodate the bulges 3G4g which arc formed during flattening of the tube 301 by the squash surfaces 407 and 509. The press machine can then be released to retract the plates 501 and 401 away from one another so lhat the fonned web 300 can be removed.

As will be apparent from (he above description of the manner in which Ihe securing tab according to the embodiment of Figs. 23 to 26 is fonned, the formation of the valley of the valley 308 by the groove blocks 425 and 525 has the effect of pushing material down towards the center of tho tube thereby preventing outward expansion of the lube at this pari of Ihe web during flattening lo form the tab portion 304. Slicing of tlic bulbous or lateral edge portions 304g from Ihe edges of the flattened portion 304 has llie effect of ensuring this part of Ihe formed securing tab does not extend beyond the periphery of the tube 301 of the web 300. Further still, rcmovalof the bulges 304g takes away a considerable amount of material from the side edgos of the tab portion 304 and therefore makes it easy to bend the tab portion lo the required position so lhat Ihc tab portion can rest flat against Ihc required surface of a chord as described wilh reference to Figs. 21 to 30. If the bulges 304g are left in place not only will this mean lhat the securing tabs would extend beyond the periphery of the tube 301 but also a substantial mass of material is left which would make it very difficult, if not impossible, to bend the flattened tab portions 304 to the required angle so that they can sit flush against the chords of a truss during assembly of a truss.

In the preferred embodiment of the invention the tab portion 304 is bent during assembly of the truss without the need for any tool. The tab portion 304 can be bent by pushing an end of the tab portion 304'against the chord and then applying a force lo Ihc web 300 so as lo causc the tab portion 304 to bend. Altemalivcly, the tab portion 304 can be bent by application of the screw S through the tab and into the chord so that as the screw S is driven into the chord the screw S contacts the tab portion to bend the tab portion into the desired configuration. If desnred, the tab portion 304 can be provided with a slight bend to facilitate the further bonding of the tab portion cither by application of the screw or by force applied to the web 300 and engagement of the lab portion with the chord.

Thus, according to the preferred embodiment of tlie invention no tool at all is required in order lo bend the tab portion 304 thereby simplifying assembly and reducing Ihc cost of assembly because of Ihe need not to provide any particular tool to bend (he tab portion. In practice, a single pressing machine may carry a number of die tools of the type described wilh reference to Figs. 40 to 58 so that a number of webs 300 arc fonned in a single operation. Furthermore, both ends of the web 300 can be formed within the press machinc or in separate press machines simultaneously so as lo form the entire web 300 in a single operating sequence.

Figure 59 shows the preferred structure of a scrcw S used in the embodiments previously described. The screw S has a hoad H including an integral flange or washer portion H1 and a shank S' which is scrcw threaded in a convontional manner. The shank S' and its screw threading is of the conventional self lapping slyle. The shank S1 joins wilh Ihc flange 11' of the head H by a transition section 650 which tapers outwardly so as to form a region of increased thickness 651 between the shank S' and the washer portion H' of Ihc head H. This increases strength of the transition between the head 11 and shank S, preventing breaking of the head H from the shank S' when load is applied to the screw S. In conventional screws the shank S joins with the head H at a generally right angle step transition with no variation in Ihickncss that Ihe transition between the shank S and the head II. Thus, the head H is susceptible to breakage under load.

When introducing elements of the present invention or the preferred cmbodimenl(s) thereof, the articles "a", "an", "Ihe" and "said" arc intended to mean lhat there are one or more of the elements. The terms "comprising", "including" and "having" arc intended lo be inclusive and mean lhal there may be additional elements other than the listed elements.

In view of the above, it will be seen lhat the several objects of the invention arc achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims (6)

WHAT WE CLAIM IS:

1. An elongate metal member for use as a brace between timber components, wherein the member is a tab ended substantially straight bodied elongate member with each tab having at least one opening to receive, for tab fastening purposes to a timber component, a fastener to be penetrative of a said timber component, the cross-section of each tab being substantially planar when compared to the cross-section of the substantially straight elongate body which accounts for the majority of the length of the elongate metal member, and wherein each tab has substantially a general plane aligned with, angled to a side or angled to opposite sides of the elongate axis of the substantially straight elongate body, and wherein prior to and/or during tab fixing by said fasteners, at least substantially to the extent required by the timber component spacing and the length of the elongate body, to enable the tabs to lie with their general plane substantially parallel to the elongate axis of each said timber component, each general plane of a said tab can articulated relative to the elongate axis of the substantially straight elongate body.

2. An elongate member as claimed in claim 1 wherein said substantially straight body is tubular.

3. An elongate member of claim 2 wherein each tab has been formed from the tubular material of which the substantially straight body is still comprised.

4. The use of a member of any one of the preceding claims to brace two wall studs. 284666-1 -32-

5. An elongate member of any one of the preceding claims wherein the substantially straight elongate body is of annular cross-section and the tab ends have a width equal to or less than the width of the annular cross-sectioned body.

6. An elongate member of any one of the preceding claims wherein the substantially straight elongate body is adjustable insofar as its length is concerned. 284666-1