Note: Descriptions are shown in the official language in which they were submitted.
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67P9CA
SLAB FORMWORK SYSTEMS
The present invention relates to slab formwork systems and is useful in
particular, but
not exclusively, for formwork systems for use in casting concrete ceilings.
In the construction of concrete buildings, it is known to employ, for the
casting of
ceilings, a slab formwork comprising panel support beams mounted on shores and
panels
supported on the panel support beams. It is further known to provide the
shores with
dropheads, which support the beams and which also have heads projecting
between the
panels. In use, after a concrete slab has been cast on the panels and the
concrete of the slab
has sufficiently hardened, parts of the dropheads carrying the beams and
panels can be
released for movement downwardly relative to the shores, thereby allowing the
beams and
the panels to the withdrawn downwardly from the newly cast concrete. The heads
of the
dropheads remain in position to support the concrete. An example of such a
prior art
formwork system is disclosed in United States Patent No. 5, 614,122, issued
March 25,1997
to Artur Schwoerer.
According to the present invention, there is provided a slab formwork system
comprising formwork panels, panel support shores, dropheads mountable on the
tops of the
panel support shores, panel support beams for underlying the formwork panels,
the panel
support beams being engageable with the dropheads for supporting the panel
support beams
on the dropheads and the panel support beams being telescopically
longitudinally adjustable
to allow corresponding variation of the spacings of the shores on assembly of
the system.
Preferably, the panel support beams have telescopically extendable extension
members and
fasteners for securing the extension members relative to the panel support
beams, the
dropheads having bearing members for supporting engagement with the extension
members.
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In a preferred embodiment of the present invention, the panel support beams
have upwardly
facing top surfaces, upwardly open, longitudinally extending recesses between
the top
surfaces and resiliently deformable strips of elastomeric material extending
along the
recesses and the formwork panels have downwardly protruding panel retainer
projections
embedded in the resiliently deformable strips.
The embedding of the panel retainer projections into the resiliently
deformable strips
counteracts undesired displacement of the panels longitudinally of the panel
support beams
and thereby substantially stabilizes the assembly of the panels on the beams
and shores.
The panel retainer projections and preferably are tapered so as to urge the
adjacent pairs of
panels towards one another as the panel retainer projections become embedded
in the strips.
Consequently, as the panels are mounted on the panel support beams, the panels
at opposite
sides of each panel support beam are automatically drawn together so as to
reduce or even
effectively eliminate any gaps between opposed edges of adjacent panels.
In the preferred embodiment of the present invention, the formwork panels each
have a pair
of parallel, elongate side members, elongate intermediate members extending
between and
interconnecting the side members and a sheet of material supported on the side
and
intermediate members, and the side members have undersides formed with a
longitudinally
extending, downwardly open recesses. Connecting clips retained in the
downwardly open
recesses are engaged with the panel support beams to secure the formwork
panels to the
support beams.
In this embodiment, the panel support beams are telescopically longitudinally
adjustable to
allow corresponding variation of these spacings of the shores, which have
dropheads and the
dropheads each have a first component forming a prop extending between an
adjacent pair
of the formwork panels and a second component in supporting engagement with
the
formwork panels. The first and second components having mutually engaged screw
threads
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allowing the second component to be lowered gradually and gently, by an easily
controlled
amount, relative to the first component for releasing the formwork panels
without damage
to the components of the system.
The invention will be more readily understood from the following description
of an
embodiment thereof given, by way of example only, with reference to the
accompanying
drawings, in which:-
Figure 1 shows a view in perspective of a partially-completed slab formwork
according to
a preferred embodiment of the present invention;
Figure 2 shows a broken-away view of a pair of beams mounted on a dropheads
forming part
of the slab formwork system of Figure l;
Figure 3 shows a view, taken at right angles relative to that of Figure 3, and
illustrating parts
of panel support beams and panels supported by the drophead;
Figure 4 shows a view in perspective of the drophead of Figures 3 and 4;
Figure 5 shows a view in perspective of a displaceable component of the
drophead of Figure
4;
Figures 6, 7 and 8 show views in side elevation of a panel support beam
forming part of the
slab formwork system of Figure 1 in retracted, partly extended and fully
extended conditions,
respectively;
Figures 9 and 10 show views in perspective of an end component of the
telescopic panel
support beam and an end portion of the support beam shown in Figures 6, 7 and
8;
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Figure 11 shows a view taken in vertical longitudinal cross-section through
the telescopic
panel support beam of Figures 6, 7 and 8;
Figure 12 shows a broken-away view of parts of one of the panels of the slab
formwork
system of Figure 1.
Figure 13 shows a view in vertical cross-section through adjacent edge
portions of a pair of
panels mounted on an upper portion of a panel support beam in the slab
formwork system
of Figure 1; and
Figures 14A and 14B show views in perspective of a connecting clip and a panel
retainer
projection, respectively, of the apparatus of Figure 13.
The slab formwork system 10 has panel support beams 12, which as described in
greater detail below are of hollow cross-section and longitudinally
telescopic, arranged in
parallel rows and mounted on dropheads, indicated generally by reference
numerals 14,
which in turn are mounted on the tops of the shores 16. Filler beams 18, which
may
conveniently be formed of 2 x 4" lumber, extend at right angles to the panel
support beams
12 between the parallel rows of panel support beams 12 and are supported at
opposite ends
of the beams on the dropheads 14. Panels 20 are mounted on the panel support
beams 12
between the filler beams 18.
Figure 2 shows the ends of a pair of the filler beams 18 mounted on one of the
dropheads 14, which is described in greater detail below with reference to
Figures 2 -5 of the
accompanying drawings.
The drophead 14 comprise is a first component, indicated generally by
reference
numeral 22, which is fixed relative to its respective shore 16, and a second
component, which
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is indicated generally by reference 24 and illustrated in Figure 5, and which
is vertically
displaceable relative to the first component 22, as described below.
The second component 24 of the drophead 14, as shown in Figure 5, has a tube
or
sleeve 26 which, at its upper end, is provided with a pair of support
brackets, indicated
generally by reference numeral 28 projecting from opposite sides of the sleeve
26. The
second component 24 also has two pairs of parallel bearing plates which are
indicated
generally by reference numerals 30, and which project from opposite sides of
the sleeve 26
at right angles to the support brackets 28.
The first component 22 of the drophead 14 has a tubular portion 32 welded to a
base
plate 34, and a screw 36 extending upwardly from the tubular portion 32. The
base plate 34
is fixed to the top of the shore 16 by nut-and-bolt fastener 33, as shown in
Figure 3. A T-
shaped prophead, indicated generally by reference 38, is mounted on the top of
the screw 36
and is formed by a vertical member 40 extending from the screw 36 and welded
to a
horizontal member 42 to form a T-bar, the vertical and horizontal members 40
and 42 being
formed by metal tubes of rectangular cross-section.
A nut 44 in threaded engagement with the screw 36 is formed with handles 46 to
facilitate rotation of the nut 44 relative to the screw 36. The nut 44 is in
sliding contact with
a bearing ring 48 at the lower end of the sleeve 26.
As can be seen in Figure 2 , the filler beams 18 extend from opposite ends of
the
horizontal member 42 of the prop head 38 and the tops of the filler beams 18
are flush with
the top of the prop head 38. The vertical member 40 of the prophead 38 is
provided with
laterally protruding jam plates 45, which are spaced downwardly from the
horizontal member
42, and project at right angles relative to the horizontal member 42. These
jam plates 45 abut
the top of the sleeve 26 when the top of the prophead 38 is flush with the
tops of the filler
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beams 18. As shown in Figure 1, the filler beams 18 extend between adjacent
pairs of the
panels 20.
Figure 3, which shows a view of the drophead 14 taken at right angles to that
of
Figure 2, illustrates a pair of the panel support beams 12, which are each
provided at opposite
ends with beam extension members 50 (see Figures 6-8), supported on the
bearing plates 30
at opposite sides of the sleeve 26, with the panel support beams 12 extending
at right angles
to the filler beams 18.
More particularly, with reference to Figures 6-8, the beam extension members
50
are telescopically engaged in the beams 12 and are each formed with five
transverse bolt
holes 52. Pins 54 extend through outer ends of the beam extension members 50
and rest on
the bearing plates 32 to support the beam 12 on the drophead 14. As can be
seen from
Figure 5, each bearing plate 30 is formed with and upwardly open recesses 56
for receiving
and retaining the pins 54.
The panel support beams 12 are also formed with transverse bolt holes 58,
through
which bolts 60 can be inserted, these bolts 60 also extending through
corresponding bolt
holes 52 in the beam extension members 50 to retain the latter in position
relative to the
panel support beams 12. By this means, the beam extension members 50 can be
drawn into
the beams 12 into retracted positions, as shown in Figures 6 and 9, or into
partly extended
positions, as shown in Figure 7 or into fully extended positions, as shown in
Figures 8 and
10, and locked in these positions.
Figure 3 also shows the panels 20 supported on the panel support beams 12,
with the
filler beams 18 extending between adjacent panels 20 between of the drophead
14 and with
one of the brackets 28 extending between and upwardly from the tops of the
beam extension
members 50 support one of the filler beams 18.
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Figures 9 and 10 show broken-away views of an end portion 66 of one of the
support
beams 12, which is reinforced by longitudinally extending, transverse internal
webs 68. The
webs 68 are located above and below, respectively, the bolt holes 58 to avoid
obstructing
the bolts 60.
As shown in Figures 13 and 14, the panel support beam 12 is formed with spaced
side walls 80 connected by upper and lower webs 82 and 84. In addition, the
panel support
beam 12 has, at its top and bottom, webs 86 connecting the sidewalk 80 and the
top and
bottom webs 82 and 84 to laterally outwardly projecting flanges 88 and
laterally inwardly
extending flanges 91, and the flanges 91 define an upwardly open,
longitudinally extending
recess 92 in the top of the panel support beam 12 and also in the bottom of
the panel support
beam 12. In the uppermost recess 92, there is provided a resiliently
deformable insert or
strip 94 of elastomeric material, and the inwardly extending flanges 91 are
formed with
steps 96 engaging and retaining the resiliently deformable strip 94 within the
uppermost
recess 92.
As can be seen from Figures 9 and 10, the beam extension member 50 has an
upper
portion, indicated generally by reference numeral 95, which has a cross-
sectional shape
similar to that of a corresponding upper portion of the support beams 12, i.e.
is formed of
portions which correspond to the upper web 82, webs 86, flanges 88 and 91,
recess 92 and
lip 130, and which for convenience are indicated by corresponding reference
numerals with
the suffix "A" added. An insert 94A of elastomeric material, corresponding in
cross-
sectional shape to the elastomeric material strip 94, is inserted into the
recess 92A.
The panels 20 are formed of parallel, elongate side members in the form of
extrusions 100, (Figure 12) which are interconnected by elongate intermediate
members,
in the form of extrusions 102, and plywood sheets 104 are mounted on the
extrusions 100
and 102. The extrusions 100, as shown in Figure 12, have recesses 106, which
have
opposite side walls 107 and are downwardly open between opposed flanges 108.
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At the adjacent edges of adjacent panels 20, the recesses 106 receive panel
retainer
projections 110, which are secured in position relative to the extrusions 100
by bolts 112
extending through the sidewalk 107 of the recesses 106 and through the panel
retainer
projections 110.
The panel retainer projections 110 are formed as rectangular blocks 111
(Figure
14A) having downwardly protruding nose portions 102 which, as shown in Figure
13, press
into and are thereby embedded in the resiliently deformable strip 94. This
embedding of the
nose portions 102 of the panel retainer projections 110 in the resiliently
deformable strip 94
prevents the panels 20 from sliding laterally of the panels, i.e.
longitudinally of the panel
support beams 12, and also ensures stability of the assembly of the panels 20
and the beams
12. Also, the engagement of the panel retainer projections 110 in the recesses
92, between
the flanges 90, secures the parallel rows of the beams 12 relative to one
another. The nose
portions 102 have flat, vertical opposed faces 114 (Figure 14A), which are
located adjacent
one another, and opposite outwardly and upwardly inclined faces 116 at their
sides opposite
from the faces 114. The faces 114 and 116 merge smoothly with convexly curved
lowermost surface portions 118. As a result of the inclination of the surfaces
114, the nose
portions 102 are downwardly tapered so as to urge adjacent pairs of the panels
20 toward
one another as the nose portions 102 of the panel retainer projections 110 are
inserted into
the recesses 92 and thereby pressed into and embedded in the resiliently
deformable strip
94.
In addition, the provision of the resiliently deformable strip 94 in the
recess 92 at the
top of the beam 12 prevents the entry of concrete past the flanges 90 into the
recess 92,
during use of the slab formwork system 10, thereby avoiding any necessity to
remove such
concrete after the casting of a slab in order to prepare the panel support
beam 12 for a new
casting operation.
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Referring now to Figures 13 and 14B, there is shown a connecting clip
indicated
generally by reference numeral 120, which is formed by a retainer member 122
which is U-
shaped and which is retained by a bolt 124 and a nut 126. The bolt has a
rectangular-
elliptical head 128, which is received in the recess 106 of the extrusion 100,
so that on
tightening of the nut 126, the retainer member 122 is clamped into engagement
with the
underside of the extrusion 100 and with the panel support beam 12. More
particularly, the
outwardly extending flanges 88 of the panel support beam 12 are each formed,
at their
outermost ends, with a depending lip 130, and the retainer member 122 has a
flange 132
which engages between one of the lips 130 and the adjacent flange 86 of the
panel support
beam 12. Consequently, by means of the connecting clip 120, the associated
panel 20 is
locked in position relative to the panel support beam 12.
As will be apparent to those skilled in the art, various modifications may be
made in the
above-described embodiment of the present invention within the scope of the
appended
claims.
