Note: Descriptions are shown in the official language in which they were submitted.
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STRUCTURAL COMPONENTS AND THEIR MANUFACTURE
This invention relates to the processing of strip material and its subsequent
assembly into structures/frames and panels. The invention also relates to the
assembly of such panels and structural frames into three-dimensional modules
for the commercial and residential building industries.
Steel is a building material that has a number of advantages over conventional
materials such as bricks, concrete cement and timber. These advantages
include: non-combustible; fully recyclable; very low waste during
construction; dimensionally very accurate; very low maintenance; very high
thermal and acoustic performance. The application of steel has been limited
in that suppliers have not developed manufacturing techniaues which
sufficiently exploit these potential advantages at a competitive price. Steel
is
presently a rather expensive alternative in most situations, particularly the
housing industry, and is mainly found in niche applications where its many
advantages outweigh the initial high costs.
One of steel's major potential advantages is the reduction in lead-time in the
construction of a building as much of the pre-assembly work can be done off
site. Typically, the degree of pre-assembly will vary on the application. This
can range from the supply of internal (non-load bearing) partitions, through
to load bearing panels which are connected together on site and structural
modules. Such modules can be fully fitted out with all necessary decorations
and interior fittings if required and located as a finished unit.
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Such panels and modules are typically fabricated from a plurality of cold-
formed sections which are cut to length and then joined together (e.g. butt-
welding). To ensure that the panels are square and dimensionally accurate,
they are usually assembled on a jig that locates each section prior to fixing.
For three-dimensional modules such jigs are large and complex.
One of the major limitations of such steel framing systems results from the
variability in the design. This leads to high cost of design and expensive
investment in jigs that are tailored to each new design. These overheads
prohibit the use of steel in a number of applications and seriously limit its
potential market.
There is therefore great advantage to be gained from a production method
that can dramatically reduce the amount of assembly hardware required.
A flexible production method is described here that allows the manufacture of
such panels and modules without the use of any complex jigs or locating
tools. The only tools that are required are not specific to any particular
panel
design, thus drastically reducing the investment required in tooling for a
design and eliminating the lead time associated with its manufacture.
Furthermore, it is shown how such panels can be interconnected without jigs
and how complete three-dimensional structures can be assembled with a high
degree of inherent strength.
The key to the simplification lies in the ability of modern section rolling
equipment to punch holes and cut to length sections with tremendous
accuracy and repeatability. Thus it is possible to incorporate in the sections
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themselves, certain geometric information that can be used during the
assembly process. Such information can take the form of such features as the
overall length of a section, the location of a punched hole or the location of
a
notch for an intended fold.
In the preferred embodiment, it is possible to produce a section that needs no
further processing to allow the formation of a panel of predetermined
geometry with only one angular or linear dimension check. (In practice, the
number of external references required equals N minus three, where N is the
number of sides of the polygon that the frame describes. Hence, for a typical
rectangular frame as found in the construction industry, only one reference
dimension is required.)
The invention will now be described, by way of example, with reference to
the accompanying drawings, in which:
Figure 1 is a perspective schematic view of a typical rectangular frame, the
production of which the present invention, in one embodiment, seeks to
simplify,
Figure 2 is a perspective view of a cold-formed metal section of the
invention,
Figure 3 shows the section of Figure 3 being assembled into the form of the
frame of Figure 1,
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Figure 4 is a scrap view of a corner of the frame, together with a reference
tool for checking the angle of the corner,
Figure 5 is a view similar to Figure 4, showing a different reference tool,
Figure 6 is a scrap view of a section of another embodiment of the invention,
Figure 7 is a scrap perspective view of the section of Figure 6 folded to form
a frame,
Figure 8 is a scrap view of a section of a still further embodiment of the
invention,
Figure 9 is a perspective view showing a length of the section of Figure 8 in
the form of a Tipped channel,
Figure 10 is a scrap perspective view of the channel section of Figure 9
folded to form a frame,
Figure 11 is a scrap view of a section of a yet still further embodiment of
the
mvenrion,
Figure 12 is a scrap perspective view of the section of Figure 11 folded to
form a frame,
Figures 13 and 14 correspond to Figures 9 and 10 for another embodiment of
the invention,
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Figure 15 shows frames of the invention joined together to form a larger
composite frame,
Figures 16a and 16b are respective scrap perspective views showing the
means of joining together said frames,
Figure 17 is a perspective view of a modular frame for a building constructed
with frames assembled from sections of the invention,
Figure 18 is an alternative building frame similar to that of Figure 17,
Figures 19 and 20 are respectively perspective views of different forms of
triangular trusses assembled from sections of the invention,
Figures 21 and 22 are respectively perspective views of different shapes of
further frames assembled from sections of the invention, and
Figures 23 and 24 are respectively perspective views of a section of the
invention formed into a core, and a beam formed of said core between outer
sections.
Conventionally, the closed rectangular frame A, shown in Figure 1, would be
constructed using four separate pieces of section that are cut to length
individually. Each section is then inserted into a jig which is adapted to the
particular design of panel to be produced. When located, the sections are
clamped in place so that the ends of the sections can be joined together
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(welded, riveted etc.) The role of the jig is to ensure that: 1) the
individual
sections locate relative to each other to form the correct effective
dimensions
of the frame, and 2) the sections meet at the correct angles.
It is recognised that if the individual sections of precise length can be
accurately positioned relative to each other to form a closed pivoting
rectangular frame, then only one angle needs to be specified in order to form
a frame of the correct geometry. This invention describes a method of
forming such a frame in this manner, thus greatly simplifying the framing
process. This is made possible by the ability of modern section rolling
equipment to punch and cut with tremendous accuracy during the rolling
process. Therefore during rolling the section, it is possible to embed all the
necessary geometric information required to form a frame in the manner
presented.
There are two basic forms of this geometric information. Firstly, it is
necessary to precisely locate consecutive sections relative to each other such
that the linear dimensions of the frame are correct. To bring the ends of two
plain sections together is not precise or robust enough to make frames of the
accuracy required.
Two methods of locating adjacent sections are presented. The first method
involves notching the section such that consecutive sections are joined by a
tab that acts as a hinge corresponding to the apex of the frame. This method
has the advantage that four consecutive segments can be quickly folded into a
parallelogram of known perimeter (thus just needing the right angle at the
open end to be defined to form a rectangular frame). One disadvantage of this
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method is that a large frame results in difficult handling of sections of
length
equal to the perimeter of the frame. A second disadvantage is that if the
notch
gap is wide, the pivot (and therefore the frame) is imprecise. A third
disadvantage is that to close the frame, the open end still needs some means
of locating accurately.
A second method involves punching precise holes near the ends of the
separate, individual sections, such that they overlap when positioned
correctly. This has the advantage that individual sections can be used, that
are easy to handle even for large panels. The disadvantage is that some
method of pinning through the holes at each corner must be employed to
allow the parallelogram to go to the next stage of securing one angle.
A precise angle can be formed in two manners. Firstly an angular template
or jig can be used. Secondly if reference points are formed at a known
distance from the corner, then setting the diagonal distance between these
reference points determines the angle by Pythagoras' theorem. The
disadvantage of a template or jig is that a large tool would be required to
form an accurate angle. The advantage of using a Pythagoras triangulation is
that reference points can take the form of very accurate holes punched in the
section during rolling. The correct angle can then be achieved by moving the
frame (which will pivot either about the tabs or pinned holes) until a linear
tool of known dimensions fits into the holes. Any error in the dimension of
the reference tool will become an error in the apex angle. This error will be
inversely proportional to the proximity of the reference holes to the apex.
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The first method of locating adjacent sections is demonstrated in Figure 2
where a single continuous cold rolled section, preferably of metal, has a
length equal to the perimeter of the intended frame (with perhaps some minor
adjustments for stretching during subsequent bending). This section has
provision for three bends to be made in it, by means of pairs of notches 1, 2,
and 3 in opposite sides of the channel section and extending into the base. At
least two reference positions, in the form of holes 4, 5, are formed in the
sides of separate segments 6, 7, 8, 9, here in end segments 6 and 9, rather
than in two adjacent segments. With modern section rolling equipment, these
notches and reference holes can be located with great accuracy.
Consequently, to achieve the required geometry it will be sufficient to bend
the section as shown in Figure 3, such that the two reference points are a
certain absolute distance 10 apart. This can be ensured with the simples of
reference tools 11 as shown in Figure 4, having spaced pegs 12 at a
predetermined distance apart to fit in holes 4, 5 when the segments 6 and 9
are at 90°. An alternative reference tool 13 could comprise both
angular and
linear information such as shown in Figure 5, for a right-angled corner of the
frame. Of course for other angles set by tools 11 or 13 the distance 10 is not
a hypotenuse of the triangle defined by the tool and the two frame sides, but
merely the third side.
The location of the reference holes 4, 5 in the section could be a function of
the frame perimeter such that regardless of the design, the final distance 10
between the holes would be a constant. This would allow the use of the same
linear reference tool 11 on all panel designs, thus further reducing the lead
times for a new design. Whilst the reference positions, such as holes 4 and 5,
are preferably produced during the (cold) rolling process which forms a strip
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into the section or segment (side), this is not essential, and could be
effected
in a secondary, later operation.
The design of the notch that locates the bends between the segments can be
varied to accommodate a number of different joining techniques, section
profiles and material thicknesses. The simplest design would involve a
channel or U section with notches cut either side of the base as shown in
Figure 2. The notch dimensions should be chosen carefully. If the notch is
too wide then the location of the bend may be vague and accuracy will be
lost. If the notch is too narrow the bend may be too tight resulting in the
channel sides fouling and not allowing a full ninety degrees to be achieved.
It
would be possible to design more sophisticated notches. For example, the
central portion of the notch could be narrow to allow a tight accurate bend,
whilst the notch 14a in the area of a side (Figure 6) could be angled to allow
a mitred joint 14b as shown in Figure 7. This would mean that the joint
surface would be flush providing a good mounting for any subsequent board
application. However, most joining techniques require a degree of overlap of
the segments which means that the design of the notch may need to take
account of the section that the material will be formed into. For a simple
channel section, little provision needs to be made to allow the fold to take
place. If however, the section is of 'C' section with returns 15 (Figures 8 to
10) on the channel sides (which have greater load bearing capabilities), some
provision needs to be made as shown in Figures 8 to 10 to allow the section
to be bent without the returns fouling.
It is also possible to facilitate the accurate and easy bending of the section
by
punching fold lines or perforations along the intended fold. Care must be
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taken however, not to weaken the section so that handling of the component
becomes difficult prior to forming into a frame.
To avoid the overlapping regions of the bent corners from distorting the
application of boards to the panels, these regions 16 can be swaged so that
they are flush as shown in Figures 11 and 12. This can be done either in line
or as a separate pressing operation.
In the overlap areas of the section, it is possible to punch congruent holes
17
that overlap when the segments are bent to the correct angle (or the end
segments link up correctly) as shown in Figures 13 and 14. Instead of two
overlapping holes, two printed dots or a hole aligning with a printed dot
could be used. Thus any suitable alignment means could be used. There are
numerous alternative methods of securing the overlapping regions, and the
choice will depend on the application, speed required, expense and whether
assembled on site or in the factory. Possible joining techniques include,
welding (e.g. butt welding mitred joints or spot welding overlapping areas),
riveting and clinching. To ensure maximum accuracy, the head of the joining
tool can be modified such that the join can only take place once one or more
locating pins on the tool is located through the two overlapping holes thus
further ensuring the accuracy of the individual joints. This tool assembly can
be extended such that it incorporates the linear and furthermore, the angular
references in its structure. Such an assembly, when used in conjunction with
the joining procedure, would reduce the total registration and joining to a
single operation. In an extreme case, the linearly spaced holes 4 and 5 of
Figures 4 and 5 could be positioned so that the spacing is zero, thus
providing the reference in the same form as in Figures 13 and 14. The
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reference tool is thus now, in effect, a single peg through the two aligned
holes rather than two pegs. Moreover, for example with a rectangular frame,
such as A, the reference positions, i.e. holes 4, 5, in two adjacent sections
could be spaced fully away from their common notch, so that the distance 10
is a diagonal of the frame. The holes 4, 5 thus each coincide with different
holes 17, and can thus replace them, serving both to locate the sections and
form a precise angle.
As a general rule, the greater the distance 10 between the reference holes 4,
the greater the achievable accuracy. If this distance 10 is reduced to zero,
i.e. the holes overlap as in Figures 13 and 14, it is still possible to
achieve
the desired geometry without any reference tools. However, the disadvantage
of dispensing with the measuring reference completely is the potential loss of
accuracy as a small inaccuracy in the overlap can result in a
disproportionately large error in the desired angle when compared to an equal
error in a larger reference distance. It may thus be preferred to employ
linearly spaced holes 4 and 5 as well as aligned holes 17, in the assembly of
the frame.
Using the combination of an autolocating joining technique and a secondary
angular or linear reference, it is possible to use this framing concept with
totally independent sections rather than a continuous folding strip. This may
be useful should the application demand different types of section to be
formed into frames. However, if either locating mechanism is removed, then
the material must be formed from one (or a combination of) continuous
strips) to reduce the degrees of freedom in the system. It should be noted
that the linear reference holes 4, 5 preferably lie on the two end sections
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unless there are overlapping (or another set) of holes to close the loop.
Otherwise the position of the final joint will be undetermined. The use of
overlapping holes on the closing joint allows the reference dimension to be
the main diagonal of the panel, giving the greatest accuracy.
The concept of using known reference points to locate adjacent segments of
the same frame can be extended to the interconnection of adjacent frames
themselves. A plurality of individual frames can be joined together to form
either larger frames as shown in Figure 15 or more complex assemblies such
as three dimensional modules as shown in Figure 17. Larger frames
themselves can be made using the method described but the use of a number
of smaller frames has the advantages of handling ease and design flexibility -
i.e. a wide variety of large frame designs can be produced using a library of
simple smaller standard frames.
Conventionally, large frames and modules themselves need large complex
jigs for accurate assembly. However, by using sub-frames and components
with known, accurate reference locations 18, such as holes, for locating
(using bolts or autolocating clinching, welding etc.), it is possible to
construct
large complex structures with virtually no jigging whatsoever. For example,
by aligning punched holes of known location, panels or frames can be
extremely accurately positioned with their neighbours as shown in Figures
16a and 16b. This means that on site erection is de-skilled, and also multiple
panels or frames can be assembled into modules with great ease.
The assembly of such panels or frames into module form allows more of the
construction to be done in the controlled environment of a production facility
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rather than a building site. This means that lead times are reduced and
product quality is enhanced.
The simplest method involves the use of a number of identical wall panels or
frames, coupled with appropriate floor and ceiling panels as shown in Figure
17. In this design, there is potentially poor load transfer between the
adjacent
panels or frames 19, 20 to stop the module from twisting. This is potentially
a limitation on the design, as twisting during transit between factory and
site
can damage the decor and interior fittings.
An improvement to this basic concept is to ensure that the panels or frames
on the roof and floor do not align to those on the walls as shown in Figure
18. This overlapping offers greater structural integrity than the previous
designs as the end of each panel acts as a tie between the segments of the two
panels that are attached to the ends of it. This therefore acts to prevent the
panels from distorting.
However, any given module concept can either be constructed using
conventional methods with individual sections (and therefore requiring jigs
for the panels and further jigs to assemble these panels into modules) or by
using the in-built geometry method of making sub panels. Indeed, the jig-less
framing technique can be further extended to facilitate the assembly of three-
dimensional modules without the need for three-dimensional jigging. By
including reference holes or notches to align the faces of adjoining panels as
shown in Figures 16a and 16b, the accuracy of their location is ensured. In
particular, if a tool is used that aligns the holes and joins simultaneously,
the
assembly process is once again substantially simplified.
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The locations of all the holes, notches, folds and cuts can be a pre-
determined
function of the overall module (or just the panel) dimensions. It is possible
to
formulate simple design rules that take certain input parameters such as
module length, height, floor loading (to determine the floor section depth)
and horizontal centre spacing (to increase the module stacking height, the
distance between vertical struts can be reduced) and automatically generate
all the production parameters. This therefore substantially reduces the amount
of detailed design work required; further reducing costs and lead times.
At the other extreme, having significantly de-skilled the assembly process, it
is now possible to supply modules in kit form to be assembled on site. Kits
can be supplied with pre-punched sections ready to assemble into sub-panels
and subsequently into modules with great ease and speed. One of the
limitations of section rolling is that the minimum length of a cut section
tends
to be longer than often required for some of the short members found in
panels. Conventionally, panel assembly is possible by manually cutting
standard section lengths into shorter lengths. This process is very labour
intensive and prone to error. It is however possible to insert precision
notches
into the section such that the section is segmented into lengths of pre-
determined size. Therefore the overall strip is of a length suitable for
automated cutting, but each segment of the section can be easily snipped to
form a plurality of shorter individual sections. Each segment is punched with
all the geometric locating holes necessary to quickly form the desired frame.
If necessary, each segment can be marked during rolling so that each is
identifiable after snipping with a product number, orientation etc.
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Transported in this form, it is possible to efficiently supply a large number
of
rapid assembly modules, which is useful in situations such as disaster relief.
Continuous sections ready for folding into frames can be transported using
much less space, and strips segmented ready for snipping into short lengths
reduce the risk of loss or damage to components.
Another example where kit form may be advantageous is in the supply of
roof trusses. Here a large number of trusses can be supplied on the back of a
lorry in section form, flat packed ready for folding and fixing on site.
Either
a simple triangular truss 21a as shown in Figure 19 or a double triangle truss
21b with supporting central strut as shown in Figure 20 can be assembled
from a single continuous section with no reference tooling, given that the
predetermined hinge locations are sufficient to define the geometry.
Another example of a non-square frame made from a continuous section is a
pentagonal frame for use in the assembly of small structures such as
greenhouses as shown in Figure 21. However, two reference dimensions e.g.
22 and 23 are required here to ensure the correct geometry. A similar result
with only one reference 24 can be achieved using a four member asymmetric
frame that provides for an inclined roof as shown in Figure 22.
An asymmetric frame can visualise some of the advantages that are inherent
in this concept. To make a number of panels of subtly varying dimensions
requires nothing more than inputting the data into the computer that controls
the section rolling mill (which can be part of a fully automated sales order
processing process to further streamline the manufacturing process). As a
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result, complex structures (e.g. gradually inclining roofs) can be
accommodated with ease.
As mentioned, it is possible to use the concept either in individual component
form or for ultimate assembly ease, using a continuous segmented strip. It is
also possible to combine elements of both an example of which is shown in
Figures 23 and 24. Here, a continuous segmented strip 25 is used as the core
of a lattice beam structure in conjunction with two external sections 26, 27.
In this example, the hole positions are calculated so that the holes 28 in the
segmented strip relate to the holes 29 punched in the individual sections.
Although metal is the preferred material for the methods described, wooden
segments/sections could alternatively be used as the structural members.
It has been described how, by taking advantage of the computer controlled
programming of modern section rolling equipment, the manufacture of a
wide variety of frames and panels is facilitated by alterations in the
software
domain, rather than in tools and hardware. A method has been presented
whereby geometric information traditionally embedded in an external
reference frame, is in fact engineered in the product itself during
production.
Consequently the costs associated with the manufacture of such products is
drastically reduced, as are the respective lead times.
In summary therefore, cold-formed sections for use in the construction of
frames and panels are rolled from sections that have inherent geometric
features that relate to the desired geometry of the resulting frame or panel.
These sections can be formed into a frame using typically only one-
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dimensional reference (angular or linear) and no external jigging or clamping
to produce an accurate component. Thus, a large variety of products can be
manufactured quickly and accurately without the need for complex and
expensive hardware or manufacturing tools. Such sections can be formed
into panels which can be supplied in kit form to site, or can be accurately
assembled without jigs into modules that can be fitted out if required prior
to
site delivery.
