GB2473774A

GB2473774A - Hammer-in fixing

Info

Publication number: GB2473774A
Application number: GB1021616A
Authority: GB
Inventors: James Kenneth Mcalpine
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-03-29
Filing date: 2007-03-29
Publication date: 2011-03-23
Anticipated expiration: 2027-03-29
Also published as: GB2436727A; GB201021616D0; GB0706147D0; GB2473774B; GB0606216D0; GB2436727B

Abstract

A hammer-in fixing 10 for securing composite insulation panels 30 to a rafter 32 or a joist comprises a helical shank 12 having a longitudinal axis and a head 20 defining at least one planar surface 22. The planar surface is fixed adjacent an end of the shank such that the planar surface lies in a plane perpendicular to the longitudinal axis. The cross sectional area of the planar surface is at least 20 times that of the helical shank and the maximum width of the shank is 8mm. A method of manufacturing a hammer-in fixing comprises: providing a head and shank as defined above, in which the head has a profiled portion adapted to receive an end of the shank; engaging the end of the shank with the profiled portion such that the planar surface lies in a plane perpendicular to the longitudinal axis; and securing the head to the helical shank.

Description

Improved Fixing

FIELD OF THE ThWENTION

The present invention relates to fixings, particularly to hamrnerin fixings for S securing composite insulation panels to rafters or joists.

BACKGROUND TO THE INVENTION

Environmental concerns have raised the profile of energy consumption in recent years. These conceais have led to new building regulations Which stipulate insifiation levels which require increased thicknesses of insulation must be used by builders when building houses. Particularly, recent regulations have led to the thickness of the insulation foam used to insulate roofs increasing initially to 90mm from 50mm, and subsequent regulation changes will require the use of panels with learn layers of around 11 Dram to meet the insulation requirements.

insulation can be supplied in composite panels comprising the desired thickness of polyurethane insulation foam fixed to sheets of plywood. To install a composite panel comprising 50mm thick insulation to, for example, a rafter, conventional fixings such as clout nails are hammered through the plywood and then the insulation into engagement with the rafter.

However, clout nails have not proved suitable for securing composite panels comprising 90mm thick insulation, which are necessary to comply with the current regulations. In many cases, these panels are being secured using long screws. Using a screw has significant drawbacks over using a nail; particularly, two operations are required to fix a composite panel with a screw firstly a hole needs to be drilled and 2S then the screw needs to be set, Furthermore, over tightening a screw can compress the insulation, possibly to an extent that the thickness of the insulation is reduced to a nomcompliant thickness, and once set the head of a screw can sit proud of the panel and damage a subsequently applied roof covering.

Additionally, to secure an insulation panel with a foam layer 110mm thick requires a screw of around 150mm long with a 7mm thick shank. A screw of these dimensions has a crosssectional area in excess of 20mm2, leading to the possibility of thermal bridging. Thermal bridging is a process by which heat can cross an otherwise insulated barrier by conduction through a conductive element, such as a screw, passing through the barrier. [fan insulation panel can be thermally bridged by use of 1 0 a thick screw, the insulation effect of the panel may be reduced, possibly leading to noncompliance with the building regulations.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a hammer4n fixing for securing composite insulation panels to a rafter or a joist, the fixing comprising: a helical shank having a longitudinal axis; and a head defining at least one planar surface, the planar surface being fixed adjacent an end of the shank such that the planar surface lies in a plane perpendicular to the longitudinal axis, wherein the cross sectional area of the planar surface is at least 20 tinies that of the helical shank and the maximum width of the helical shank is 8mm.

Hammerin fixings in accordance with an embodiment of the present invention can be used to secure composite insulation panels to a rafter or ajoist in a single 2.5 operation, that is, the fixings can be hammered through the composite panel into a rafter or a joist The helical shank is adapted to, in use, grip the rafter or joist, and the head is sized to maximise contact with the plywood layer of the composite panel to secure the panel to the rafter or joist. This feature is most usduii when the composite panel is to be suspended from a rafter or joist as the head prevents the panel from slipping off the shank, particularly where the thickness of the plywood is less than a flu turn of the helix; the thickness normally required to secure a helical fixing to a inateri at, Preferably, the fixing is self tapping. A self tapping fixing will tend to pass through a composite panel with lithe or no compression of the insulation, Preferably, the head is relatively thin.

Preferably, the head is no more than 1mm thick, Preferably, the head comprises a disc.

Most preferably, the disc is circular, A thin disc of material, that is having two parallel planar surfaces, in use, lies flush against the panel once set. A circular disc minirnises the possibility of a covering, applied over the fixing, snagging on the edge of the head.

Most preferably, the disc is 0.75mm thick, PreferaMy, the head includes a profiled portion adapted to receive the end of the helical shank.

Preferably, the profiled portion is an aperture defined by the head.

Alternatively, the profiled portion is a recess defined by the head.

Preferably, the profiled portion is a complementary shape to the crosssection of the helical shank. Such an arrangement ensures a snug fit between the head and the shank.

Preferably, the helical shank defines a double helix, Preferably, the maximum crosssectional area of the helical shank is less than 15mm2.

Most preferably, the maximum crosssectional area of the shank is approximately 13.5mm2, A small crosssectional area is desirable as it reduces the stress which is applied irk use to the medium through which the fixing is hammered. A small shank crosssectional area also reduces the possibility of thermal bridging of an insulation panel via the fixing making the secured panel noncomp1iant with the building regulations.

Preferably, the crosssectional area of the planar surface of the head is greater 1.0 than 300mm2.

Most preferably, the crosssectional area of the planar surface of the head is 314.2mm2. A crosssectional area of314.2mm equates a planar surface diameter of 20mm.

Preferably, one turn of the helix is greater than 20mm in length along the longitudinal axis.

Preferably, one turn of the helix is 21 mm.

Preferably, the length of the helical shank is at least 130mm, Most preferably, the length of the helical shank is in the range 135mm to 250mm.

Preferably. the fixing comprises metal.

Most preferably, the fixing comprises carbon steel.

Alternatively, the fixing comprises zinc, yellow passivated steel or stainless steel.

Preferably, the fixing is manufactured from two parts.

Most preferably, the two pans are the head and the shank.

Preferably, the head and the shank are fixed together by welding.

Preferably, the head planar surface comprises engagement means for engaging an insulation panel.

Preferably, the head planar surface defines the engagement means.

Preferably, the engagement means extend from the planar surface.

Preferably, the engagement means extend less than 4mm from the planar surface.

Most preferably, the engagement means extend 3.75mm from the planar surface.

1.0 Preferably, the engagement means comprises at least one tang.

Preferably, the at least one tang extends from the planar surface in a direction substantially parallel to the helical shank axis Extending the tang(s) parallel to the shank ensures maximum penetration of the tang(s).

Alternatively, the at least one tang extends in a direction substantially tangential to the direction of rotation, in use, of the hammer fixing. In one embodiment, as the hammer-in fixing is hammered into the surface, the tang or tangs are affanged to dig into the surface of a composite insulation panel in the direction of rotation. Such an arrangemeM provides resistance to the fixing being pulled out by an axial pull.

Preferably, there are a plurality of tangs, Preferably, where the head is a disc, the tangs are pressed out of the disc.

Alternatively, the engagement means comprises a roughened head planar surface.

According to a second aspect of the present invention there is provided a method of manufacturing a hammer fixing, the method comprising: providing a fixing head defining at least one planar surface and a helical shank having a longitudinal axis and a maximum width of 8mm, the cross sectional area of the planar surface being at least 20 times that of the helical shank, the fixing head having a profiled portion adapted to receive an end of the helical shank; engaging the end of the helical shank with the profiled head portion such that one of said planar surfaces lies in a plane substantially perpendicular to the longitudinal axis; and securing the head to the helical shank, Preferably, the method comprises an initial step of pressing a fixing head from a sheet of material.

Preferably. the step of pressing the fixing head loin a sheet of material comprises the pressing an at least one engagement means from the fixing head.

Preferably. the step of securing the head to the helical shank comprises welding or otherwise adhering the head to the helical shank.

The advantages and features of the first aspect of the present invention may he common to the second and third aspects and for the purposes of brevity and clarity these have not been repeated here.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described with reference to the accompanying Figures in which: Figure 1 is a perspective view of a hammer fixing in accordance with a first embodiment of the present invention; Figure 2 is a schematic view of the first side of the head of the hammer fixing ofFigurel; Figure 3 is a schematic view of the hammer fixing of Figure 1 securing a composite insulation panel to a rafter; Figure 4 is a perspective view of an alternative head according to a second embodiment of the present invention; and Figure 5 is a perspective view of an alternative head according to a third embodiment of the present invention

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to Figure 1 there is shown a hamrner4n fixing, generally indicated by reference numeral I 0, according to a first embodiment of the present invention, The fixing 10 comprises a heUcal shank 12 having a longitudinal axis 14.

The helical shank 12 defines a sharpened tip 15, a first helix 16 and a second helix 18, and has a maximum crosssectionai area of 13.5mm2, The fixing 10 further comprises a head 20. The head 20 is a 20mm diameter 1 5 circular disc having a first side 22 and a second side 24. The first and second sides 22,24 are planar and lie in paral1e planes. The crosssectional area of the first head side 22 is 3142mm2, Therefore the crosssectional area of the first head side 22 is more than 23 times the crosssectional area of the helical shank 12.

The helical shank 12 is made by firstly partially flattening a kngth of wire material by a rolling action. The flattened wire is then cut to the required shank length and twisted to form the helixes 16,18. The tip 15 is formed by grinding.

The head 20 is pressed out of a sheet of metal to the required size. Referring to Figure 2 a schematic view of the first side 22 of the head 20 of the hammer fixing a of Figure 1, the head 20 defines an aperture 28 corresponding to the crosssection of the helical shank 12, The aperture 28 is pressed out of the middle of the head 12.

To assemble the fixing 10, the head 20 is pushed onto the first end 26 of the shank 2, such that the shank first end 26 fits into the aperture 28, and a weld is applied to the interface between the head first side 22 and the shank 12.

Figure 3 is a schematic view of the hammer fixing 10 of Figure 1 securing a composite insulation panel 30 to a flat roof rafter 32. The composite insulation panel comprises a 9Omm thick layer of polyurethane foam 34 attached to a 6mm thick sheet of plywood 36.

To secure the composite panel 30, the fixing 36 is hammered through the plywood sheet 36 and the insulation foam 34 into the rafter 32. The fixing 10 is selfi tapping and as it is hammered through the composite panel 30 and the rafter 32. it rotates. The fixing 10 penetrates the rafter 32 to a depth of 35mm, The helical shank 12 will be secured and retained by dense material, such as wood, if the material is thick enough to receive more than one complete turn of the each helix 16)18 and if the shank 12 has penetrated the material to a depth greater than one complete turn of each helix 16,18. The portion of the helical shank 12 indicated by the letter "A" on Figure 2 represents one turn of each helix 16,18. As can he seen from Figure 2, the helical shank 12 has penetrated the rafter 32 to a depth of approximately 1.25 turns of each helix 16,18; sufficient to grip the helical shank 12.

However, the plywood sheet 36 is not thick enough to receive one complete turn of each helix 16,18, and the helical shank 12 is not secured by less dense materials such as the foam layer 34 because the foam layer 34 is not stiff enough to secure and retain the helixes l6,l8.

The plywood sheet 36, and hence the composite panel 30, is therefore restrained by the fixing head 20. The large surface area of the first head side 22 engages the plywood sheet top surtdce 38 securing the composite panel 30 to the rafter 32. The fixing head 22 prevents the composite panel lifting off the rafter 32, for example, in high winds.

The thin disc head 20 lies substantially flush with the plywood sheet top surface 38, pennitting a roof covering (not shown) to he applied over the composite panel 30 without the risk of the fixing 10 snagging and tearing the covering.

Figure 4 is a perspective view of an alternative head 120 according to a second i0 embodiment of the present invention. The alternative head 120 comprises three tangs which extend from the first side 122 of the head 120, The head 120 is pressed out of sheet metal by a stamp which forms the tangs 150 as part of the same manufacturing process.

To assemble the fixing, the shank (not shown) is inserted into the receiving aperture 128 and welded to the head first side 122.

The tangs 150 provide a hammer fixing including the head 120 with additional grip when used to secure a composite panel to a rafter as the tangs 150 penetrate and grip the plywood top sheet.

Figure 5 is a perspective view of an alternative head 220 according to a third embodiment of the present invention. The head 220 is the same as the head 120 of the second embodiment other than the head 220 of the third embodiment does not include the shank receiving aperture 28,128 of the first and second embodiments. In this embodiment the shank (not shown) is welded directly to the surface of the head first side 222.

Various modifications or improvements may be made to the above described embodiment without departing from the scope of the present invention, For exampk, in an alternative embodiment, the composite insulation panel is attached to the underside of a rafter or joist. In this embodiment the fixing head prevents the composite panel from falling away from the rafter or joist. Additionail; in a thrther embodiment a head for the hammer fixing could he provided with the shankreceiving aperture 28 being a blind bore or recess rather than a throughbore.

It will be appreciated the principal advantage of the above described embodiments is that a composite insulation panel can be secured to a rafter or joist in one operation. It will also be appreciated that the invention may have application in securing other tbrms of pane! to other members, for example in securing foil covered insulating foam to vertical studs,

Claims

A hammer-in fixing for securing composite insulation panels to a rafter or a joist, the fixing comprising: a helical shank having a longitudinal axis; and S a head defining at least one planar surface, the panar surface being fixed adjacent an end of the shank such that the planar surface lies in a plane perpendicular to the longitudinal axis, wherein the cross sectional area of the planar surface is at least 20 times that of the helical shank and the maximum width of the helical shank is 8mm,
2 The hammer-in fixing of claim 1, wherein the fixing is self tapping.
3 The hammer-in fixing of any preceding claim, wherein the head is no more than 1mm thick.
4. The hammer4n fixing of any preceding claim, wherein the head comprises a disc.

The hammer-in fixing of any preceding ciairn wherein the head includes a profiled portion adapted to receive the end of the helical shank.

6 The hammer-in fixing of claim 5, wherein the profiled portion is an aperture defined by the head.

7 The hammer-in fixing of chum 5, wherein the profiled portion is a recess defined by the head.

8 The hammer-in fixing of any of claims 5 to 7, wherein the profiled portion is a S complementary shape to the crosssection of the helical shank.

9 The hamsnerin fixing of any preceding claim, wherein the helical shank defines a double helix.

10 The hammerin fixing of any preceding claim, wherein the crosssectiona1 area of the helical shank is less than 15mm2, 11 The hamnuerin fixing of any preceding claim, wherein the crosssectional area of the shank is approximately 13.5mm2.12 The harnmerin fixing of any preceding claim, wherein the crosssectional area of the planar surface of the head is greater than 300mm2, 13 The hammer-in fixing of any preceding claim, wherein the crosssectional area of the planar surface of the head is 314.2mm2, 14 The hammerin fixing of any preceding claim, wherein one turn of the helix is greater than 20mm in length.The hannrier4n fixing of any preceding claim, wherein one turn of the helix is 21mm.16 The hamnier4n fixing of any preceding claim, wherein the length of the S helical shank is at least 130mm.17 The hammer4n fixing of any preceding claim, wherein the length of the helical shank is in the range 135mm to 250mm.1 8 The hammerin fixing of any preceding claim, wherein the fixing comprises rneta 19 The hammer-in fixing of any preceding claim, wherein the fixing comprises carbon steel.The hamnier4n fixing of claim 1 9, wherein the fixing comprises zinc yellow passivated steel or stainless steel.21 The hammer4n fixing of any preceding claim, wherein the fixing is manufactured from two parts.22 The harnmer4n fixing of claim 21. wherein the two parts are the head and the shank 23 The hammer-in fixing of claim 22, wherein the head and the shank are fixed together by welding.24 [he hammer-in fixing of any preceding claim, wherein the at least one head planar surface comprises engagement means for engaging an insulation panel, The hammer-in fixing of claim 24, wherein the at least one head planar surface defines the engagement means.26 The hammer-in fixing of either of claims 24 or 25 wherein the engagement means extend from the at least one head planar surface.27 The hammer-in fixing of claim 26, wherein the engagement means extend!ess than 4mm from the at least one head planar surface.28 The hammer-in fixing of either of claims 26 or 27. wherein at ieast part of the engagement means extend 3.75mm from the at ieast one head planar surface.29 The hammer-in fixing of any of claims 24 to 28, wherein the engagement means comprises at least one tang.The hammer-in fixing of claim 29, wherein the at least one tang extends from the at east one head panar surface in a direction substantially paraflel to the helical shank axis.31 The hammer-in fixing of claim 30, wherein the at least one tang extends in a direction substantially tangential to the direction of rotation.32 The hammer-in fixing of any of claims 29 to 31, wherein there are a plurality S of tangs.33 The hammer-in fixing of any of claims 29 to 32, then dependent on claim 4, wherein where the head is a disc, the at least one tang is pressed out of the disc.34 The hammer-in fixing of any of claims 24 to 33, wherein the engagement means comprises a roughened head planar surface.A method of manufacturing a hammer-in fixing, the method comprising: providing a fixing head defining at least one planar surface and a helical shank having a longitudinal axis and a maximum width of 8mm, the cross sectional area of the planar surface being at least 20 times that of the helical shank, the fixing head having a profiled portion adapted to receive an end of the helical shank; engaging the end of the helical shank with the profiled head portion such that one of said planar surfaces lies in a plane substantially perpendicular to the longitudinal axis; and securing the head to thc helical shank.36 The method of claim 35, further comprising an initial step of pressing a fixing head from a sheet of material. flrJ37 The method of 36, wherein the step of pressing the fixing head from a sheet of material comprises the pressing an at least one engagement means from the fixing head.s 38 The method of any of claims 35 to 37. wherein the step of securing the head to the helical shank comprises welding the head to the helical shank.