AU735271B2 - Fastener system - Google Patents

Description

-1- P/00/01 1 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT *r Invention Title: Fastener System The following statement is a full description of this invention, including the best method of performing it known to us: GH REF: P25097D:GS:CI -2- FASTENER SYSTEM BACKGROUND OF INVENTION This invention relates to fastener systems and fastener elements with particular application to the fastening of cladding sheets to support members.

While the invention is described in relation to the fastening of roof cladding and more particularly to roof cladding formed of sheet metal material, the present invention is not limited thereto and is equally applicable to fastener systems for other products, including walling, decking and other cladding, formed of sheets of metal, plastics or other material.

Traditionally, sheet metal roof cladding comprises a plurality of corrugated sheet metal sheets laid side to side 15 with overlapping edge margins. The sheets are generally fastened to transversely extending spaced apart battens, purlins or other support members by nails, screws or other fasteners piercing the sheets and engaging the battens.

In more recent times, "flat" or "ribbed" cladding 20 sheets have been developed. These sheets generally comprise oeeeo: an essentially flat web, often referred to as a "pan", having upright flanges along each longitudinal edge. Often the web includes one or more longitudinally extending upwardly directed stiffening ribs.

In roof structures these sheets are laid side to side with the flange of one sheet overlapping that of an adjacent sheet. Each sheet is generally provided with one edge flange in the form of a male rib formation and the other edge flange in the form of a female rib formation. In assembly, the male rib formation is adapted to fit snugly within the female rib formation in interlocking engagement to resist separation of the sheets in directions both normal to and along the longitudinal direction of said formations.

These sheets are generally fastened to battens by means of traditional fasteners or by concealed clips. Concealed clips are generally affixed to the battens, and overlaid by S:P25097D/493/14.11.97 3 the sheets. The clips present an upwardly directed projection adapted to fit and snap engage with the underside of the sheet ribs.

While concealed clips provide a roof structure with a uniform appearance devoid of unsightly fastener heads, they also ensure the integrity of the sheets is not compromised by fastener clearance apertures inherent in traditional fastener systems. Disadvantages of concealed clip construction include the high costs of construction due to the need to use relatively high skilled labour; the time consuming nature of the installation process including the steps of accurately positioning and affixing the clips to the support members, correctly aligning the flanges of the S. sheets with respect to the clips and ensuring that the 15 jointing therebetween is well made; and by virtue of the **inherent nature of conventional concealed clip snap-fit jointing, it has been found that under extreme weather conditions, joints of this kind generally offer insufficient strength to prevent the sheets from disengaging from the 20 clips. In areas subjected to high wind, cyclonic or other extraneous load imposing natural phenomena, high capacity fastener systems are required to resist such loads.

These generally comprise fastening systems utilising fasteners having a head and a shank, in which the shank extends through an opening in the sheet and into or through an opening in the support member to hold down the sheet.

Disadvantages of conventional high capacity fastener systems include the presence of the inherent fastener openings which pierce the sheet and thus enhance susceptibility to leakage, scratches formed on the sheet by skidding of the tip of the fastener or drill bit as the openings are produced which generally break the integrity of the protective corrosion resistant coating generally applied to sheet metal cladding thereby enhancing susceptibility to corrosion, and other difficulties generally arising from the production of openings, such as, for example, fastener or ":P25097D/493/14.I1. 97 4 drill bit skewing, generally attributable to the prerequisite that openings be located along the crest of ribs generally formed in cladding elements, and the resultant provision of multiple start points on the surface of the sheet, and the problem of inaccurate positioning of the opening in the sheet, the openings often being formed in misalignment with the support member by only a short distance, in the order of a few millimetres. This often requires replacement of the entire sheet thereby adding to the overall costs of installation, or plugging the opening. Plugging of such openings is not always a viable alternative to replacing the sheet, it being visually obtrusive and unacceptable in most building applications.

An object of the present invention is to provide a fastener system and fastener elements which will address one or more of the above mentioned disadvantages and/or desiderata.

oo SUMMARY OF THE INVENTION eo .According to the invention there is provided a cladding oo.. 20 sheet mounting element for use in fastening a cladding sheet to a support member, said element having a body with at least an upperside and at least an underside, said body being *provided with at least one fastener clearance aperture *o extending from said upperside to said underside wherein at 25 least a portion of said underside is adapted to make contact with the cladding sheet and at least a portion of said S: portion is provided with adhesive means.

S"It is preferred that the adhesive means is of sufficient tackiness to enable the element to be at least temporarily releasably affixeable to the sheet.

Preferably said at least a portion of the underside conforms to or complies with the shape and configuration of the surface of the cladding sheet with which it is adapted to make contact.

It is preferred that the element is in the form of a saddle adapted in use to straddle an upstanding rib of the S :P25097D/493/14 .11.97

I

5 sheet with the fastener clearance aperture in register with a crest of said rib.

Preferably the underside of the element is shaped to fit neatly over the crest and edge margins of the crest.

Preferably the upperside of the element is provided with a boss having a generally planar or flat upper portion.

It is preferred that at least a portion of the underside defining an edge margin of the underside encircling the fastener clearance aperture is provided with said adhesive means.

Alternatively or additionally a portion of the underside defining a band encircling the fastener clearance aperture disposed away from the aperture may be provided with said adhesive means.

15 The invention also provides a method of attaching a .sheet of cladding to a support member comprising the steps of: providing a fastener having a head and a shank with a tip; providing a cladding sheet mounting element having a body with at least an upperside and at least an S"underside, said body being provided with at least one fastener clearance aperture extending from said upperside to said underside wherein at least a portion of said underside is adapted to make contact with said cladding sheet and at least a portion of said portion is provided with adhesive means; emplacing the cladding sheet mounting element at a requisite disposition on the cladding sheet so that it is at least temporarily releasably affixed thereto by the adhesive means; then emplacing the tip within the fastener clearance aperture; and driving the fastener so as to drive the tip and shank through the aperture and into the sheet thereby piercing the sheet, through the sheet and into a S:P25097D/493/14.11.97 6 support member until the fastener is homed down.

It is preferred that the method comprises the further step of providing a sealing washer on the shank of the fastener prior to step It is also preferred that the fastener is homed down so that the head bears against the upperside of the element.

Preferably the head of the fastener is provided with an annular recess to accommodate at least in part the sealing washer.

More preferably said recess is defined by the shank of the fastener and a skirt depending downwardly from and integral with the head of the fastener.

In use the underside of the element may be emplaced at 15 a predetermined position in contact with an upper surface of the sheet. Generally the predetermined position may be on the crest of a rib of a cladding sheet and the element may be emplaced to straddle the crest with the nominal centre of the aperture in substantial alignment with the crest of the 20 sheet. The adhesive means may make contact with the upper surface of the sheet and the element may be temporarily releasably affixed thereto by said adhesive means. The bond may be of sufficient strength to minimise or prevent accidental radial movement of the element. A tip of a self tapping screw fastener may then be emplaced within the fastener clearance aperture of the element with its tip generally in register with the nominal centre of the aperture. The shank may be held so that its longitudinal axis substantially coincides with a line perpendicular to the plane of the sheet then the head of the fastener may be rotated and the tip directed downwardly into and through the sheet thereby piercing the sheet and engaging the underlaying support member.

Radial slippage of the tip of the fastener may thus be confined within the boundary of the aperture.

In the same way, in embodiments in which a drill is S:P25097D/493/14.11.97 7 used to pierce an opening in the sheet, radial slippage of the tip of a drill bit may be confined within the boundary of the aperture.

If it is found that the fastener does not enter the support member and that misalignment has occurred the element may be disengaged and moved along the crest to a corrected position. The distance that the element can be displaced and still effect sealing of the erroneously formed opening may be limited only by the length of the element.

By virtue of being adhesively secured to a portion of the cladding sheet, the element may, in effect, increase the thickness of that portion of the sheet and the element may provide the sheet with a portion of enhanced strength and rigidity, it may minimise the risk of excessive tearing 15 during piercing by impact drivable fasteners, self tapping screw fasteners or other piercing means, may limit radial displacement of the tip of the piercing device during piercing and/or tapping and assist in locating and guiding drill bits.

BRIEF DESCRIPTION OF DRAWINGS By way of an example, an embodiment of the above described invention is described in more detail hereinafter with reference to the accompanying drawings.

Figure 1 is a schematic perspective view of an embodiment of a mounting element according to the invention; Figure 2 is an enlarged view of a cross-section of an embodiment of a fastener and sealing ring according to one aspect of the invention; and Figure 3 is an enlarged view of a cross-section of important components of an embodiment of the invention in which a fastener, sealing ring and mounting element are emplaced with a roof cladding sheet on a support member in a secured but not fully tightened position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The cladding mounting element 6 illustrated by figure 1 may be formed of a coated steel sheet.

,P25097D/493/14 .11. 97 8 The illustrated roof cladding 1 comprises a coated steel sheet having a centrally disposed longitudinally extending upstanding rib formation 2 having a crest or crown 3 with bordering edge margins 4, 5 on each side thereof.

The cladding sheet is typically formed from a strip of 0.42 mm base metal thickness (BMT). The cladding sheet may be produced by roll forming. Other methods include stamp pressing and progressive stamp forming. The element is typically formed of the same material and produced by stamp pressing or other forming methods.

The mounting element 6 has an underside shaped and configured to conform to or otherwise comply with the shape of the crest 3 and bordering edge margins 4, 5. The underside of the element 6 is thus concavely curved in transverse section. The length of the element 6 is typically twice or three times its width so that the element 6 extends along the crest a considerable distance, typically in the order of 40 millimetres. The element 6 is provided with a centrally disposed fastener clearance aperture 18, extending from the upperside to the underside of the element 6, having a diameter closely associated with diameter of the shank 10 of a headed fastener 8 typically used as a high capacity roof cladding fastener. The diameter is typically in a range of 7.5 millimetres to 8.0 millimetres.

The underside of the element 6 is provided with adhesive means in the form of a firm adhesive 20 such as for example commercially available firm acrylic adhesive which has sufficient tackiness to enable the element 6 to be at least temporarily releasably affixed to the cladding sheet i. That is to say, the element 6 is releasably adherable to the cladding sheet 1 so that if the fastener 8 pierces the sheet 1 at an incorrect location not in register with a support member 16, the element 6 can be removed and relocated at a corrected position without substantial loss of adhesive and/or subsequent adherence of the element 6 to the sheet i. The adhesive means is also of sufficient S: P25097D/493/14 .11. 97 9 tackiness to substantially prevent movement of the element 6 during the piercing operation. In the illustrated embodiment a thin film of said adhesive 20, typically 0.1mm thick, is coated on the underside of the element 6 to cover a major portion of the underside of the element 6 and in particular that portion defining an edge margin of the underside encircling the fastener clearance aperture 18 and extending away from the aperture 18 to an edge margin of the outer periphery of the element 6.

The combination of adhesive means and conforming shape enables the element 6 to be easily positioned on the crest of rib 2 and be held in place prior to and during piercing of the sheet i.

The fastener clearance aperture 18 provides a guide for 15 the tip 20 and shank 10 of the fastener 8 and prevents the tip 20 from excessive radial movement during tapping.

Slippage of the fastener tip 20 is minimised thereby reducing any scratching of the surface of the sheet 1 by the tip or at least confining such scratching within the boundary of the edge of the fastener clearance aperture 18, S"which when the fastener 8 is tightened and the assembly homed down, is sealed or at least not exposed to the weather thereby limiting corrosion and oxidation.

The screw fastener 8 shown in figures 2 and 3 has a hexagonal head 9, a skirt 13 and a shank 10. The shank is provided with external threaded portions 11 and 12 and a tip 20. The skirt 13 is in the form of an outwardly projecting flange having a downwardly facing annular recess The recess 15 is adapted to ensconce at least a portion of a sealing washer made of a resilient material such as polyethylene or rubber or of other elastomeric material.

The sealing washer is typically in the form of an annular elastomeric washer 14 which is a tight fit on the shank 8 so that it can be preassembled therewith. The illustrated recess 15 is of rectangular cross-section, but in other embodiments it may be otherwise upwardly channelled.

S:P25097D/493/14.11.97 10 In use, the element 6 is emplaced along the outer face of the crest 3 of the sheet 1 with the nominal centre of the aperture 18, the apex of the crest 3 and the support member in the form of a purlin 16 disposed beneath the sheet 1 substantially in register. The adhesive means 20 contacts the sheet 1 and releasably holds the element 6 to the sheet 1. The tip 20 of the screw fastener 8 is brought into contact with the sheet 1 at the nominal centre of the aperture 18 and the fastener 8 is then driven downward under rotation to drive the tip 20 and shank 10 through the sheet 1 and into the purlin 16. The fastener 8 is then tightened by rotation so that the skirt 13 bears against the upperside of the element 6 with the washer 14 encased within the recess 15. The skirt 13 restrains the washer 14 from 15 extruding laterally as the fastener 8 is anchored.

Additionally, fastener 8 is prevented from being over tightened by the metal to metal contact between the peripheral edge of the shirt 13 and the upper surface 7 of S-the element.

An improved seal is effected between the screw fastener 8 and the element 6 by the above described fastener system.

The system enables the surface of the upperside of the element 6 defined by a substantially flat boss 7 to be brought into sealing contact with the underside of the skirt 13.

As "o-ring" washer 14 is small and the surface of boss 7 is substantially parallel with the underside of fastener 8, washer 14 is able to be captured within recess 15 and prevented from being squeezed out during installation. As fastener 8 is tightened against element 6 the washer is captured for the life of the connection thereby ensuring that the pierced opening is not exposed to the elements.

Furthermore the element 6 guides fastener 8 during insertion thereby minimising damage to the surface of the rib by minimising fastener tip and, where applicable, drill bit point skids. The element 6 also restrains swarf S:P25097D/493/14.11.97 11 produced during drilling, which normally can leave rust stains on metal sheets.

The adhesive means also functions as a long term seal between the underside of the element 6 and the cladding sheet 1.

Thread 11 on shank 10 ensures that the fastener 8 and element 6 form a mechanical sandwich relationship with washer 14 and maintains a seal under all roof service conditions.

A further advantage of the provision of the element 6 in roof fastener systems is that if an installer pierces the sheet 1 in the wrong place it is possible to move element 6 slightly and cover the mispierced opening with the element 6 before repiercing in a corrected position.

15 The upper surface of the element is provided with a boss 7 having a portion of flat form to provide both strength and a good sealing surface.

The shaping of the underside of the element 6 in that -manner also enables the element 6 to function as anti rotation means to more accurately position the fastener and retain it in position. This shaping also results in less deflection of the joint under load, by comparison with conventional arrangements wherein a substantial area of the underside of washers do not engage the sheet, and extraneous loads are transferred directly to the fastener assembly along the rib. This in turn provides greater hold down strength than would otherwise be the case. Because a larger area the underside conforms to the sheet than generally provided by conventional systems it has been found that the element 6 not only provides additional strength to the roof assembly as a whole but also enables a much larger hold down force to be sustained at each fastening point.

Additionally the element 6 enhances the strength of the fastening system as each fastener assembly braces the sheets against lateral movement when loads are applied normal to the plane of the sheet 1.

S:P25097D/493/14.11.97 12 Accordingly, the invention may provide a fastening system which displays greater rigidity than traditional systems and may provide for the formation of fastenings which are extremely rigid both longitudinally and laterally while allowing very quick assembly.

Other advantages of the preferred embodiment of the invention include the aesthetic appearance of the upperside of the elements, which is particularly desirable when the elements are used as roof assemblies which is contributed to by the integrity of the protective coating outside the assembly thereby minimising problems of leakage and los* corrosion.

When the shank of the fastener is interpositioned within the aperture and the opening of the sheet and homed s: down, the head bears upon the upperside of the element, thereby a compression force is applied on the body by the head of the fastener. In this manner the head applies a compressive hold down force directly to the element and the sheet even when a washer is provided within the head recess.

The foregoing detailed description is indicative of one embodiment of the invention. Various modifications and improvements obvious to those skilled in the art may be made without departing from the spirit and scope of the invention. For example, the adhesive means may be in the form of a double sided strip of material having peelable type adhesive material with one face retainingly secured by the adhesive to the underside of the element and the other and opposite face provided with and releasably secured to a sheet member in readiness to be peeled free of the strip in readiness for attachment to the cladding sheet by the adhesive material for assembly therewith.

In preferred embodiments the diameter of the aperture is at least equal to but generally greater than the diameter of the shank and less than the width of the head of the fastener. However, in some embodiments the diameter may be less than that of the shank to provide for a tight fit S:P25097D/493/14.11.97 13therebetween.

Further, the illustrated fastener is a screw fastener, however, the invention is not limited to that specific type of fastener and may for example be an impact drivable fastener or other fastener having a shank and a bulbous head.

Further also, the element may be provided with an upstanding annular rib concentric with and encircling the aperture instead of the boss of the preferred embodiment, to provide a substantially flat upper portion against which the skirt may make metal to metal contact. The annular rib may be spaced from the edge of the aperture by a sufficient distance to provide a recess into which at least a portion of the washer may be ensconced.

Additionally, the washer may be an annulus of •rectangular or other cross-section.

Additionally further, the element may be formed from a o "pressed metal disc so that its length matches its width and its edges are more rounded than that of the illustrated embodiment. Indeed in some embodiments the length may be less than the width.

In the claims which follow and in the preceding summary of the invention, except where the context requires otherwise due to express language or necessary implication, 25 the word "comprising" is used in the sense of "including, ie. the features specified may be associated with further features in various embodiments of the invention.

S:P25097D/493/14.11.97

Claims (14)

1. A cladding mounting element for use in fastening a cladding sheet to a support member, said element having a body with at least an upperside and at least an underside, said body being provided with at least one fastener clearance aperture extending from said upperside to said underside wherein at least a portion of said underside is adapted to make contact with the cladding sheet and at least a portion of said portion is provided with adhesive means.

2. A cladding mounting element according to claim 1 wherein the adhesive means is of sufficient tackiness to enable the element to be at least temporarily releasably affixable to the sheet. oeoee:

3. A cladding mounting element according to claim 1 or eeo S.claim 2 wherein said at least a portion of the underside conforms to or complies with the shape and configuration of the surface of the cladding sheet with which it is adapted to -:make contact. eeoc

4. A cladding mounting element according to any one of the preceding claims wherein the element is in the form of a 25 saddle adapted in use to straddle an upstanding rib of the sheet with the fastener clearance aperture in register with a S. crest of said rib. A cladding mounting element according to any one of the preceding claims wherein the underside of the element is shaped to fit neatly over a crest and edge margins of the crest of an upstanding rib of the sheet with the fastener clearance aperture in register with a crest of said rib.

S:P25097D/493/14 .11.97 15

6. A cladding mounting element according to any one of the preceding claims wherein the upperside of the element is provided with a boss having a generally planar or flat upper portion.

7. A cladding mounting element according to any one of the preceding claims wherein at least a portion of the underside defining an edge margin of the underside encircling the fastener clearance aperture is provided with said adhesive means.

8. A cladding mounting element according to any one of the preceding claims wherein a portion of the underside defining a band encircling the fastener clearance aperture disposed away from the aperture may be provided with said adhesive means.

S"9. A method of attaching a sheet of cladding to a support member comprising the steps of: providing a fastener having a head and a shank with a tip; b) providing a cladding sheet mounting element according to any one of the preceding claims; emplacing the cladding sheet mounting element at a 25 requisite disposition on the cladding sheet so that it is at least temporarily releasably affixed thereto by the adhesive means; d) then emplacing the tip within the fastener clearance aperture; and driving the fastener so as to drive the tip and shank through the aperture and into the sheet thereby piercing the sheet, through the sheet and into a support member until the fastener is homed down.

10. A method according to claim 9 comprising the further step of providing a sealing washer on the shank of S: P25097D/493/14.11.97 16 the fastener prior to step

11. A method according to claim 9 or claim wherein the fastener is homed down so that the head bears against the upperside of the element.

12. A method according to any one of claims 9 to 11 wherein the head of the fastener is provided with an annular recess to accommodate at least in part the sealing washer

13. A method according to claim 12 wherein said recess is defined by the shank of the fastener and a skirt depending downwardly from and integral with the head of the fastener.

14. A method substantially as hereinbefore described with reference to one or more of the accompanying drawings. A cladding mounting element substantially as hereinbefore described with reference to one or more of the accompanying drawings. Dated this 14th day of November 1997 25 BHP Steel (JLA) Pty Ltd By their Patent Attorneys GRIFFITH HACK S:P25097D/493/14.11.97