Note: Descriptions are shown in the official language in which they were submitted.
CA 02419843 2003-02-25
Mo-7417
LeA 35,230
LIGHTWEIGHT CONSTRUCTIONAL ELEMENT WITH
EXTERNAL RIBBING
CROSS REFERENCE TO RELATED PATENT APPLICATION
The present patent application claims the right of priority under 35
U.S.C. ~119 (a)-(d) of German Patent Application No. 102 08 953.1, filed
February 28, 2002.
FIELD OF THE INVENTION
The invention relates to a lightweight constructional element
comprising a shell-shaped basic body, in particular of metal, having
reinforcing ribs of plastics material, in particular of thermoplastic plastics
material, which are permanently fixed to the basic body.
BACKGROUND OF THE INVENTION
Stiff, high-strength lightweight structural elements with internal
ribbing already exist in what is commonly referred to as "hybrid
technology" (generally, a technology involving the combination of metal
inserts with thermoplastic plastics material). For reasons of space
constraints, however, such structures do not meet the requirements
associated with integration of additional components and application (e.g.,
conduits for wiring and air transport, and other channels, within the interior
of the basic body).
Previously, instrument panel supports or so-called cross-car beams
or cross-members in motor vehicles have been produced from steel tubing
with various welded-on or screwed-on parts. These parts have relatively
high weight. Moreover, with these elements the above-mentioned direct
molding-on of further constructional elements to the basic body using the
injection-molding process is impossible or possible only with difficulty.
CA 02419843 2003-02-25
Mo-7417
_2_
EP 370 342 A1 discloses a lightweight constructional element
consisting of a shell-shaped profile section with internal supporting ribs
consisting of molded-on thermoplastic plastics material. Although this
constructional element may be used as a support structure, in particular in
the form of plastics-metal composite bodies, its further technical
application as a constructional element is typically limited.
It is an object of the invention to develop a lightweight
constructional element which is relatively simple to manufacture and has
good physical properties, such as high stiffness and strength. Such a
newly developed lightweight constructional element preferably consists of
one or optionally a plurality of (shell-shaped) basic bodies. It is desirable
that the basic bodies of such newly developed lightweight construction
elements must provide channels for wiring or air transport, and further
applications. ft is further desirable that such newly developed lightweight
construction elements have a level of stiffness that is at least comparable
to that of prior art structures, such as metal tube cross-car beams.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a
lightweight constructional element (100) comprising:
(a) a shell-shaped basic body or shell (1 ), e.g., fabricated from
metal, having interior (20) and exterior (23) surfaces, the
interior surfaces (23) of said basic body defining an interior
space (26); and
(b) reinforcing ribs (2a, 2b) of plastics material, preferably
thermoplastic material, which are fixedly (or permanently)
attached to the exterior surface (23) of said basic body (1 ),
wherein said reinforcing ribs are fixedly attached to the exterior surface of
said basic body by means of discrete attachment points {which may
include, for example, apertures (3a), slots (3f), beads (3b) and/or
CA 02419843 2003-02-25
Mo-7417
-3-
protrusions (3c)}, said reinforcing ribs being one of directly and indirectly
fixedly attached to the exterior surface of said basic body.
The features that characterize the present invention are pointed out
with particularity in the claims, which are annexed to and form a part of this
disclosure. These and other features of the invention, its operating
advantages and the specific objects obtained by its use will be more fully
understood from the following detailed description and accompanying
drawings in which preferred embodiments of the invention are illustrated
and described.
Unless otherwise indicated, all numbers or expressions, such as
those expressing structural dimensions, quantities of ingredients, etc. used
in the specification and claims are understood as modified in all instances
by the term "about."
As used herein and in the claims, the term "perforation" means a
hole of any size or configuration, typically present in the basic body (1 )
and
optionally the flanges (8) of the basic body, and includes, but is not limited
to, apertures and/or slots.
As used herein and in the claims, the term "aperture" means a
perforation having substantially similar cross dimensions, and includes, but
is not limited to shapes selected from substantially circular, substantially
square, and/or substantially triangular.
As used herein and in the claims, the term "slot" means a
perforation that is generally elongated in one dimension relative to the
other dimensions) of the perforation, and includes, but is not limited to,
rectangular slots and elliptical slots.
CA 02419843 2003-02-25
Mo-7417
-4-
As used herein and in the claims, and unless otherwise noted, the
term "plastics material" means thermoplastic materials (plastics materials
that are substantially free of a 3-dimenstional crosslink network) and/or
thermoset plastics materials (plastics materials having 3-dimensional
crosslink network).
As used herein and in the claims, the term "directly fixedly attached"
with regard to the exterior reinforcing plastic ribs means that the
reinforcing ribs are form- and force-closed connected to the basic body by
means of apertures or slots.
As used herein and in the claims, the term "indirectly fixedly
attached" with regard to the exterior reinforcing plastic ribs, means that the
reinforcing ribs are force-closed connected to the basic body by means of
beads or protrusions.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a representative perspective side view of a substantially
closed lightweight constructional element (103) according to the present
invention, which includes a cover plate (5a);
Figure 2 is a representative perspective side view of an open
lightweight constructional element (100) according to the present
invention, which includes substantially laterally outwardly extending (or
doubly angled) reinforcing flanges (8);
Figure 3 is a representative section through a closed profile section
of substantially closed lightweight constructional element (105) that is
similar to that of Figure 2; and
CA 02419843 2003-02-25
Mo-7417
-5-
Figure 4 is a representative section through a lightweight
constructional element (107) similar to that of Figure 3 having apertures in
the basic body and in the cover plate.
In Figures 1 through 4, like reference numerals designate the same
components.
DETAILED DESCRIPTION OF THE INVENTION
In an embodiment of the present invention, the basic body is
fabricated from a material selected from at least one of thermoset plastics
material, thermoplastic materials and metal. In a further embodiment, the
plastics material of the reinforcing ribs is selected from at least one of
thermoset plastics material and thermoplastic materials.
The connection between the reinforcing ribs and the basic body is
preferably effected at or by means of perforations (e.g., apertures and/or
slots) through which the plastics material passes and extends beyond the
plane of the perforations (e.g., apertures and/or slots).
Increased or improved stiffness of the constructional element may
be obtained in a preferred embodiment of the present invention when the
connection between the reinforcing ribs and the basic body is additionally
effected by means of at least partially encasing the rim portions of the
basic body by means of plastics material. More particularly, in an
embodiment of the present invention the basic body of the lightweight
constructional element has a shape selected from substantially U-shapes
and substantially V-shapes each having two sidewalls (e.g., substantially
opposed sidewalls), each sidewall having a rim, and the reinforcing ribs
are further fixedly attached to the exterior surface of the basic body by
means of plastic material of the ribs at least partially encasing the rims.
CA 02419843 2003-02-25
Mo-7417
-6-
In a preferred embodiment of the present invention, the lightweight
constructional element is given still greater stiffness if the basic body has
in its rim portion an angled reinforcing flange, in particular a doubly-angled
reinforcing flange. More particularly, the basic body of the lightweight
constructional element has a shape selected from substantially U-shapes
and substantially V-shapes each having two sidewalls (e.g., substantially
opposed sidewalls), each sidewall having a substantially laterally
outwardly extending flange (e.g., an angled reinforcing flange), and said
reinforcing ribs are further fixedly attached to the exterior surface of the
basic body by means of the plastic material of the ribs at least partially
encasing the flanges.
These angled rim portions (or laterally outwardly extending flanges)
of the basic body can be variously formed (e.g., in accordance with the
deep-draw process of the metal part), and their configurations are, for
example, primarily determined by the design requirements of the
constructional element as a whole.
The lightweight constructional element is particularly simple to
manufacture but also simple to detach (e.g., separate the reinforcing ribs
from the basic body or shell) for the purposes of plastics material
recycling, if the connection between the reinforcing ribs and the basic body
is effected by means of the plastics material molded onto the exterior
surfaces of the basic body, e.g., by means of the injection-molding
technique, as will be discussed in further detail herein.
In a particularly preferred embodiment, to further increase the
strength of the lightweight constructional element, the exterior surface of
the basic body ( in addition to the reinforcing ribs) is encased with plastics
material. The exterior encasing plastics material may optionally be
continuous with the plastics material of the exterior reinforcing ribs.
CA 02419843 2003-02-25
Mo-7417
-7-
Particularly advantageous with respect to corrosion protection, e.g.
of metal inserts, is a preferred lightweight constructional element of the
present invention, in which the interior surfaces of the basic body are at
least partially encased in plastics material. The interior encasing plastics
material may optionally be continuous with the plastics material of the
exterior reinforcing ribs that extends through perforations in the basic body
into the interior space of the basic body, and thereby serving to further
fixedly attach the exterior reinforcing ribs to the exterior surface of the
basic body.
The spatial form of the shell of the lightweight constructional
element can be freely selected, depending on the application. A preferred
constructional form of the lightweight constructional element is
characterized in that the the basic body has a shape is selected from
substantially U-shapes and/or substantially V-shapes (relative to the profile
section of the basic body).
The advantage of the basic body of the present invention, as
compared to closed box-section basic bodies, lies in the greater simplicity
of its manufacture, e.g., by means of the extrusion process.
To form wiring or air conduits the shell-shaped basic body may
optionally be closed with a cover plate. A lightweight constructional
element is therefore preferred which is characterized in that at least one
additional cover plate enclosing the interior space of the basic body at
least partially, and in particular completely, is attached across (or over)
the
interior space of the basic body. In an embodiment of the present
invention, the basic body has a shape selected from substantially U-
shapes and substantially V-shapes each having two sidewalls, each
sidewall having a substantially laterally outwardly extending flange, the
lightweight constructional element further includes a cover plate, which is
CA 02419843 2003-02-25
Mo-7417
_g_
fixedly attached to each of the flanges and covers at least a portion of the
interior space of the basic body.
The cover plate can project in any desired manner beyond the side
portions (or sidewalls) of the lightweight constructional element. In which
case it may then optionally contain further functional elements such as
dashboard parts, etc., and can therefore serve as a further design feature.
In a particularly preferred form of the lightweight constructional
element of the present invention, the cover plate is jointly encased by
plastics material in the rim portion of the basic body to close the interior
space. In an embodiment, the cover plate is fixedly attached to the basic
body by means of plastics material encasing each of the flanges and at
least a portion of the cover plate that abuts (or is at least superposed over)
each of said flanges.
The stiffness of the constructional element can be further increased
if the cover plate is preferably combined with the basic body by means of
apertures or slots arranged one above the other, through which the
plastics material passes and extends beyond the plane of the apertures or
slots. A kind of riveted plastics connection is thereby produced. In an
embodiment of the present invention, each of the cover plate and the
flanges have a plurality of pertorations, each perforation having a plane, at
least some of the perforations of the cover plate and flanges are aligned
with each other, the aligned perforations form a plurality of aligned
perforations each having a plane, the cover plate is fixedly attached to the
basic body by means of plastics material extending through and beyond
the plain of least some of the aligned perforations. The perforations of the
aligned perforations may be selected from apertures andlor slots.
If an airtight channel is required, the connection between the
closure plate and the shell-shaped basic body or the lightweight
CA 02419843 2003-02-25
Mo-7417
_g_
constructional element may be effected by means of a welded or bonded
joint, and/or an additional sealing element such as a rubber seal may be
inserted.
For certain applications (e.g., air conduit, etc.) a preferred
lightweight constructional element is advantageous which is characterised
in that the attachment point of the cover plate to the basic body is closed in
an airtight manner by means of a welded or bonded joint or by means of a
sealing agent, in particular a rubber seal. The cover plate, in an
embodiment of the present invention, forms an airtight seal over the
interior space of the basic body by means of a welded joint, a bonded joint
and/or a sealing agent positioned between each of the flanges and at least
a portion of the cover plate that is fixedly attached to each of the flanges.
A preferred form of the lightweight constructional element in which
the interior of the basic body has at least one dividing wall, in particular
of
thermoplastic plastics material, has proved successful in separately
accommodating a plurality of conduits.
Sheet metal, preferably steel or aluminum sheet, diecast metal, in
particular aluminum, zinc or magnesium, or fiber-reinforced plastics
material or composite material may be used as the preferred material for
the basic body and optionally the cover plate of the lightweight
constructional element.
As a preferred material for the reinforcing ribs and optionally the
encasement of the lightweight constructional element, a plastics material
selected from the series: polycarbonate, polyester, in particular PET or
PBT, polyurethane, polystyrene, polyamide, polyalkylene, in particular
polypropylene, is used.
CA 02419843 2003-02-25
Mo-7417
-10-
Lightweight, structural and housing elements with high functionality
find application in the vehicle industry, in mechanical engineering and the
appliances industry, in the electrical industry and in other constructional
elements.
In particular, these elements can be used in the vehicle industry as
instrument panel supports or so-called cross-car beams (CCBs).
If applicable, further constructional elements such as trim or
functional parts for the dashboard area can be directly molded on to the
exterior areas of the basic body or the ribbing, using the injection-molding
process.
Manufacture of the above-mentioned lightweight structural elements
is possible in a reasonable manner with a relatively short production time,
especially using the injection-molding process. In a preferred embodiment
of the present invention discrete attachment points include a plurality of
perforations, a plurality of beads and/or a plurality of protrusions. The
reinforcing ribs are preferably fixedly attached to the outer surface of the
basic body by means of a process of molding plastics material onto the
exterior surface of the basic body, the molded-on plastics material at least
one of: (i) extends through at least some of the perforations and into the
interior space of the basic body; (ii) fills at least some of the slots; (iii)
fills
at least some of the beads; and (iv) encases at least partially at least some
of the protrusions. The process of molding plastics material onto the
exterior surface of the basic body includes: (i) injection-molding (in the
case of thermoplastic materials): (ii) reaction-injection-molding (in the
case of thermoset plastics materials, such as 2-pack thermoset or
thermosetable polyurethane compositions); and (iii) a combination of
injection-molding and reaction-injection-molding (in the case of plastics
compositions that include both thermoplastic materials and thermoset
plastic materials or components).
CA 02419843 2003-02-25
Mo-7417
-11-
The invention therefore further relates to the application of a
lightweight constructional element according to the invention as a
structural component or support structure for motor vehicle or aircraft
construction, in particular as a support structure with a channel for wiring
or gas, particularly preferably with an air channel, and particularly
preferably as an instrument panel support or crass-car beam. Articles of
manufacture that may include the lightweight constructional element of the
present invention include, but are not limited to: a structural component of
a motor vehicle; a structural component of an aircraft; and a structural
component having a channel for receiving at least one of a cable and a
gas. Further articles of manufacture that may include the lightweight
constructional element of the present invention include, but are not limited
to: an instrument panel support; and a cross-car beam.
In a particularly preferred embodiment of the present invention, the
reinforcing ribs, of the lightweight constructional element, form a
continuous unitary structure on the exterior surface of the basic body.
The invention is described in further detail below, in an exemplary
manner, with reference to the drawing figures.
EXAMPLES
Example 1
A U-shaped profile section (basic body or shell) 1 of sheet steel
(thickness 0.8 mm) with angled flanges 8 (in the rim region 29) is provided
on its exterior with cruciform ribs 2a of thermoplastic plastics material
(e.g.,
of glass-fiber reinforced PA 6). The ribbing is molded on to the profile
section using the injection-molding process, as described previously
herein. Disposed across the interior of the profile section 1 is a cover 5a
which is permanently fixed to the rim 8 of the profile section 1 by means of
a molded rim encasement 4.
CA 02419843 2003-02-25
Mo-7417
-12-
At certain points of its surface the profile section 1 has perforations
in the form of apertures 3 through which the thermoplastic material
passes. The plastics material here forms a riveted connection 3a similar
to that depicted in Figure 3. The profile section 1 according to Figure 1
forms part of a heated air conduit.
Example 2
Figure 2 represents a profile section 1, similar to that of Example 1,
in which the profile section 1 has doubly-angled reinforcing flanges 8. Here
the lateral reinforcing ribs 2b are disposed perpendicularly with respect to
the extension and flanges of the profile section.
The ribs 2b are attached at profile section slots 3f by means of
thermoplastic material passing through the profile section 1. Here the
profile section is formed as an open box section.
Example 3
In the metal profile section 1 shown in Figure 3 the internal surfaces
20 are encased by thermoplastic plastics material 9, which can be seen in
cross-section. Similarly to that depicted in Figure 1, the profile section 1
has a cover plate 5a which is attached to the profile section 1 by means of
bonding agent 6.
In place of the bonding agent 6, attachment by a welded edge joint
can also be provided (not shown). In case of a welded joint the same
material/plastics material may be used for the cover plate as for the
adjoining interior encasement.
The cover plate 5a is manufactured, in this case, from glass-fiber
reinforced thermoset material.
CA 02419843 2003-02-25
Mo-7417
-13-
Three variants of attachment points are shown in cross-section in
Figure 3: a simple aperture 3a, a trapezoidal bead 3b, and a hemi-
spherical protrusion 3c.
The profile section 1 has doubly-angled flanges 8 which are
encased in thermoplastic plastics material 4 and, in combination with the
attachment points 3a, 3b, 3c, ensure the strength of the composite.
For further stiffening of the constructional element the cover plates
5a may have reinforcing beads 7 disposed in a longitudinal, transverse or
cruciform manner.
Example 4
In Figure 4 a metal profile 1 is shown in cross-section, which has
external plastic ribbing 2a, 2b, similarly to the profile section according to
Example 2. Here again, through the injection-molding process, the
thermoplastic material passes through the profile section basic body 1 at
the apertures 3a, 3e or the slots 3f and forms attachment points.
Attached across the interior of the profile section 1 is a metal cover
5b which is seated directly on the metal profile 1 and forms therewith an
electrically shielded channel 26. Apertures 3g in the cover 5b are
disposed directly above the apertures 3e or slots 3f in the profile section 1
and are riveted by means of the plastics material to the profile section 1.
In view of the angled flange portion of the basic body in Figure 3,
only longitudinal ribs 2b of plastics material on the side areas of the basic
body, according to the direction of deformation, are consequently now
possible as reinforcement.
The profile section also has over its entire exterior surface 23 an
outer encasement 10 of the same thermoplastic material as the ribs 2a,
CA 02419843 2003-02-25
Mo-7417
-14-
2b. In this case the attachment points 3d, 3e, 3f do not need to be located
directly in the area of the ribs 2a, 2b.
The process of attaching a metal cover plate 5b may be executed
directly by the normal injection-molding process of the lightweight
constructional element or using the so-called "in-mold-assembly-process",
instead of a conventional joining process (bonding, welding 6).
Although the invention has been described in detail in the foregoing
for the purpose of illustration, it is to be understood that such detail is
solely
for that purpose and that variations can be made therein by those skilled in
the art without departing from the spirit and scope of the invention except as
it may be limited by the claims.
