Note: Descriptions are shown in the official language in which they were submitted.
FIELD OF THE INVENTION
The present invention relates -to a device and method for
supporting a structure during construction operations to
permit the structure ~o ~e formed into a curved shape. For
example, the invention can be applied to the formation of an
arch during building constructions or to other forming
applications.
BACKGROUND OF THE INVENTION
Conventionally, timber framework is used to support
bricks or stone when an arch is being constructed. When the
mortar has set, the framework is removed by dismantling or
destroying it. In general~ it is not possible to remove a
semi-circular or semi-oval framework from a constructed arch
without dismantling ~he framework on account of the tight
fit between the framework and the arch. If the framework is
to be re-used, it is necessary to expend time and material
in rebuilding it. Clearly such a procedure is expensive and
time~consuming~ particularly when a number of arches of the
same or similar form are to be constructed in succession.
Moreover, if a number of different sized arches are being
built, it is necessary to provide a separate timber
framework for each arch style or size.
Australian Patent Specifications 264,747 (J. Bossner),
255,593 (J. Bossner) and 112,247 (W. A. Porter) have
disclosed various arrangements applicable to the provision
of a support construction relating to formwork for hollow
bodies such as concrete hollow bodies, the formwork
including internal formwork adapted to be inwardly retracted
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for removal from the body when completed. Such designs rely
upon the principle of outwardly displaceable members which
move in a guided manner along a controlled outward path from
a central structure to apply the desired force to support
the formwork. However, such devices are very complex and
very limited in terms of effectiveness, portability,
adaptation to different shapes and sizes and usefulness in
ordinary building operations, whether on a building site or
in factory conditions.
The present invention is directed towards providing a
new and useful device which can be embodied in a most simple
and effective form which can permit the device to be used
for supporting or forming curved structures such a~ arches
and curved strip like members or the likeO
SUMMARY OF THE INVENTION
In one aspectr the present invention is concerned with
an apparatus for supporting during construction operations a
curved structure such as an arch or the like, and in which
the apparatus is adjustable to permit a range of sizes
and/or shapes of a curved structure to be supported or
formed. More particularly~ there is provided a device
comprising a hub member, a multiplicity of struts arranged
to be pivotally connected to the hub member and extend away
from the hub mernber in respective directions which are
independently capable of adjustment relative to one another
and relative to the hub member, and the struts terminating
in means for supporting the material from which the curved
structure is to be constructed, said supporting means being
adapted to be located alony a path corresponding to the
direction in which said curved structure is to extend, and
adjustment means provided to permit alteration of the
effective length of said struts whereby the configuration of
said path may be aLtered, and the device being such that it
may be removed from within the curved structure after
construction has been completed to permit re-use of the
device.
One particularly useful application of the invention is
to support an arch during building constructions, for
example when the arch is formed from bricks or masonry.
However, the invention is not limited to this application
and in this specification the reference to formation of an
arch is to be understood as a reference to forming any
elongated curved construction requiring support during
forming operations.
In a preferred embodiment of the invention, the means
for supporting the arch comprises an elongated band such as
a self-supporting metal strip, which may be flexed to adopt
the desired shape and size for the arch.
The device according to the invention, in general, may
be usable not only for circular openings or part circular
open- ings but also other shapes such as part oval shapes.
Semi~ oval shapes bisected across the minor or major axes of
the oval are possible arch forms which may be constructed
with suitable embodiments of the invention. Furthermore, a
device according to the inven~ion may be used to form more
than a semi-circular openin~ in a structure. For example, a
keyhole shape could be constructed in a brick wall using an
embodiment of the invention.
Preferably, the struts are hingeably connected at
respective locations around a plate-like portion of the hub
member for pivotal motion a~out an axis parallel to the axis
around which the arch is to extend. This permits the angle
of the struts relative to the hub to be varied to suit
different shapes configurations for the arch. Furthermore,
in a preferred and important embodiment of the invention,
the ends of the struts are permanently attached to a
flexible band which is to support the arch. This connection
may be either fixed or hingeable and in a particular embodi-
lS ment some strut~ could be hinged and some fixed. It will be
appreciated that no matter what size this embodiment of the
invention is adjusted to, the flexible band will be
supported at the same regular intervals by alteration of the
position of the struts~
The most preferred form of the invention is one in which
the hub member is of plate-like form and has the struts
pivotally connected at respective spaced locations around
the hub member and the hub member is arranged s~ch that it
may be rotated in order effectively to contract the device
to facilitate its removal when the arch has been formedO It
will be appreciated that the radial distances from the axis
of the h~b member to the pivotal connection with each strut
determines, for a given angle of twisting, the radial
spacing or clearance produced when contraction of the device
occurs.
In the embodiments described with reference to the
drawings, the hub member is a part-circular boss-like
structure but it is pointed out that in principle the boss
could be any convenient shape, for ex~ple square,
triangular, rectangular or star shaped and indeed need not
be plate-like~ In general, any form of structure that will
hold and permit pivotal movement of the struts may be used,
e.g. a bolt.
It will be appreciated that a device in accordance with
the embodiment of Figures l to 4 of the drawings is intended
to be used in the fully expanded condition (for a particular
adjustment of the length of the struts). This is a
configuration which may be considered to be one of unstable
equilibrium so that any slight twisting of the hub member
will tend to cause contraction of the device. Therefore, at
least fcr some applications it mzy be desirable to provide a
locking device for release of the holding the device in its
fully expanded configuration to prevent any accidental
release until the arch has been completed. If the arch is a
brickwork arch then it is necessary to wait until the mortar
has set before removing the device.
Any convenient form of means for adjusting the length of
each strut may be employed but a highly convenient and
effective embodiment is one in which a telescopic connection
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is provided in the middle portion of each strut with
clamping means to hold the desired configuration for a
particular arch shape and size.
To facilite erection, markings can be applied at
appropriate intervals along each strut so that the struts
can be conveniently adjusted before the device is positioned
in the working configuration.
The device may include a forming strip such as a
flexible spring steel strip for supporting the curved
construction and the strip in turn may be supported from
within the curve by a series of links pivotally connected to
one another to form a chain-like structure and each having
respective convexly curved abutment portions adapted to
engage against the steel strip to support it at a series of
closely spaced locations.
In this embodiment, some of the links can be fixed to
elongated support plates to which outer end portions of the
struts are pivotally connected.
Furthermore, when the device is to be used for forming
e.g. laminated material, the forming strip can be set up
substantially straight and the laminates placed in position
with appropriate resins, and the device embodying the
invention can then be used to place the respective struts in
the desired angular configuration at respective lengths to
form a peedetermined curve and for this purpose the device
preferably includes engagement elements adapted to engage
upon the exterior of the curved laminated material to hold
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it against the for,~ing strip at spaced intervals and this is
preferably achieved by virtue of roller like elements
connected to extend across the laminated material from
extension portions of support pla.es for the links~
S The invention also extends to a method of forming curved
material comprisiny using the device in any one of the forms
described above.
BRIEF DÆSCRIPTION OF THE DRA~7INGS
The invention will be further explained and exemplified
by reference to the accompanying drawings wherein;
Figure 1 is a perspective view schematically illustrat-
ing a first embodiment of a support device;
Figure 2 shows the support device being removed from a
completed arch;
Figure 3 shows to an enlarged scale the hub of the
support device;
Figure 4 shows a detail of Figure 3;
Figure 5 shows in partial cross-section a telescopic
spoke.
Figures 6 to 8 show various ~urved dispositions of the
support device;
Figure 9 shows schematically a support device capable of
alteration into different curved forms;
Figure 10 is an illustration of a further embodiment for
forming laminated material into a curved arch and adapted to
incorporate the support device of the first embodiment; and
Figure 11 is a cross~sectional elevation t~ken along the
line XI-XI of Figure 10.
DET~ILE~ DESCRIPTION OF T;~E DRA~ GS
The support device shown in Figures l to 4 has
telescopic spokes 3 which are shown in detail in Figure 5.
The support device as shown in Figure 1 comprises a curved
peripheral band 1 connected to a semi-circular hub 2 by
means of a multiplicity of spokes 3 pivotally connected to
the hub at spaced positions a~jacent the periphery of the
hub. At their outer ends, the spokes 3 are welded or other-
wise attached to the inner surface of the curved band 1,
which conveniently can be in the form of a mild steel strip,
for example of cross-section 100mm x 7 mm. The spokes 3 are
composed oE steel bar, for example 12 mm square bar~
Figure 1 shows an example of a spoke 3A having a pivotal
connection to the flexible band L. Generally the
connections between the spokes and band 1 can either be
pivotal or fixed, although if fixed connections are use~
then in practice only a limited degree of change in the
curvature of the band can be achieved.
Operation of the device is shown schematically in Figure
2. The support device is initially secured in a selected
expanded state (shown in Figure l) either by resting the
base of the hub l on scaffolding so as to prevent it
rotating or by providing a locking means (not shown) to lock
the position of at least one of the spokes 3 relative to the
hub 2. An arch of bricks 4 is then built around the outer
periphery of the curved band 1. The completed arch is shown
in Figure 2 which also shows how the device is removed from
the arch after the mortar between the bricks has set hard~
lhe hub 2 is twisted in an anticlockwise direction as shown
by the small arrows so as to cause the radius of curvature
of the curved band 1 to decrease and to open up a gap G
between the curved band and the arch. This enables the
contracted support device to be removed from the arch in the
downward direction. The support device may be reused by
simply twisting the hub 2 clockwlse so as to restore it to
the position shown in Figure 1.
Figures 3 and 4 illustrate in greater detail the pivotal
connection of the spokes 3 to the hub 20 The inner end of
each spoke 3 comprises a yoke 5 embracing either face of the
hub 2 and pivotally mounted thereon by means of a pin 6.
Figure 5 illustrates the form, in detail, of a
telescopic spokes 3, which comprises an inner square bar
portion 8 slidable into an outer square sleeve portion 7 so
as to vary the length of the spoke. There are marks on the
inner portion 8 enabling the length of the spoke 3 to be
easily and reproducibly reset for providing various spoke
lengths. A locking device is provided for locking together
the portions 7 and 8. The locking device comprises an
internally threaded element 3 welded to the outer sleeve
portion 7 and a threaded shank 10 having attached thereto a
hand wheel 11 for clamping the spoke at a desired position.
The outer end of the portion 7 is shown welded to the
inner surface of the curved band 1. However, when large
variations in the radius of the curved band are to be
allowed for, it is preferable to hinge the outer ends of at
least some of the spokes 3 to the curved band 1~
Figures 6 to 8 show schematically three dif~erent
configurations of a support device for building arches of
circular shape, elongate oval shape (i.e. an oval bisected
along its longer axis) and high oval shape~ The
construction of each of the support devices is, in detail,
based on the same principles shown in Figures 1-50 Thus~ it
will be noted that the hubs 2 follow generally the curved
disposition of the of the curved band 1 in each case.
However, by using spokes 3 of telescopic construction ~as
illustrated in Figure 5), a single support device may be
used to provide all three arch shapes.
Figure 9 shows a further embodiment of support device
having, instead of a rigid hub, a simple pivot link 12
interconnecting the inner ends of the telescopic spokes 3.
Radial contraction and release of the suppor~ device from
the arch may be achieved by radially contracting the spokes
3. The radially contracted disposition is shown in dotted
lines and it will be appreciated that large radial
contraction is possible with this embodirnent not only to
allow for release oE the device from a cornpleted arch, but
also to allow for the construction of arches of greatly
differing radi~s. The telescopic spokes may also be used to
provide arches of non circular form/ similar to those shown
in Figures 7 2nd 8. The marks on the telescopic spokes 3
enable the spoke length ~o be rapidly and reproducibly reset
for a variety of selected arch shapes.
Although the invention has been described in relation to
the construction of arches, it will be appreciated that the
support device has utility in a number of other fields where
support of t~nnels, roofs or doorways is requiredl for
example i.n mines.
A method of forming laminated material into a curved
form will now be described with reference to Figures 10 and
11, which illustrate the initial layup of laminated material
in a straight form before adjustment of the hub ~ and spokes
3 to the desired configuration. The apparatus has a
supporting arrangement for mounting the flexible, peripheral
band 1 on which a laminated workpiece 20 is layed up.
Although not shown in the drawing, the spokes 3 are of the
form shown in Figure 5 and are mounted to a hub 2 as shown
in Figures 1-~.
Each support structure associated with each spoke
comprises side strips 21 pivotally mounted on a bolt 22
either pivotally or fixedly depending on the choice of the
user. Each bol~ 22 extends through a cross tube 3b at the
extremity of the spoke 3 and a fixed link member 24 having
outer cheeks 24a welded to the side strips 21 and
incorporating a profiled block 24b which directly supports
the flexible band 1 and is secured between the cheeks by
pivot pins 24c.
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From Figure 10 it will be apparent that both the support
block 24b and the side cheeks 24a have a part oval shape.
Further pivotal links 25, also comprising side cheeks and a
curved centre support block of the same form as the fixed
links 24, pivotally interconnect adjacent fixed links by
engagement at the piVQt pins 24c, the side cheeks 25a
fitting inside the side cheeks 24a of the fixed links.
A remova~le rotatable roller 26 is provided for mounting
on a bolt 27 at a selected upper location between the side
strips 21, the location being selected so that the roller
bears against the top surface of the layers of laminated
material 20.
The device is intended to be used normally by having the
flexible band 1 flat and horizontal with the rollers 26
remGved. The laminated material such as strips of timber is
layed up with suitable adhesive, the rollers are secured in
position as shown in Figures 10 and 11~ and then the hub is
rotated, if necessary with the application of a suitable
mechanical advantage or hydraulic system or the like, to
contract the structure thereby pulling the flexible band 1
into a predetermined curvature and pulling the laminated
material down to the configuration at which the adhesive is
to cureO Adjustment of the telescopic spokes 3 can also
take place as desired.
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