Note: Descriptions are shown in the official language in which they were submitted.
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Bendable composite Panel
~l~he invention relates to a composite panel
having an elasto-plastically deformable core and at
least one covering layer of a plastically or
thermoplastically deformable material, arranged on one
side. Furthermore, the invention relates to the use of
the composite panel.
Nowadays complex bonding processes with
expensive male aFId female moulds are used for the
produc~ion of be~ or donled composite panels havin~ ~
foalll core of pl~ic. In ~pi~e of the hi~h produc~ion
co~s, the silaping is res~ricted quantitatively and
qualitatively:
- Since special gauges have to be produced for each
shape, the variety of shapes is very restricted.
- For ~he usual bending of composite panels, in the
case of a small bending radius at least one wedge-
shaped groove is made on the inside, which groove
is closed again during bending. According to this
process, the inner covering layer can no longer
fulfil its vapour barrier function.
The present invention is based on the object of
providing a composite panel of the type mentioned at
the beginning which, in a simple way and with short
tlme expenditure, allows flat composite panels to be
subsequently deformed with virtually any desi~ed radii
without significantly reducin~ the composite rigidity
or impairing the vapour permeability.
The object is achieved according to the
invention by at least one covering layer of the
composite panel being preformed and having at least one
bead, running in a straight line and extending over the
en~ire width, ~hich bead or beads allows/allow a
bending of the composite panel with constriction of the
bead/beads.
By geometrically defined beads in one or both
covering layers, according to the invention the cro~s-
section of the composite panel is reduced and space is
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created for bending. The geometrical cross-sectional
shape of the beads is desi~ned in such a way that no
shear overstressing of the core/covering layer
composite occurs during bending. The at least partial
closing of the beads of a covering layer, which are
formed over at least a certain region, has the effect
that the composite panel can be bent or domed or curved
correspondingly, the covering layer having the at least
partially closed beads forming the concavely domed
inner side.
The beads extend in each case over the entire
wid~h o~ a covering layer, where the width is not to be
considered in purely geometrical terms, and beads can
also extend over the entire length of a composite `
panel.
The beads of two opposite covering layers are
preferably offset in the longitudinal direction.
Composite panels having an elasto-plastically
de~ormable core of a thermoplastic or thermoset plastic
must, in spite of their elasto-plastic deformability,
also meet the requirements for mechanical rigLdity
after bending. ~xamples suitable for this purpose are
foams of polyvinyl chloride, Styropor, polystyrene,
polyurethane or polymethacrylate.
Depending on the intended purpose, the core may
be of a closed-pore or open-pore design, and contain
fire-retardant additives, for example aluminium
trihydroxide, and/or mechanically reinforcing fibres,
for example glass fibres or carbon fibres, in a
concentration known to a person skilled in the art.
The thickness of the foam core is preferably in
the range of 20 - 150 mm. Thick cores oppose the
bending force with a high resistance, which could
result in shear overstressing of the corefcovering
layer composite, for which reason the beads have to be
made correspondingly deep. However, the rigidity of
the composite panel must not be reduced too much. Core
layers much less than 20 mm thick are scarcely able to
lend the composite a usually required minimal rigidity.
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The covering layer/layers preferably consists/
consist of a plastically readily deformable metal and/
or a thermoplastic. ~he thickness of the covering
layer/layers is preferably in the range of 0.1
1.5 mm, depending on material and/or use. Metallic
covering layers consist in particular of aluminium, an
aluminium alloy, stainless steel or copper,
thermoplastic covering layers consist of a rigid
plastic, such as for example polyethylene or
polypropylene.
~ he bonding of the covering layers to the core
is performed by means of an adhesive.
With respect to the cross-section, the beads
are expediently designed to be V-shaped, U-shaped,
preferably in each case rounded-off, dovetail-shaped or
pear-shaped. V-shaped beads can be closed over their
full surface area during bending, concavely desi~ned
side surfaces form a cavity during closins due to
bending, while convexly designed side surfaces of
V-shaped beads prevent a complete closing of a bead.
The beads are preferably produced with a depth
of lO - 80~, preferably 20 - ~0~, of the thicXness of
the composite panel, they are usually in the range of
about 5 - 20 mm. The possible bead depth is primaxily
dependent on the elasto-plastic deformability of the
core of plastic foam, if need be with the additives
mentioned.
By variation of the spacing of the beads, their
depth, their mukual angle and/or their cross-sectional
shape, virtually any b~nding of the composite panel, in
one direction or the other, can be achieved. With
respect to the bending radius, the lower limit is set
by the rigidity or elasto-plasticity of the core
material. The elasto-plastic deformability of the core
and covering layer/layers can be utilised to an extent
which until now has not been considered possible.
Depending on the regular or irregular
application of one or more parameters, geometrically
regular or irregular bending surfaces are obtained.
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The composite rigidity is not significantly impaired,
the vapour impermeability of the plastically deformed
covering layer is fully retained.
A composite panel provided with beads can be
bent without special aids, in particular without
gauges, until the beads- are closed and thus the
predetermined bending surface produced. In one use
according to the invention, a composite panel may be
used as a structural element bent on site.
In particular in the case of concave V-shaped,
U-shaped or undercut beads, at least one projecting
object can be clamped in the beads of the composite
panel during b~nding;
- Accorcling to a first variant, suspension members
are firmly clamped, to which the domed composite
panel can be fastened, or by means of which
another object can be suspended or fastened to the
domed composite panel.
The fixing of the suspension members can be
improved by their shank introduced into the bead
being widened rearwards and/or an adhesive being
added.
- According to a second variant, equally or
unequally thic~ calibrating plates are inserted
into the beads during bending, by which a
predetermined bending surface can be achieved.
Equal calibrating plates produce a bending surface
with constant radius, increasingly thic~
calibrating plates produce a less domed bending
surface and thinner calibrating plates produce a
more domed bending surface.
The bent or domed composite panels according to
the invention have a wide range of applications, in
particular in architecture or in vehicle construction.
In building construction, cold fac,ades or decorative
fac,ades of a great varie~y of forms can be produced,
interior fittings can be distinctively styled or
furniture can be produced. In the area of underground
construction, a major application is in tunnel
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construction, where an aesthetically appealing inner
lining which Illee~s all safety requirements can be
produced. In ve~licle construction, major ~pplications
are in the area of roof design, vehicle shells and
containers.
The invention is explained in more detail with
reference to exemplary embodiments represented in the
drawing, which are also the su~iect of dependent
cla~ls. In the diagrammatic representation of the
figures:
- Fig. 1 shows a partial section through a flat
composite panel with V-shaped beads,
- Fig. 2 shows the bent composite panel according
to Fig. 1,
- Fig. 3 shows a section through a U-shaped bead,
~ Fig. 4 shows a section through a pear-shaped
bead,
- Fig. 5 shows a section through a
dovetail-shaped bead, and
- Figs. 6 to 9 show a view of composite panels
with variously arranged beads.
The composite panel 10 of an essentially
customary type represented in Fig. 1 has a core 12 of
a thermoplastic rigid foam and approximately 0.9 mm
thick covering layers 14, 16 of a ductile aluminium
alloy arranged on both sides. The upper covering layer
has, however, cross-sectionally V-shaped beads 28 with
straight side walls at regular spacings a. The beads
have a depth t, which ma~es up 50% of the overall
thicXness of the composite panel 10.
In Fig. 2, the composite panel 10 of Fig. 1 is
bent to such an extent that the V-shaped beads 28 are
just closed. By virtue of the V-shaped beads 28
arranged at uniform spacing a, with equal depth t and
equal included angle, the lower covering layer 16, the
outer surface of the bent composite panel 10, is
essentially bent in the shape of a cylindrical shell.
The rounded-off, cross-sectionally U shaped
bead 28 according to Fig. 3 contains a calibrating
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plate 30. During the bending of the composite panel,
the intermediate space between the edges 32, 34 of the
beads 28 and the calibrating plate 30 contracts. When
the edges 32, 34 bear against the calibrating plate 30,
bending is complete. Depending on the thickness of the
calibrating plate 30, the bending radius of the
composite panel is greater or smaller.
Once bending is complete, the calibrating plate
30 is drawn out from the deformed beads 2~. If need
be, the open be~d can be filled up with a filling
compound.
Inserted in the cross-sectionally pear-shaped
bead 28 according to Fig. 4 there is an eyelet 36 with
a shank 38. This shank 38 is in ~ slow-setting
adhesive 40. During the bending of the composite panel
10, the intermediate space between the edges 32, 34 and
the shank 38 of the eyelet contracts until the said
shank is clamped. Depending on the required bearing
force of the eyelet 36, ~he adhesive 40 may be omitted,
but only ii the shanX 38 can be clamped with an
appropriately firln sea~ing.
~rhe cross-sectionally dovetail-shaped bead 28
represented in Fig. S contains a hook 42 with
rearwardly widened shank 44. During bending of the
composite panel 10, the bead 28 contracts until the
edges 32, 3~ clamp the shank 44 of the hoo~. The
dovetail-shaped bead 28 and the rearwardly widened
shank 44 effectively prevent a tearing-out of the hook
44 even without adhesive.
The composite panel 10 represented in Fig. 6
has beads 28, represented by dashed lines, at regular
spacings a. The parallel running beads 28 made to the
same depth extend over the entire width o~ the
composi~e panel 10. From Fig. 6 there results a
composite panel 10, curved with regular bending radius,
such as is represented in principle in Figs. 1 and 2.
According to Fig. 7, the beads 28 have a
smaller spacing a in the central region than in the
outer region. This results in a composite panel 10
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which is bent more in the central region than on the
ou-tside.
If -the beads 28 according to Fig. 7 are made
alternatingly on the upper covering layer and the lower
covering layer, an undulatingly bent composite panel 10
is produced. The beads 28 in the upper covering layer
and the lower covering layer of the composite panel 10
preferably do not overlap, i.e. they should be offs,et
in the longitudinal direction, because otherwise no
usually desired closed bending outer surface is
obtained.
The composite panel 10 represen~ed in Fi~. 8
shows beads 28 made in groups at a regular spacing a.
The beads 28 drawn in in dashed lines are made in the
upper covering layer, the beads 28 drawn in in dotted
lines are made in the lower covering layer. There are
no beads 28 between the groups. This arrangement of
the beads 28 results in a composite panel 10 bent
essentially in the shape of a Z and having a regular
xounded-off radius.
An essentially U-shaped design (not shown) of
the composite panel could be achieved if both groups of
beads 28 were arranged in the upper covering layer or
in the lower covering layer.
Fig. 9 shows a composite panel 10 having beads
28 running at a constant angle ~. This arrangement
produces a composite panel 10 bent in the shape of a
truncated cone. The depth of the beads may be uniform
or increasing in the direction of the converging beads.
The arrangement of the beads 28 which is
represented by way of example in Figs. 6 - 9 has the
effect that, by a combination of the parameters of
spacing, angle, depth and cross-sectional shape of
beads, a great variance of bending shapes can be
achieved, without needing a gauge for each.
