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TITLE
Fabricating a Metal Beam
DESCRIPTION
Field of the Invention
The invention relates to methods of fabricating metal beams as structural building
members in building construction. The beams, made by cutting and welding from flat
metal sheet material, can have the final form of an I-section beam or a box section
beam without incurring the expense and weight associated with hot rolled beam
components.
Background Art
It is known to construct actual building members from sheet steel by a cold rolling
process. It is also known that the strength of such building members can be increased
by welding or brazing reinforcing steel sheets across known profiles to create
reinforced profiles. For example, the strength of sheet steel cold-rolled into a C-
section can be increased by welding face plates at intervals across the open edge of
the C-section. A combination of cold-rolling and welding or brazing is therefore well
known as a method of fabricating lightweight metal beams with good structural
strength.
If the cold-rolling step is omitted, then the fabrication of a beam relies wholly on the
welding or brazing process. It is necessary to hold the component panels in a very
strict alignment one relative to the other while welding or brazing takes places, and
the setting up time prior to welding or brazing is therefore very significant.
It is an object of the invention to provide a simpler method of fabrication that would
create, from flat sheet metal components, a metal beam comprising two face plates of
sheet steel held mutually spaced apart by a reinforcing web or webs extending
perpendicularly to each of the face plates and secured thereto by welding or by
brazing.

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The Invention
The invention provides the method of fabricating a metal beam as specified in claim
1. Those edge portions which extend completely through the face plates as projecting
lugs may be gripped by pliers, for example by one man working alone, and twisted so
that they cannot retreat back through the slots through which they extend. In this way
a temporary fixing can be obtained, with the reinforcing web extending
perpendicularly to the face plates and holding them spaced apart and preferably
mutually parallel one to the other. While thus temporarily retained, the face plates
can be welded or brazed to the supporting web. That welding or brazing can be from
the outside face of the face plates, being the side on which the projecting lugs extend
through the slots; or it can be the inside edge junction, where the reinforcing web was
initially presented up to the row of slots in each face plate.
The fabrication of the face plates and of the reinforcing web can easily be achieved
using a laser cutter. The laser cutter can cut the rows of slots quickly and accurately.
It can also cut the longitudinal edges of the reinforcing web into a crennelated shape,
so as to create the array of edge projections sized and spaced to engage with the slots
in the face plates.
The line of the junction between the reinforcing web and the face plates may be linear
or non-linear. Preferably it is non-linear, because that adds strength and rigidity to the
final beam. For example, even if the face plates are long plates of rectangular shape,
the reinforcing web preferably extends other than longitudinally along the centre of
the face plates. Preferably the reinforcing web extends in a zig-zag or sinuous path
along the length of the face plates, passing alternatively from one side to the other of a
longitudinal centre line of the beam.
The face plates do not have to be long and rectangular in shape. They could be cut
into a flat annular or part-annular curve or arc, with the reinforcing web following
generally the centreline of the curve or an outer and/or inner edge of the curve but

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preferably spaced slightly inwardly from that edge. Along that intended line of
engagement between the face plate and the reinforcing web, the laser cuts a row of
slots into the face plate. The reinforcing web is then presented up to that arcuate row
of slots, bending it as appropriate until the edge projections of the reinforcing web
extend into or through the slots in the arcuate row. A sufficient number of the edge
projections are sized to pass as lugs completely through the slots with which they
engage to ensure that as long as those edge projections or lugs extending through the
face plates are sufficiently regular and close together to hold the assembly together,
then the twisting or bending of the lugs is sufficient to create a robust temporary
retention.
Drawings
Figure 1 is a plan view from above of an arcuate metal beam of box section
constructed by the method of the invention;
Figure 2 is a section taken along the plane A-A of Figure 1, showing the box
construction of the finished beam;
Figure 3 is a perspective view of a portion of the beam during construction;
Figure 4 is a plan view from above of another beam according to the invention, being
a longitudinal beam with a reinforcing web extending the length of the beam in a
sinuous manner;
Figure 5 is a perspective view of the beam of Figure 4;
Figure 6 is a detailed view of one edge of a reinforcing web of a beam according to
the invention; and
Figure 7 is a perspective view of a portion of the edge of a box section metal beam
during the fabrication method of the invention, with one of the edge projections of the
reinforcing web extending through a slot formed in the top face plate and twisted to
achieve temporary retention of the face plate on the reinforcing web.
Referring first to Figures 1 to 3, there is shown in Figure 1 a beam of box section that
is a complete semi-circle. That is to say, a top face plate 2 and a bottom face plate 3
are each semi-circular and annular in shape. That shape can be achieved with
minimal stock wastage by constructing the semi-circle from six sectors which fit

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together with laser-cut dovetail joints. The joint lines 4 between the adjacent sectors
are welded or brazed together as a final step at the end of the fabrication process, as
described below.
Parallel to each edge of the semi-circular face plates, and slightly spaced from that
edge, is a row of laser-cut slots 5 depicted schematically in Figures 1 and 3 by broken
lines. Each row of slots 5 follows a line which is the intended line of engagement
between the respective face plate 2 or 3 and a reinforcing web 6. Each reinforcing
web 6 is cut from a flat sheet of metal and has opposite parallel edges cut into a
crenellated shape as shown in Figure 6. That crenellation forms the edges of the
reinforcing plates into a linear array of edge projections 7 which are accurately cut so
as to fit closely into the laser-cut slots 5. Some of the edge projections 7 pass
completely through the slots and extend as lugs 8 above or below the associated face
plates as shown in Figure 3, and are twisted so as to provide a temporary anchorage
between the enforcing web and the face plates. That twisting is shown in Figure 3,
and can readily be achieved by one man working with a pair of pliers only. Because
the reinforcing webs extend close to the outer and inner curved edges of the semi-
circular beam, the resultant box section has considerable structural rigidity.
From the temporarily retained condition of Figure 3, the face plates 2 and 3 are
welded or brazed to the supporting web 6 along the line of engagement therebetween.
For example mat line of welds or brazes could be a series of spot welds or spot brazes
shown at 9 in Figure 3, along the inside edge between the abutting face plates and the
reinforcing web. Alternatively the spot welds or spot brazes could be along the top
and bottom faces of the respective face plates 2 and 3. The non-linear shape of the
reinforcing web 6 gives the resulting beams optimum strength. Preferably it is at this
stage, after assembly, that all excessive metal projecting above the outer faces of the
face plates, including the twisted edge projections which form the temporary retention
of the face plates on the reinforcing web, are removed by grinding.
Figures 4 and 5 show a similar construction of a fabricated beam in which the face
plates 2 and 3 are generally long and rectangular, and the reinforcing web 6 runs

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longitudinally down between them, passing from near one side to near the other side
for maximum strength.
Figures 6 and 7 show in more detail the edge projections of the reinforcing web, and
the direction in which the lugs 8 are twisted. Of course that twisting would not take
place until the series of adjacent edge projections 7 had been presented up to the line
of slots 5 in the associated face plate, and would then be bent over only if that edge
projection extended far enough beyond the opposite side of the slot to enable it to be
twisted by pliers.

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CLAIMS
1. A method of fabricating a metal beam for use as a structural building member
in building construction, the metal beam comprising two face plates of sheet metal
held mutually spaced apart by a reinforcing web extending perpendicularly to each of
the face plates and secured thereto by welding or by brazing, characterised in that:
each face plate is formed with a row of slots which together follow a line of
engagement between the face plate and the supporting web;
the reinforcing web is formed along each longitudinal edge with an array of
edge projections sized and spaced apart to engage with the rows of slots to locate the
reinforcing web along the line of engagement with each face plate as defined by the
rows of slots;
at least some of the edge projections are sized to pass completely through the
slots with which they engage, to emerge on the opposite side of the respective face
plates where they are bent so as temporarily to retain the supporting web located
along the line of engagement defined by the rows of slots;
while thus temporarily retained, each face plate is welded or brazed to the
supporting web along the line of engagement therebetween; and
on completion of the welding or brazing, all edge projections of the supporting
web which pass completely through the face plates to stand proud on the other side
are removed by grinding, to finish flush with the outer faces of the respective face
plates.
2. A method according to claim 1, wherein the bending of the edge projections
which pass completely through the face plates is achieved by twisting the edge
projections.
3. A method according to claim 1 or claim 2, wherein the rows of slots are cut
into the face plates using a laser cutter.

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4. A method according to any preceding claim, wherein the edge projections of
the reinforcing web are created by cutting the reinforcing web from a sheet of metal
using a laser.
5. A method according to any preceding claim, wherein the reinforcing web is
non-linear.
6. A method according to claim 5, wherein the face plates are curved and the
reinforcing web extends in an arc along one edge of the curve.
7. A method according to claim 5, wherein the face plates are curved and the
reinforcing web extends in an arc along a centreline of the curve.
8. A method according to claim 5, wherein the face plates are curved and the
reinforcing web extends in an arc along an outer edge of the curve, with a similar non-
linear reinforcing web extending along an inner edge of the curve and assembled in a
similar manner to create an arcuate beam of box construction.
9. A method according to claim 5, wherein the face plates are long plates of
rectangular shape and the reinforcing web extends in a zig-zag or sinuous path along
the length of the face plates, passing alternately from one side to the other of a
longitudinal centreline of the beam.

Method of fabricating a metal beam from flat metal components (2, 3, 6). Two face plates of sheet metal (2, 3) are
held mutually spaced apart by a reinforcing web (6) which is perpendicular to each of the face plates (2, 3) and which preferably
extends in a non-linear path. Each face plate (2, 3) is formed with a row of slots (5) which together follow a line of engagement
between the face plate (2, 3) and the supporting web (6). Each longitudinal edge of the reinforcing web (6) is formed as an array
of edge projections (7) sized and spaced apart to engage with the slots (5) in the respective face plate (2, 3). Some of the edge
projections (8) are sized to pass completely through the slots (5) with which they engage, and are bent preferably by twisting to form
a temporary retention between the supporting web (6) and the face plates (2, 3). Whilst thus temporarily retained, each face plate
(2, 3) is welded or brazed to the supporting web (6) along the line of engagement therebetween. Finally all edge projections (8) that
stand proud on the other side are removed by grinding. The resulting metal beam can be an I-section beam or a box section beam.