LIGHTWEIGHT PANELLING AND A METHOD OF MANUFACTURING SAME

PANNEAU ALLEGE; METHODE DE FABRICATION

English Abstract

Abstract of the DISCLOSURE
In lightweight panelling, at least one core layer (10) is
provided, to the outer surfaces (11,12) of which thin outer
layers (15, 16) are attached. A plurality of parallel slits
(17) of predetermined width are provided which extend from
one intact outer layer (16) through a substantial part of
the thickness of the core layer (10), in order to make the
panelling easily deformable in one direction.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Panelling of lightweight construction comprising a
lightweight core layer and two relatively thinner outer
layers joined respectively to two outer surfaces defined by
the core layer, and wherein the core layer defines a
plurality of parallel slits, each of a predetermined width
and extending from an intact said outer layer through at
least a substantial part of the thickness of said core
layer.
2. Panelling as claimed in Claim 1, wherein said core
layer comprises a honeycomb material with the cell axis of
the honeycombs perpendicular to said outer surfaces.
3. Panelling as claimed in Claim 2, wherein said core
layer comprises Nomex and paper.
4. Panelling as claimed in Claim 1, wherein covering
layers are attached to said outer surfaces of the core
layer between the core layer and the outer layers.
5. Panelling as claimed in Claim 4, wherein said covering
layers comprising preimpregnated web material.
6. Panelling as claimed in Claim 1, wherein the depth of
the slits is in the range corresponding to 80% to 95% of
the thickness of the core layer.
7. Panelling as claimed in Claim 1, wherein the slits
are equidistant from one another.
8. A method of manufacturing lightweight panelling having
a lightweight core layer and comprising the steps of
(a) applying first and second covering layers to first
and second opposite surfaces of said core layer

respectively;
(b) forming a plurality of slits, each of a
predetermined width, completely through said first covering
layer and through a substantial part of the thickness of
said core layer (10); and
(c) finishing the panelling on at least the side of
said first covering layer by the application thereto of a
first outer layer.
9. A method as claimed in Claim 8, comprising the further
step of
(d) applying a second outer layer to said second
covering layer.
10. A method as claimed in Claim 8, wherein said first and
second covering layers are bonded to the core layer in a
press under the action of heat.
11. A method as claimed in Claim 8, wherein said first and
second covering layers comprise preimprednated web
material.
12. A method as claimed in Claim 8, wherein said outer
layer is attached to said underlying covering layer by an
adhesive.
13. A method as claimed in Claim 8, wherein said slits
are formed by machining.
14. A method as claimed in Claim 13, wherein said slits
are formed by sawing or milling.
15. A method as claimed in Claim 8, wherein in step (a) a
tear-off web is applied to the first covering layer and
immediately prior to step (c) said tear-off web is removed
to leave the surface defined by the first covering layer in

a suitable condition for attachment by adhesive of said
first outer layer.
16. A method as claimed in Claim 8, wherein the blank
formed in step (a) is fixed to a manipulable support plate
for the duration of the subsequent steps of the method.
17. A method as claimed in Claim 9, wherein the steps (a)
and (d) are carried out simultaneously.

Description

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LIG~T~EIGHT PANELLING AND A METHOD OF MANUFACTURING SAME
The present invention relates to panelling of
lightweight construction and .to a ~ethod of manufacturing
such panelling.
Known lightweight panelling is usually of sandwich
construction and compri~es a core layer of foamed
artificial resin, balsa wood or honeycomb material, plus
outer layers to ~tiffen it. Preferably, the panelling is
constructed with a core layer of honeycomb structure, su~h
as is described in, for example, International Patent
Application W0 ~9/10258.
In many applications, for example in the ~anufacture
of a sliding door, it is advantageous for the panelling to
be highly resilient or flexible in a first bending
direction and simultaneously extremely rigid in a ~econd
direction perpendicular to the first. The known panelling
mentioned above cannot fulfill this requirement.
The object of the present invention iq to provide
lightweight panelling with ~ predetermined degree of
flexi~ility in one direction, which differ3 ~ubstantially
from the degree of flexibility in a 3econd perpendicular
direction.
According to a first a~pect of the present invent;on
there is provided panelling o~ lightweight con~truction
comprising a lightweight core layer and two relatively

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thinner outer layers joined respectively to two outer
surface~ defined by the core layer, and wherein the core
layer defines a plurality of parallel slits, each of a
predetermined width and extending from an intact said outer
layer through at least a substantial part of the thickness
of said core layer.
According to a second aspect of the present invention
there iq provided a method of manufacturing lightweight
panelling having a lightweight core layer and comprising
the steps of
(a) applying first and second covering layers to first
and second opposite surfaces of said core layer
respectively;
(b) forming a plurality of slits, earh of a
predetermined width, completely through said first covering
layer and through a substantial part of the thickness of
said core layer (10); and
(c) finishing the panelling on at least the side of
said first covering layer by the application thereto of a
first outer layer.
lt will be appreciated that the first outer layer
coverQ the outer openings of the ~lits and, on the one
hand, endows the remaining core ~aterial with the required
stiffness, while on the other hand, can be compressed in
the places where it covers the slits to allow the panelling
to flex toward said outer layer. On the ~pposite surface,
however, the outer layer and the remaining core material
attached to it are incomprecsible and provide a ~mooth
surface that is merely bent.
Preferably, covering layers are attached to ~aid outer
surfaces of the core layer between the core layer and the
outer layer~. ,

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Fig~. 1 to 5 show ~chematically various stage in the
manufacture of one embodiment of lightweight panelling in
accordance with the invention.
In the embodiment of the invention shown in the
drawings, a core layer 10 comprising a honeycomb material
with the cell axis of the honeycombs perpendicular to Raid
outer surfaces 11, 12 is made from, for example, Nomex and
paper. First and second covering layers 13, 14, which
preferably comprise a web material preimpregnated with
phenol, epoxy or thermoplastic material, are laid onto the
outer Rurfaces 11 and 12 of the core layer 10. Onto the
first covering layer 13 a tear-off web 18 iQ also laid and
to the lower covering layer 14 is attached, ~y adhesive
between the two layers, a superficial or outer layer 15
such as an adhesive sheet. This adhe~ive sheet 15
constitutes the outer surface of the finished structure and
hence is preferably decorated or ornamented (colored,
textured etc.) as the user desires.
The tear-off web 18 and the first outer layer 15 are
each covered with a separating sheet 19, so that the stack
80 produced can be pressed between surfaces 20, 20~ of a
heatable press, as shown in Fig. 1. During ~ompression and
simultaneous heating in the pre~s, the covering layers 13
and 14 bond to the underlying core layer 10 a~d the fir~t
outer layer 1~ bonds to the second covering layer 14.
After the bonds between the layers have hardened, the
resulting laminated structure is laid on a support plate 21
with the ~irst outer ,la~er 15 face down, as shown in Fig.
2. This facilit~tes manipulation of the "blank". First,

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the tear-off web 18 is removed, leaving a roughened surface
on the first covering layer 13.
Next, a saw or an end mill is used to make a series of
parallel slits 17 in the ~lank in such a way that a
residual part of the thickness of the core layer 10 is
retained, as shown in Fig. 3. In principle, it is also
possible to extend the slits 17 all the way to the second
covering layer 14 but care must be taken that the remaining
material is sufficiently rigid to resist forces applied in
a direction parallel to the surface whilst still being
capable of bending elastically. Preferably, the depth of
the slits is in the range corresponding to 80% to 95% of
the thickness of the core layer and the slits are
e~uidistant from one another,
After the slits 17 have been made, the resulting
structure, together with the support plate 21, is again
placed between the compression surfaces 20, 20' of the
heatable press, as shown in Fig. 4. The support plate 21
is prevented from sticking to the surface 20' by the
interposition of a separating sheet 19 therebetween.
Prior to compression of the structure by the surface
20, an adhesive layer 22 is applied to the roughened
surface of the first covering layer 13. On the adhesive
layer is laid a second ~uperficial or outer layer 16, which
in turn is separated from the associated compression
surface 20 by a second separation ~heet 19. During the
subsequent compression and heating process the ~econd outer
layer 16 bonds to the underlying first covering layer 13.
The panelling so produced is now removed fro~ the support
plate 21 and has a structure, in cross-section, as shown in
Fig. 5.
It should be note~ at this juncture that, for clarity,

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the relative thickne~ses of the layerR 13-16 are greatly
exaggerated in the drawings.