NZ738588A - A structual member and method of manufacture - Google Patents
A structual member and method of manufactureInfo
- Publication number
- NZ738588A NZ738588A NZ738588A NZ73858816A NZ738588A NZ 738588 A NZ738588 A NZ 738588A NZ 738588 A NZ738588 A NZ 738588A NZ 73858816 A NZ73858816 A NZ 73858816A NZ 738588 A NZ738588 A NZ 738588A
- Authority
- NZ
- New Zealand
- Prior art keywords
- return
- structural member
- side edge
- sheet
- rst
- Prior art date
Links
- 238000004519 manufacturing process Methods 0.000 title description 14
- 239000000463 material Substances 0.000 claims abstract description 30
- 229910000831 Steel Inorganic materials 0.000 claims description 20
- 239000010959 steel Substances 0.000 claims description 20
- 210000001847 Jaw Anatomy 0.000 claims description 13
- 238000007373 indentation Methods 0.000 description 13
- 238000002788 crimping Methods 0.000 description 11
- 230000015572 biosynthetic process Effects 0.000 description 8
- 238000005755 formation reaction Methods 0.000 description 8
- 238000000034 method Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 4
- 238000006011 modification reaction Methods 0.000 description 4
- 210000001503 Joints Anatomy 0.000 description 3
- 238000005452 bending Methods 0.000 description 3
- 238000005097 cold rolling Methods 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 239000000789 fastener Substances 0.000 description 2
- 238000005246 galvanizing Methods 0.000 description 2
- 238000005304 joining Methods 0.000 description 2
- 238000004826 seaming Methods 0.000 description 2
- 241000271566 Aves Species 0.000 description 1
- 241000269799 Perca fluviatilis Species 0.000 description 1
- 241000269800 Percidae Species 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 230000000875 corresponding Effects 0.000 description 1
- 231100000078 corrosive Toxicity 0.000 description 1
- 231100001010 corrosive Toxicity 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000001419 dependent Effects 0.000 description 1
- 230000000994 depressed Effects 0.000 description 1
- 230000003467 diminishing Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
Abstract
structural member having an enclosed pro?le is formed from a sheet of material having a longitudinal axis between a front edge and a rear edge, and a transverse axis across the longitudinal axis between a ?rst side edge and a second side edge. The structural member includes a ?rst ?ange having a ?rst side and a second side, a ?rst web extending from the ?rst side of the ?rst ?ange towards the ?rst side edge, a second web extending from the second side of the ?rst ?ange towards the second side edge, and a second ?ange. The second ?ange includes a ?rst return between the ?rst web and the ?rst side edge, the ?rst return further including an outwardly facing hook between the ?rst return and the ?rst side edge. The second ?ange also includes a second return between the second web and the second side edge, the second return further including an inwardly facing hook between the second return and the second side edge. The outwardly facing hook and the inwardly facing hook project into each other to provide an overlapping section, and the second ?ange includes at least one crimp in the overlapping section, where a width of the crimp in the direction of the transverse axis of the sheet is less than that of the overlapping section.
Description
JAWs ref: 303709/73
A STRUCTUAL MEMBER AND METHOD OF MANUFACTURE
STATEMENT OF CORRESPONDING APPLICATIONS
This application is based the provisional specification filed in relation to New Zealand Patent Application
No. 727847, the entire contents of which are incorporated herein by reference.
TECHNICAL FIELD
The present disclosure relates to a structural member, more particular a hollow structural section cold-
rolled from a sheet of material.
BACKGROUND
Cold-formed structural members are known for use in construction, for example as purlins, rafters,
girts, and the like. Cold-forming refers to the shaping of flat steel sheet without the use of applied heat.
Light gauge steel in particular when cold-formed typically provides considerably more strength for its
weight than hot-formed steel (i.e. processed above its recrystallisation temperature).
The roll-forming process is the method generally preferred for volume production of cold-formed
structural members, and is often termed cold-rolling. In this process the steel sheet is passed through a
series of rollers which incrementally ‘roll’ the shape from the flat sheet.
Known roll-formed light-gauge steel structural members are typically open shapes. C and Z shaped
purlins are the most common, although other shapes and variations on these shapes may be found.
Such open shapes are easier to manufacture than enclosed shapes. However, enclosed shapes such as
rectangles, squares, and other hollow shapes are more stable and less prone to buckling and distortion
when subjected to load than open shapes. Further, open shapes such as in the case of C and Z shaped
purlins are also notorious for providing bird roosting perches when used on the underside of roofing.
This can be a serious nuisance due to the accumulation of bird excrement both on the beams where it is
very corrosive, and beneath the beams where it can also pose serious problems.
A method that has been employed is the use of continuous welding to join the edges of a single sheet of
steel together after roll-forming, to form a hollow section. However, in order to provide protection
against corrosion of the structural member it is desirable to galvanise the light gauge steel. Welding
JAWs ref: 303709/73
precludes galvanising of the sheet prior to cold-rolling, which is much more economical and convenient
than finishing or galvanising the structural member after cold-forming.
Another method that has been employed is the use of one of a variety of lock-seam methods to join the
edges of a single sheet of steel together after roll-forming, to form a hollow section. Lock-seaming folds
the edges of the sheet over each other to produce a mechanical joint. However, these methods require
the production of very tight radii to achieve the fold, and are difficult to apply to steel sheet other than
very thin thicknesses, typically 1.0mm or less. Furthermore, it is particularly difficult to design a single
roll-forming machine that will perform lock-seaming for a range of sheet thicknesses which may be
required to form a structural member, for example between 1.0 mm to 3.0 mm – which would
otherwise necessitate investment in additional capital equipment.
It is an object of the present invention to address at least one of the foregoing problems or at least to
provide the public with a useful choice.
All references, including any patents or patent applications cited in this specification are hereby
incorporated by reference. No admission is made that any reference constitutes prior art. The
discussion of the references states what their authors assert, and the applicants reserve the right to
challenge the accuracy and pertinency of the cited documents. It will be clearly understood that,
although a number of prior art publications are referred to herein, this reference does not constitute an
admission that any of these documents form part of the common general knowledge in the art, in New
Zealand or in any other country.
Unless the context clearly requires otherwise, throughout the description and the claims, the words
“comprise”, “comprising”, and the like, are to be construed in an inclusive sense as opposed to an
exclusive or exhaustive sense, that is to say, in the sense of “including, but not limited to”.
Further aspects and advantages of the present invention will become apparent from the ensuing
description which is given by way of example only.
SUMMARY
According to one aspect of the present disclosure there is provided a structural member having an
enclosed profile formed from a sheet of material having a longitudinal axis between a front edge and a
rear edge, and a transverse axis across the longitudinal axis between a first side edge and a second side
edge, the structural member including:
a first flange having a first side and a second side;
JAWs ref: 303709/73
a first web extending from the first side of the first flange towards the first side edge;
a second web extending from the second side of the first flange towards the second side edge;
a second flange including:
a first return between the first web and the first side edge, the first return further
including an outwardly facing hook between the first return and the first side edge;
a second return between the second web and the second side edge, the second return
further including an inwardly facing hook between the second return and the second side edge,
wherein the outwardly facing hook and the inwardly facing hook project into each other
to provide an overlapping section, and
wherein the second flange includes at least one crimp in the overlapping section, and
the width of the crimp in the direction of the transverse axis of the sheet is less than that of the
overlapping section.
According to another aspect of the present invention there is provided a method of manufacturing a
structural member substantially as described herein from a sheet of material having a longitudinal axis
between a front edge and a rear edge, and a transverse axis across the longitudinal axis between a first
side edge and a second side edge, wherein the method includes the steps of:
roll-forming the sheet of material to form the first return and the second return;
roll-forming the sheet of material to form the first flange, the first web, and the second web;
directing the first return towards the second return and forcing the first return away from the
first flange and/or forcing the second return towards the first flange such that the first return and
second return pass each other to overlap;
releasing the first return and/or second return, such that the outwardly facing hook and the
inwardly facing hook project into each other to provide the overlapping section; and
crimping the overlapping section, wherein the width of the crimp in the direction of the
transverse axis of the sheet is less than that of the overlapping section.
In an exemplary embodiment, the structural member may be formed from a single sheet of material.
However, it is also envisaged that in exemplary embodiments the structural member may be formed
from two sections, such that the first flange is also configured in the manner described with respect to
JAWs ref: 303709/73
the second flange (i.e. having overlapping hooks crimped in the manner described).
According to one aspect of the present disclosure there is provided a method of joining two edges of a
sheet of material, wherein the method includes:
forming a first hook on one edge, and a second hook on the second edge,
positioning the first and second hooks such that they project into each other to provide an
overlapping section, and
crimping the overlapping section, wherein the width of the crimp in the direction of the
transverse axis of the sheet is less than that of the overlapping section.
In an exemplary embodiment, the structural member is an elongate beam. The length of the beam may
be that of the sheet of material from which it is formed, or cut to length.
Reference to the structural member having an enclosed profile should be understood to mean that the
cross-sectional shape of the member is hollow, with the interior surfaces of the flanges and webs
enclosing an interior space of the member – i.e. a hollow structural section. In addition to providing a
structurally efficient shape, such a profile is envisaged as avoiding creating ledges for birds to perch on –
particularly when used in the construction of roofs. It should be appreciated that reference to an
enclosed profile is not intended to exclude the production of apertures in the structural member (for
example, for the insertion of fasteners to secure fittings to the structural member).
Where the structural member is used in roof structures, it is envisaged that a flange may be a horizontal
element of the structural member, predominantly resisting most of the bending moment experienced
by the structural member in use. Similarly, in such an orientation a web of the structural member may
be a vertical element of the structural member, predominantly resisting most of the shear forces
experienced by the structural member in use. It should be appreciated that this is not intended to be
limiting, as use cases are envisaged in which the structural member may be oriented such that the
flanges are vertical elements – for example where used as a girt in a wall structure to resist wind loads.
Reference to a return should be understood to mean portion of the sheet of material bent out of
alignment with the adjacent section, typically inwardly. In an exemplary embodiment, the returns may
be substantially 90° returns. However, it should be appreciated that this is not intended to be limiting;
for example, the angle of the returns may be such that they are biased to clamp against the adjacent
portion of the structural member.
In an exemplary embodiment, the first web and/or the second web may be formed such that they are
biased towards an angle of greater than 90° relative to the first flange. It is envisaged that this
JAWs ref: 303709/73
outwardly acting bias may assist in maintaining the shape of the structural member.
In an exemplary embodiment, the sheet of material may be made of steel. In an exemplary
embodiment, the sheet of material is light gauge steel, more particularly steel having a thickness
between about 0.3 mm and about 3.0 mm. In an exemplary embodiment, the light gauge steel may
have a thickness between about 0.6 mm and about 2.5 mm. In an exemplary embodiment, the light
gauge steel may have a thickness between about 0.75 mm and about 2.25 mm. The form of the
structural member is such that tight folds are not required, which allows the same roll-forming
equipment to be used for a range of thicknesses of sheet. It should be appreciated that this is not
intended to be limiting, and that the sheet of material may be made of another metal or ductile
material suitable for cold roll-forming.
In an exemplary embodiment, the sheet of material may be treated for corrosion protection prior to
forming the structural member. For example, the sheet of material may be galvanised. The form of the
structural beam allows for an enclosed profile to be produced without the use of welding or other heat
based joining techniques, which could otherwise compromise corrosion protection applied prior to
formation of the member.
Reference to crimping should be understood to mean the act of localised deformation of two or more
layers of sheet material to produce a friction joint between them. It should be appreciated that
reference to a “crimp” may therefore be understood to mean the localised deformation resulting from
this action. In an exemplary embodiment, the crimping may be performed by applying the deforming
force with a tool on one side of the overlapping section, with the other side of the overlapping section
bearing against an anvil.
In an exemplary embodiment, crimping may be performed on opposing sides of the overlapping section
– i.e. the flange having the overlapping section may include a first crimp on a first side of the
overlapping section, and a second crimp on a second side of the overlapping section.
As a point of reference for explanation, each hook may include a lead-in portion, a return bend, and
return portion ending at the side edge of the sheet of material. In an exemplary embodiment, at least
one of the hooks may include a recurved section in the lead-in portion. This recurved section may allow
the outward facing surfaces of the respective lead-in portions to be substantially level.
In an exemplary embodiment, the return bend of the hooks may be such that the return portion is open
beyond parallel relative to the lead-in portion – i.e. more open that a “U” shape. It is envisaged that this
may be particularly applicable to embodiments in which the structural member is manufactured from a
single sheet, allowing for the overlap to be achieved by a lateral motion with a relatively small degree of
JAWs ref: 303709/73
deflection of the returns as they pass each other. However, it should be appreciated that this is not
intended to be limiting to all embodiments.
Further, it should be appreciated that in exemplary embodiments in which the structural member is
formed from two sections the sections may be positioned relative to each other through a sliding
motion along the longitudinal axis. In such a configuration, the hooks may be generally “U” shaped or
closed beyond parallel.
For ease of understanding, the joint created by the crimped hooks will be described as if the crimping
force is applied from the outside of the structural member – i.e. is applied inwardly. However, it should
be appreciated that this is not intended to be limiting to all embodiments, and in exemplary
embodiments the crimping force may be applied from inside the structural member.
In an exemplary embodiment, the width of the crimp along the transverse axis of the sheet may be
about, or less than, the distance between the respective return bends of the hooks through the overlap.
In doing so, formation of the joint does not rely on flattening of the return bends – which for thicker
sheets of material would likely require a bend radius below a recommended minimum bend radius.
Determination of the minimum bend radius may consider factors such as sheet material (for example, a
higher tensile steel may require a higher bend radius), sheet thickness, the bending angle (generally a
tighter radius may be used for a more open angle – e.g. a tighter radius may be used for a 90° bend
than a 180° bend), and tolerance for tensile cracking (dependent on the finish and intended
application). Minimum bend radius is typically expressed as a multiple of the thickness (T), e.g. 3T. A
traditional lock seam must use a 0.5T radius to achieve flatness.
In an exemplary embodiment, the minimum bend radius may be greater than 0.5T. In an exemplary
embodiment, the minimum bend radius may be about or greater than 1.0T. In an exemplary
embodiment, the minimum bend radius may be about or greater than 2.0T.
It is envisaged that the joint described herein may enable a single former to be used to manufacture
structural members from different thicknesses of sheet. For example, a former configured to produce a
minimum bend radius of approximately 1.0T from 2.00 mm sheet may also be used to process 1.00 mm
sheet (with a resulting bend radius of approximately 2.0T) – with the design of the joint being such that
this difference in bend radius does not negate the effectiveness of the joint.
In an exemplary embodiment, the crimp in the overlapping section may be substantially centred in the
overlapping section. In an exemplary embodiment including a first crimp on a first side of the
overlapping section, and a second crimp on a second side of the overlapping section, a centre point of
the first crimp may be offset from a centre point of the second crimp along the overlapping section.
JAWs ref: 303709/73
In an exemplary embodiment, the crimp may include an indentation in the hook to which the deforming
force is applied. In an exemplary embodiment, the indentation may be provided in the lead-in portion
of the hook.
In an exemplary embodiment, the depth of the indentation may be sufficient to bear the end of the
return portion of one of the hooks against the return portion of the other hook, without flattening the
returns entirely – i.e. the returns do not bear against each other in their entirety through the overlap.
A further understanding of the functional and advantageous aspects of the present disclosure can be
realised by reference to the following detailed description and drawings.
BRIEF DESCRIPTION OF DRAWINGS
Further aspects of the present disclosure will become apparent from the following description which is
given by way of example only and with reference to the accompanying drawings in which:
is a cross-sectional view of an exemplary structural member according to one aspect of
the present disclosure;
is a cross-sectional view of an exemplary structural member according to one aspect of
the present disclosure;
is a cross-sectional view of an exemplary structural member in a first stage of
manufacture according to one aspect of the present disclosure;
is a cross-sectional view of the exemplary structural member in a second stage of
manufacture;
is a cross-sectional view of the exemplary structural member in a third stage of
manufacture;
is a cross-sectional view of the exemplary structural member in a fourth stage of
manufacture according to one aspect of the present disclosure;
is a cross-sectional view of the exemplary structural member in a fifth stage of
manufacture;
is a cross-sectional view of an exemplary joint for an exemplary structural member in a
first stage of formation according to one aspect of the present disclosure;
is a cross-sectional view of the exemplary joint in a second stage of formation;
JAWs ref: 303709/73
is a cross-sectional view of the exemplary joint in a third stage of formation, and
is a cross-sectional view of the exemplary joint in a fourth stage of formation.
DETAILED DESCRIPTION
illustrates an exemplary structural member in the form of an elongate beam 100. The beam 100
is formed from a single sheet of material, for example light gauge galvanised steel having a thickness of
between about 0.3 mm to 3.0 mm.
The beam 100 includes a first flange 102. A first web 104 extends from a first side of the first flange
102. A first return 106 is formed at an end of the first web 104 distal from the first flange 102,
substantially parallel with the first flange 102. A second web 108 extends from a second side of the first
flange 102, substantially parallel with the first web 104. A second return 110 is formed at an end of the
second web 108 distal from the first flange 102, substantially parallel with the first flange 102.
In the exemplary embodiment illustrated, swages 112-1 to 112-6 are provided in the first flange 102,
first web 104, and the second web 108 for additional strength.
The first return 106 and second 110 are joined to provide a second flange by a joint 300, as shown in
greater detail in and described below.
In an exemplary embodiment, the beam 100 may be installed with the first flange 102 against the
material to which the beam 100 is to be secured. For example, where the beam 100 is used to support
roofing, the beam may be installed with the first flange 102 facing upwardly, and the roofing material
fastened thereto. In doing so, a fastener (such as a screw) is only required to pass through one layer of
the sheet of material from which the beam 100 is formed.
illustrates an exemplary structural member in the form of an elongate beam 150. The beam 150
is formed from two sheets of material, for example light gauge galvanised steel having a thickness of
between about 0.3 mm to 3.0 mm.
The beam 150 includes a first section formed of a web 152-1 having a first return 154-1 at one end, and
a second return 156-1 at the distal end, substantially parallel with the first return 154-1. The beam 150
further includes a second section formed of a web 152-2 having a first return 154-2 at one end, and a
second return 156-2 at the distal end, substantially parallel with the first return 154-2.
The first and second sections of the beam 150 are joined by joints 300-1 and 300-2 to create the box
section illustrated.
JAWs ref: 303709/73
In the exemplary embodiment illustrated, swages 158-1 to 158-4 are provided in the webs 152-1 and
152-2 for additional strength.
It should be appreciated that while beam 100 and beam 150 are illustrated as having the joints 300 in
the ends of the respective beams, it is also envisaged that in exemplary embodiments the joints may be
provided in the sides of those beams (for example, in one of the first web 104 or the second web 104 of
beam 100, or in webs 152-1 and 152-2 of beam 150).
-2E illustrate the manufacture of the beam 100 from a single sheet 200 of light gauge steel using
cold-rolling techniques. The method is illustrated after a first “outward facing” hook 202 has been
formed in a first edge of the sheet 200, and a second “inward facing” hook 204 has been formed in a
second edge of the sheet 200. In a first step, rollers act to bend the sheet 200 about points 202-1 and
202-2 (see ) to produce the first and second returns 106 and 108 (see ).
The upper flange 102 is then formed by bending the sheet about points 208-1 and 208-2 (see ),
with the first web 104 and second web 108 rolled out (see ).
The first and second webs 104 and 108 are rolled closer together. When they begin to meet each other,
as seen in the second return 110 is depressed towards the upper flange 102 so that the first
return 106 can be lifted over it, while at the webs 104 and 108 continue to be pushed closer together.
Referring to , the inward facing hook 204 of the first return 106 overlaps with the outward facing
hook 202 of the second return 110. The joint 300 may then be formed, as will be described with
reference to FIGs. 3A to 3C.
Referring to , the outward facing hook 202 includes a lead-in portion 302-1, a return bend 304-1,
and a return portion 306-1 ending at the side edge of the sheet of material 200. The return portion 306-
1 of the outward facing hook 202 includes a recurved section 308. The inward facing hook 204 includes
a lead-in portion 302-2, a return bend 304-2, and a return portion 306-2 ending at the other side edge
of the sheet of material 200.
It may be seen that in this exemplary embodiment the return portions 306-1 and 306-1 are open
beyond parallel relative to the lead-in portions 302-1 and 302-2. This assists with positioning the hooks
202 and 204 such that they overlap each other in the manner illustrated.
As shown in , an anvil 310 (for example, a roller wheel) is provided on the inward facing surface
of the lead-in portion 302-1 of the outward facing hook 202, and a crimping tool 312 (for example, a
bead on a roller wheel) is brought to bear on the outward facing surface of the lead-in portion 302-2 of
the inward facing hook 204 in a position centred on the overlap of the hooks 202 and 204. The hooks
JAWs ref: 303709/73
202 and 204 are deformed such that the lead-in portion 302-2 of the inward facing hook 204 bears
against the return portion 306-1 of the outward facing hook 202, and the return portion 306-2 of the
inward facing hook 204 bears against the lead-in portion 304-1 of the outward facing hook 202, and the
lead-in portions 302-1 and 302-2 and return portions 304-1 and 304-2 are brought into parallel.
Referring to , the crimping tool 312 (not shown in , but see ) continues to deform
the inward facing hook 204 such that an indentation 314 is formed in the lead-in portion 302-2. The
indentation 314 deflects the return portion 306-1 of the outward facing hook 202 such that its distal
end bears against the return portion 306-2 of the inward facing hook 204, while the end of the return
portion 306-1 of the outward facing hook 202 adjacent the return bend 304-1 remains elevated above
the return portion 306-2 of the inward facing hook 204 with a gap 316 therebetween. The numerous
points of contact between the hooks 202 and 204 may reduce the potential for relative movement,
particularly in circumstances in which the beam is subjected to twisting forces.
Referring to , in an exemplary embodiment a second indentation 318 may be formed in the lead-
in portion 302-1 of the outward facing hook 202. The second indentation 318 deforms the return
portion 306-2 of the inward facing hook 204, and bears it against the return portion 306-1 of the
outward facing hook 202. It is envisaged that this may further increase the tightness and integrity of the
joint 300 in comparison with that illustrated in , without increasing the minimum bend radii
used. However, it should be appreciated that the joint 300 in the stage illustrated in may still
have application for use in the exemplary beams described herein.
In an exemplary embodiment, the second indentation 318 may be formed subsequently to formation of
the indentation 314. In an exemplary embodiment, the second indentation 318 may be formed
simultaneously with formation of the indentation 314 – for example with a second crimping tool
mirroring crimping tool 312.
In an exemplary embodiment, a centre point 320 of the indentation 314 may be offset from a second
centre point 322 of the second indentation 318 along the length of the joint 300. For example, in the
exemplary embodiment illustrated, the centre point 320 may be closer to the free end of the return
portion 306-1 of the outward facing hook 202 than the second centre point 322 is. It is envisaged that
this may assist with reducing the spring back of the return portions 306-1 and 306-2.
The entire disclosures of all applications, patents and publications cited above and below, if any, are
herein incorporated by reference.
JAWs ref: 303709/73
Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement
or any form of suggestion that that prior art forms part of the common general knowledge in the field
of endeavour in any country in the world.
Where in the foregoing description reference has been made to integers or components having known
equivalents thereof, those integers are herein incorporated as if individually set forth.
It should be noted that various changes and modifications to the presently preferred embodiments
described herein will be apparent to those skilled in the art. Such changes and modifications may be
made without departing from the spirit and scope of the invention and without diminishing its
attendant advantages. It is therefore intended that such changes and modifications be included within
the present invention.
The invention may also be said broadly to consist in the parts, elements and features referred to or
indicated in the specification of the application, individually or collectively, in any or all combinations of
two or more of said parts, elements or features.
Aspects of the present invention have been described by way of example only and it should be
appreciated that modifications and additions may be made thereto without departing from the scope
thereof, as defined by the appended claims.
JAWs ref: 303709/73
Claims (6)
1. A structural member having an enclosed profile formed from a sheet of material having a longitudinal axis between a front edge and a rear edge, and a transverse axis across the longitudinal axis between a first side edge and a second side edge, the structural member including: a first flange having a first side and a second side; a first web extending from the first side of the first flange towards the first side edge; a second web extending from the second side of the first flange towards the second side edge; a second flange including: a first return between the first web and the first side edge, the first return further including an outwardly facing hook between the first return and the first side edge; a second return between the second web and the second side edge, the second return further including an inwardly facing hook between the second return and the second side edge, wherein the outwardly facing hook and the inwardly facing hook project into each other to provide an overlapping section, and wherein the second flange includes at least one crimp in the overlapping section, and a width of the crimp in the direction of the transverse axis of the sheet is less than that of the overlapping section.
2. The structural member of claim 1, wherein the structural member is formed from a single sheet of material.
3. The structural member of claim 2 or claim 3, wherein the structural member is an elongate beam.
4. The structural member of any one of claims 1 to 3, wherein at least one of the first web and the second web are biased towards an angle of greater than 90° relative to the first flange.
5. The structural member of any one of claims 1 to 4, wherein the sheet of material is light gauge steel,
6. The structural member of claim 5, wherein the light gauge steel has a thickness between about 0.3 mm and about 3.0 mm. JAWs ref:
Publications (1)
Publication Number | Publication Date |
---|---|
NZ738588A true NZ738588A (en) | 2017-12-22 |
Family
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