U.S. patent application number 11/331071 was filed with the patent office on 2006-06-01 for reinforced impact beam with layered matrix.
This patent application is currently assigned to N.V. BEKAERT S.A.. Invention is credited to Paul Corscadden, Willem Dekeyser, Peter A.M. Van Damme.
Application Number | 20060112560 11/331071 |
Document ID | / |
Family ID | 27741220 |
Filed Date | 2006-06-01 |
United States Patent
Application |
20060112560 |
Kind Code |
A1 |
Van Damme; Peter A.M. ; et
al. |
June 1, 2006 |
Reinforced impact beam with layered matrix
Abstract
An impact beam having a polymer matrix and a metal reinforcing
structure, the metal reinforcing structure including metal cords
that can be made from metal elements having a diameter of 100 .mu.m
or more. The polymer matrix can include a thermoplastic material
and/or a fiber material, and the metal can be steel, and the metal
cords can be parallel to each other. The polymer matrix can include
two or more layers that can be made from the same or different
material, one of which can be positioned around the surface of the
metal cords and can have a mechanical bond with the cord. The
invention also includes a method of making the impact beam.
Inventors: |
Van Damme; Peter A.M.; (AA
Bergen op Zoom, NL) ; Corscadden; Paul; (Winsford,
GB) ; Dekeyser; Willem; (Assebroek, BE) |
Correspondence
Address: |
FOLEY AND LARDNER LLP;SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
N.V. BEKAERT S.A.
POLYNORM N.V.
|
Family ID: |
27741220 |
Appl. No.: |
11/331071 |
Filed: |
January 13, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10927130 |
Aug 27, 2004 |
7007990 |
|
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11331071 |
Jan 13, 2006 |
|
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|
10383259 |
Mar 7, 2003 |
6883843 |
|
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10927130 |
Aug 27, 2004 |
|
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Current U.S.
Class: |
29/897.2 ;
29/527.1; 29/527.3 |
Current CPC
Class: |
Y10T 29/49622 20150115;
B29K 2995/0089 20130101; B29L 2031/3044 20130101; Y10T 29/49984
20150115; B60R 2019/1806 20130101; B60R 19/18 20130101; B60R
2019/1853 20130101; B29C 70/46 20130101; B29C 70/52 20130101; Y10T
29/4998 20150115; B29C 70/885 20130101 |
Class at
Publication: |
029/897.2 ;
029/527.1; 029/527.3 |
International
Class: |
B21B 1/46 20060101
B21B001/46; B21D 53/88 20060101 B21D053/88 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 8, 2002 |
EP |
02 100 236.5 |
Claims
1. A method for providing an impact beam, comprising the steps of:
providing a polymer matrix sheet; providing metal cords and/or
metal cord tapes comprising metal cords; heating the polymer matrix
sheet; bringing the metal cords and/or metal cord tapes and polymer
matrix sheet together and providing the metal cords and/or metal
cord tapes and polymer matrix sheet to a mold; molding the metal
cords and/or metal cord tapes and polymer matrix sheet to thereby
provide an impact beam for impact reinforcement; and causing and/or
allowing the impact beam to cool.
2. The method of claim 1, wherein the polymer matrix sheet
comprises glass fibers.
3. A method for providing an impact beam, comprising the steps of:
providing metal cords and/or metal cord tapes comprising metal
cords; extruding polymer material and providing extruded polymer
material to the metal cords and/or metal cord tapes; molding the
metal cords and/or metal cord tapes and polymer material to thereby
provide an impact beam for impact reinforcement; and causing and/or
allowing the impact beam to cool.
4. A method for providing an impact beam, comprising the steps of:
providing fiber strands and/or reinforcing fabrics; providing metal
cords and/or metal cord tapes comprising metal cords; providing
uncured or not fully cured polymer material to the fiber strands
and/or the reinforcing fabrics and the metal cords and/or metal
cord tapes by drawing the fiber strands and/or the reinforcing
fabrics and the metal cords and/or metal cord tapes through a bath
of uncured or not fully cured polymer material; curing the fiber
strands and/or the reinforcing fabrics and the metal cords and/or
metal cord tapes and the uncured or not fully cured polymer
material by drawing the fiber strands and/or the reinforcing
fabrics and the metal cords and/or metal cord tapes and the uncured
or not fully cured polymer material through a heated pultrusion die
to thereby provide a pultruded article; and cutting the pultruded
article to lengths to thereby provide an impact beam for impact
reinforcement.
5. A method of providing an impact beam, comprising the steps of:
providing metal cords and/or metal cord tapes comprising metal
cords; bringing the metal cords and/or metal cord tapes in an
extrusion mold and positioning the metal cords and/or metal cord
tapes in the mold; providing polymer material in the extrusion mold
to provide an impact beam for impact reinforcement; and causing
and/or allowing the impact beam to cool.
6. The method of claim 5, further comprising the steps of providing
glass fibers and positioning the glass fibers in the extrusion
mold.
7. The method of claim 3, wherein the polymer material includes
glass fibers.
8. The method of claim 1, wherein the metal cord tapes comprise
metal cords and a polymer matrix around the metal cords.
9. The method of claim 3, wherein the metal cord tapes comprise
metal cords and a polymer matrix around the metal cords.
10. The method of claim 4, wherein the metal cord tapes comprise
metal cords and a polymer matrix around the metal cords.
11. The method of claim 5, wherein the metal cord tapes comprise
metal cords and a polymer matrix around the metal cords.
12. The method of claim 1, further comprising the step of heating
the metal cords and/or metal cords tapes.
13. Use of the impact beam of claim 1 for support of bumpers of
vehicles and/or to improve impact resistance of a vehicle's
coachwork.
14. Use of the impact beam of claim 3 for support of bumpers of
vehicles and/or to improve impact resistance of a vehicle's
coachwork.
15. Use of the impact beam of claim 4 for support of bumpers of
vehicles and/or to improve impact resistance of a vehicle's
coachwork.
16. Use of the impact beam of claim 5 for support of bumpers of
vehicles and/or to improve impact resistance of a vehicle's
coachwork
Description
[0001] The present application is a divisional of U.S. application
Ser. No. 10/927,130, filed Aug. 27, 2004, which is a divisional of
U.S. application Ser. No. 10/383,259, filed Mar. 7, 2003, the
entire contents of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to impact beams and
reinforcements, and a method to provide such impact beam. The
invention further relates to the use of an impact beam for support
of bumpers of vehicles or for impact reinforcing of parts of
vehicles.
BACKGROUND OF THE INVENTION
[0003] Presently known composite impact beams comprise a polymer
matrix, reinforced with glass fibers or other polymer fibers. An
impact beam may also comprise metal parts, usually on the places
where the impact beam receives compression load during impact. U.S.
Pat. No. 5,290,079 gives an example of such impact beam. In U.S.
Pat. No. 5,290,079 the impact beam also comprises a woven wire
mesh, which is to improve the ductility and flexibility of the
impact beam.
[0004] Presently known composite impact beams in general have the
disadvantage that they tend to break or in two parts at the
location of impact, or into several small particles which are
projected towards objects which are in the periphery of the impact
beam. This may cause further damage to these objects.
SUMMARY OF THE INVENTION
[0005] It is an object of the present invention to provide an
improved impact beam having increased resistance to impact. it is
also an object of the invention to provide an impact beam having a
high-energy absorption. It is an other object of the invention to
provide an impact beam having an improved integrity during and
after impact.
[0006] An impact beam as subject of the invention comprises a
polymer matrix and a metal reinforcing structure. According to the
present invention, the metal reinforcing structure comprises one or
more metal cords.
[0007] Preferably, the metal reinforcing structure comprises two or
more metal cords, the metal cord being preferably essentially
parallel to each other.
[0008] The wording "essentially parallel" is to be understood in a
sense that for each pair of metal cords, said cords being present
one next to the other, for each point of an axis of a first of
these metal cords, a related point of the axis of the second metal
cord can be defined, which point is the crossing point of the axis
of the second metal cord, with the plane through the point of the
axis of the first metal cord and being perpendicular to the
direction of the axis of the first metal cord at this point. The
difference in direction of the axis's of the metal cords, in each
pair of points is less than 25.degree., e.g. less than 15.degree.
or even less than 10.degree., such as less than 5.degree..
[0009] An impact beam is characterized by a direction in which
impact forces are expected to work on the impact beam. This
direction is hereafter referred to as `impact direction`. Impact
beams are characterized by an impact plane, being the plane
perpendicular to the direction of impact. One dimension of this
plane is usually relatively large and is hereafter referred to as
length of the impact beam. The second dimension of the impact beam
in this impact plane, is usually much smaller than the length. This
direction is hereafter referred to as height of the impact beam.
The dimension of the impact beam, perpendicular to impact plane is
referred to as thickness of the impact beam.
[0010] The metal cord of an impact beam as subject of the invention
may be provided in a direction essentially parallel to the length
of the impact beam.
[0011] Most preferably however, the metal cords are provided with a
curved shape during molding of the impact beam as subject of the
invention. The curves have a bending radius in the plane
perpendicular to the plane defined by the length and height, and
parallel to the length of the impact beam. The curvature preferably
extends to the side of the impact beam on which the impact force is
to be expected to work.
[0012] The metal cord preferably used for an impact beam as subject
of the invention, are of a type which can absorb relatively high
amounts of impact energy but also other metal cords may be
used.
[0013] Examples here are: [0014] multi-strand metal cords e.g. of
the m.times.n type, i.e. metal cords, comprising m strands with
each n wires, such as 4.times.7.times.0.10 or 3.times.3'0.18; the
last number is the diameter of each wire, expressed in mm. [0015]
compact cords, e.g. of the 1.times.n type, i.e. metal cords
comprising n metal wires, n being greater than 8, twisted in only
one direction with one single step to a compact cross-section, such
as 1.times.9.times.0.18 or 1.times.12.times.0.18; the last number
is the diameter of each wire, expressed in mm. [0016] layered metal
cords e.g. of the l+m (+n) type, i.e. metal cords with a core of l
wires, surrounded by a layer of m wires, and possibly also
surrounded by another layer of n wires, such as 2+4.times.0.18; the
last number is the diameter of each wire, expressed in mm. [0017]
single strand metal cords e.g. of the 1.times.m type, i.e. metal
cords comprising m metal wires, m ranging from two to six, twisted
in one single step, such as 1.times.4.times.0.25; the last number
is the diameter of each wire, expressed in mm. [0018] Open metal
cords e.g. of the m+n type, i.e. metal cords with m parallel metal
wires surrounded by n metal wires, such as disclosed in U.S. Pat.
No. 4,408,444, e.g. a metal cord 2+2.times.0.25; the last number is
the diameter of each wire, expressed in mm.
[0019] All cords as described above can be equipped with one or
more spiral wrapped wires to increase the mechanical bond of the
cords in the polymer matrix, and/or to bundle the n single parallel
crimped or non-crimped but plastically deformed wires if the cord
is provided using such parallel wires.
[0020] Preferably however, the metal cord used in the context of
the present invention may be a metal cord with a high elongation at
fracture, i.e. an elongation exceeding 4%, e.g. an elongation
between 5% and 10%. High elongation metal cord has more capacity to
absorb energy.
[0021] Such a metal cord is: [0022] either a high-elongation or
elongation metal cord (HE-cords), i.e. a multi-strand or single
strand metal cord with a high degree of twisting (in case of
multi-strand metal cords: the direction of twisting in the strand
is equal to the direction of twisting of the strands in the cord:
SS or ZZ, this is the so-called Lang's Lay) in order to obtain an
elastic cord with the required degree of springy potential; an
example is a 3.times.7'30.22 High Elongation metal cord with lay
lengths 4.5 mm and 8 mm in SS direction; [0023] or a metal cord
which has been subjected to a stress-relieving treatment such as
disclosed in EP-A1-0 790 349; an example is a
2.times.0.33+6.times.0.33 SS cord. [0024] as an alternative or in
addition to a high elongation metal cord, the metal cord may be
composed of one or more wires which have been plastically deformed
so that they are wavy. This wavy nature additionally increases the
elongation. An example of a wavy pattern is a helix or a spatial
crimp such as disclosed in WO-A1-99/28547.
[0025] According to the required properties of the impact beam as
subject of the invention, all metal cords may be identical, or
alternatively, different metal cords may be used to provide the
impact beam.
[0026] The metal elements used to provide these metal cords may
have a diameter, being a diameter of a radial cross section of the
metal elements, which is equal or larger than 100 .mu.m, more
preferred larger than 125 .mu.m e.g. more than 150 .mu.m or even
more than 175 .mu.m. All metal elements of a metal cord may have
the same diameter, or the diameters of the metal elements may
differ from each other.
[0027] Preferably, the optical diameter of the metal cord is larger
than 200 .mu.m, or even larger than 250 .mu.m, such as larger than
300 .mu.m or more. The optical diameter of the metal cord is to be
understood as the diameter of the smallest imaginary circle,
encompassing the radial cross section of the metal cord.
[0028] Most preferably steel cords are used to provide the impact
beam as subject of the invention. Presently known steel alloys may
be used to provide the steel cords. Preferably, the steel cords are
subjected to a stress relieving thermal treatment, e.g. by passing
the steel cord through a high-frequency or mid-frequency induction
coil of a length that is adapted to the speed of the steel cord
during production. It was observed that, increasing the temperature
to more than 400.degree. C. for a certain period of time, a
decrease in tensile strength of the steel cord (a reduction of
approximately 10%), but at the same time, an increase of the
plastic elongation of the cord before rupture of more than 6% may
be obtained. Such steel cords are hereafter referred to as stress
relieved steel cords.
[0029] An impact beam as subject of the invention comprises an
elastomeric, thermoset or thermoplastic polymer matrix.
[0030] The polymer matrix may comprise polymer material, being a
thermoplastic or thermoplastic elastomer polymer material. More
preferred, the polymer material is selected from the group
consisting of polypropylene, polyethylene, polyamide, polyethylene
terephtalate, polybutylene terephtalate, polycarbonate,
polyphenylene oxide as well as blends of these materials, or
thermoplastic elastomers, e.g. polyamide- or polyolefin-based
thermoplastic elastomers such as polyesteramides,
polyetheresteramides, polycarbonate-esteramides or
polyether-block-amides.
[0031] Alternatively, the polymer material may be a thermoset
polymer material, preferably selected from the group consisting of
unsaturated polyesters, epoxies, vinyl-esters and phenolic
resins.
[0032] The polymer matrix may further comprise glass- or C-fibers,
polymeric fibers and/or mineral fillers to reinforce the polymer
matrix. Fibers can either be random, unidirectional, woven;
stitched, chopped, or a combination of those.
[0033] The polymer matrix may have two layers. The first layer,
hereafter referred to as `embedding layer` makes contact to the
metal cord surfaces. Such embedding layer may be extruded around
the metal cord, or several metal cords may be bundles and provided
with an embedding layer coating. Alternatively, several metal cords
are laminated in one plane between two foils of polymer material,
providing a tape-like structure, hereafter generally referred to as
`metal cord tape`, or steel cord tapes in case the metal cord tape
is provided using steel cords.
[0034] Around this metal cord with embedding layer, a second layer,
hereafter referred to as volume layer, may be provided, e.g. by
extrusion or in a molding process.
[0035] Preferably the polymer material of the embedding layer is an
thermoplastic elastomeric or thermoplastic material, preferably a
thermoplastic polymer material, more preferred being selected from
the group consisting of polypropylene, polyethylene, polyamide,
polyethylene terephtalate, polybutylene terephtalate,
polycarbonate, polyphenylene oxide as well as blends of these
materials, or thermoplastic elastomers, e.g. polyamide- or
polyolefin-based thermoplastic elastomers such as polyesteramides,
polyetheresteramides, polycarbonate-esteramides or
polyether-block-amides. Alternatively, the polymer material may be
a thermoset polymer material, preferably selected from the group
consisting of unsaturated polyesters, epoxies, vinyl-esters and
phenolic resins.
[0036] The polymer material of the volume layer is a thermoplastic
elastomeric, thermoset or thermoplastic material, preferably a
thermoplastic polymer material, more preferred being selected from
the group consisting of polypropylene, polyethylene, polyamide,
polyethylene terephtalate, polybutylene terephtalate,
polycarbonate, polyphenylene oxide as well as blends of these
materials, or thermoplastic elastomers, e.g. polyamide- or
polyolefin-based thermoplastic elastomers such as polyesteramides,
polyetheresteramides, polycarbonate-esteramides or
polyether-block-amides. Alternatively, the polymer material may be
a thermoset polymer material, preferably selected from the group
consisting of unsaturated polyesters, epoxies, vinyl-esters and
phenolic resins.
[0037] This volume layer may further comprise glass- or C-fibers,
polymeric fibers and/or mineral fillers to reinforce the volume
layer. Fibers can either be random, unidirectional, woven;
stitched, chopped, or a combination of those.
[0038] In order to assure a good adhesion between the metal cords
and the polymer material, an adhesion promoter can be applied on
the metal cords.
[0039] Possible adhesion promoters are bifunctional coupling agents
such as silane compounds. One functional group of these coupling
agents is responsible for the binding with the metal or metal
oxides; the other functional group reacts with the polymer. More
details about these coupling agents can be found in the PCT
application WO-A-99/20682.
[0040] In order to improve the impact resistance to the required
level, the amount of metal cord per section of the impact beam as
subject of the invention in a direction defined by the height and
thickness of the impact beam, may be chosen.
[0041] Best results are obtained when the metal cords are arranged
in one or more planes, parallel to each other and to the impact
plane of the impact beam, or one or more planes parallel to each
other and being provided with a curved shape during molding of the
impact beam. The curvature preferably extends to the side of the
impact beam on which the impact force is to be expected to work.
Each plane may be provided by means of a metal cord tape or steel
cord tape, having embedding layers which may be equal or different
from each other. Each plane may comprise metal or steel cords,
being equal or different from each other.
[0042] An impact beam as subject of the invention may be
manufactured using different production techniques.
[0043] A method for providing an impact beam, comprises the steps
of [0044] providing a polymer matrix sheet; [0045] providing metal
cords and/or metal cord tapes; [0046] heating the polymer matrix
sheet; [0047] bringing the metal cords and/or metal cord tapes and
polymer matrix sheet together and providing the metal cords and
polymer matrix sheet to a mold; [0048] molding the metal cords
and/or metal cord tapes and polymer matrix sheet, providing an
impact beam; [0049] cooling the impact beam.
[0050] Alternatively, a method for providing an impact beam,
comprises the steps of [0051] providing metal cords and/or metal
cord tapes; [0052] extruding polymer material and providing
extruded polymer material to the metal cords and/or metal cord
tapes; [0053] molding the metal cords and/or metal cord tapes and
polymer matrix sheet, providing an impact beam; [0054] cooling the
impact beam.
[0055] As another alternative, a method for providing an impact
beam, comprises the steps of [0056] providing fiber strands and/or
reinforcing fabrics; [0057] providing metal cords and/or metal cord
tapes, [0058] providing uncured or not fully cured polymer material
to said fiber strands and/or reinforcing fabrics and metal cords
and/or metal cord tapes by drawing the fiber strands and/or the
reinforcing fabrics and the metal cords and/or metal cord tapes,
through a bath of uncured or not fully cured polymer material;
[0059] curing the fiber strands and/or the reinforcing fabrics and
the metal cords and/or metal cord tapes and the uncured or not
fully cured polymer material by drawing the fiber strands and/or
the reinforcing fabrics and the metal cords and/or metal cord tapes
and the uncured or not fully cured material through a heated
pultrusion die, so providing a pultruded article; [0060] cutting
pultruded article to lengths, so providing an impact beam.
[0061] As even an other alternative, a method for providing an
impact beam, comprises the steps of [0062] providing metal cords
and/or metal cord tapes; [0063] bringing the metal cords and/or
metal cord tapes in an extrusion mold and position the metal cords
and/or metal cord tapes in the mold; [0064] providing polymer
material in the extrusion mold to provide an impact beam; [0065]
cooling the impact beam.
[0066] Preferably, a polymer matrix sheet, most preferably a Glass
Mat Reinforced Thermoplastic Prepreg is used. The prepreg can
either contain random, unidirectional, woven, stitched or chopped
fibers from glass or other materials or combinations of these.
Similarly, long fiber thermoplastic compounds can be used
comprising chopped strand glass fibers or fibers from other
materials This thermoplastic prepreg is heated during a
prepreg-heating step, using any kind of oven system until the
thermoplastic resin melts. In case of long fiber thermoplastic
compound, an extruder is used to melt the long fiber thermoplastic
compound.
[0067] After the polymer heating step and possibly a metal cord
and/or metal cord tape heating step, the metal cords or metal cord
tape and the polymer material are brought together, usually by
providing the polymer material e.g. glass mat reinforced
thermoplastic prepreg around the metal cord or metal cord tape, and
provided to a compression molding tool. The metal cord or metal
cord tape and polymer material together are subjected to a molding
step. The metal cord or metal cord tape is positioned in the
location of the section of the profile where it is intended to be
located to obtain the maximum performance. During the closing of
the mold, the polymer material flows and encapsulates the metal
cord or metal cord tape. Possibly, the metal cords or the metal
cord tape is provided with a curved shape.
[0068] After the mold is closed, the mold and molded material is
cooled during a cooling step. The mold is re-opened. An impact beam
as subject of the invention is so provided.
[0069] The same molding process can be used, but the oven is
replaced by an extruder which produces blobs of polymer material,
e.g. hot lofted glass-filled thermoplastics or long fiber
thermoplastic compound that are then manipulated into the tool or
mold, together with the metal cord or metal cord tape. After
molding, the molded material is cooled.
[0070] Alternatively, glass and/or other fiber strands and metal
cords or metal cord tape may be subjected to a pultrusion process
in order to provide an impact beam as subject of the invention.
First fiber strands and/or reinforcing fabrics and metal cords or
metal cord tape are provided. Uncured or not fully cured polymer
material is provided to these fiber strands and/or reinforcing
fabrics and metal cords or metal cord tape by drawing them through
a bath of uncured or not fully cured material. Then the fiber
strands and/or reinforcing fabrics and cords and the polymeric
polymer material are drawn through a heated pultrusion die in case
of a thermoset material or through a cooling die in case of
thermoplastic material. A pultruded article is so provided. The
pultruded article is cut into lengthsEach cut length is than an
impact beam as subject of the invention. In a second step the
impact may be bend or shaped to the desired end shape.
[0071] Alternatively, glass and/or other fiber strands and metal
cords or metal cord tape may be subjected to an over-extrusion
process in order to provide an impact beam as subject of the
invention. Metal cords or metal cord tapes are provided and brought
in an extrusion mold and position in the mold. Polymer material,
e.g. thermoplastic material is provided in the extrusion mold, e.g.
by extrusion. After cooling, the mold comprises now an impact beam.
Possibly, the polymer material comprises glass fibers, next to the
polymer material, which is or fully, or partially or not cured.
[0072] The impact beam as subject of the invention may further
comprise openings for fixings or mounting other objects. These
openings can be brought into the impact beam by punching, drilling,
CNC, laser cutting or similar techniques, but also by means of
inmold punching.
[0073] Preferably, although not always necessarily, the metal cords
or metal cord tapes may also be heated during a metal cord heating
step, using any kind of oven or by induction heating.
[0074] Best impact resistance is obtained when the metal cords are
embedded in the polymer matrix, having either one or more layers,
in such a way that they have a limited freedom to elongate and/or
untwist during impact.
[0075] Depending on the type of the metal cord construction, a
relatively large amount of impact energy may be absorbed depending
on the impact absorption mechanism, which is typical for that metal
cord construction.
[0076] High elongation (HE-) cords can absorb impact energy by the
structural deformation of the cords due to movements of strands one
to another in the cord. When structurally deformed filaments are
used to provide the metal cords, also the removing of the
structural deformation out of the filaments during elongation of
the metal cord will cause an absorption of the impact energy. In
case the metal cord is a stress relieved steel cord, also the
plastic deformation of the filaments will provide an absorption of
impact energy.
[0077] The polymer matrix is preferably bound to the metal cord by
means of a mechanical bond. The polymer matrix may or may not be
bound to the metal cords by means of a chemical bond. During a
local impact, the polymer matrix, eventually by means of an
embedding layer and a volume layer, distribute the local force over
the full cord length. This results in a full use of the cord's
energy absorption abilities hence the energy to be absorbed by
other parts outside the beam is reduced and local breakage of the
polymer matrix is postponed. The energy absorption of the cord is
either through plastic stretching of the cord itself, through
torsional deformation of the cord such as untwisting, or energy
dissipation in the interface between cord and polymer layer due to
friction when a relative movement of cord versus matrix is taking
place. If the impact force is such that the local stresses in the
polymer matrix exceed its breaking strength the polymer matrix will
fall apart into pieces which still adhere to the metal cords. This
falling apart will absorb a limited amount of impact energy, but
after this falling apart, the metal cords may elongate to a larger
extent and will be able to absorb to a large extent all impact
energy possible until they break.
[0078] Alternatively, when a polymer matrix comprising an embedding
layer and a volume layer, this volume layer preferably will fall
apart first by impact. The pieces adhere to the embedding layer and
allow the embedding layer and the metal cords to extend to some
extent. Then possibly the embedding layer will fall apart but will
adhere to the metal cords. These metal cords can then elongate and
absorb the impact energy, which is still left.
[0079] When in an impact beam several metal cord tapes are used,
all parallel to each other, the bond between two metal cord tapes
may be broken. Impact energy may then be absorbed due to the
friction caused by the relative movement of both metal cord tapes
relatively to each other.
[0080] An impact beam as subject of the invention may be used to
support soft bumpers of vehicles such as cars, busses or trucks. It
may also be used to improve the impact resistance of other elements
of the vehicle's coachwork to impact forces. Impact beam as subject
of the invention may be used to make e.g. doors, frame, bonnet or
hood and or cross beams more impact resistant. A person skilled in
the art understands that the shape of cross sections of an impact
beam as subject of the invention, as well as the outer shape of the
impact beam, may be adjusted to the use of the impact beam.
[0081] The impact beam as subject of the invention absorbs the
impact energy and protects the other elements of the vehicle for
damaging. The impact beam as subject of the invention also prevents
the particles of the polymer matrix to damage peripheral elements
of the vehicle, since the integrity of the impact beam after impact
can be secured.
BRIEF DESCRIPTION OF THE DRAWINGS
[0082] The invention will now be described into more detail with
reference to the accompanying drawings wherein (See drawings
below)
[0083] FIG. 1a being schematically a view of a cross section of an
impact beam as subject of the invention
[0084] FIG. 1b being schematically a front view of an impact beam
as subject of the invention.
[0085] FIG. 2, FIG. 3, FIG. 4a and FIG. 4b being schematically a
view of a cross section of an alternative impact beam as subject of
the invention.
[0086] FIGS. 5a to 5c being a scheme of a method to provide an
impact beam as subject of the invention.
[0087] FIG. 6 shows schematically the use of an impact beam as
subject of the invention to support a vehicle bumper.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
[0088] An impact beam as subject of the invention is schematically
shown in FIG. 1a and FIG. 1b.
[0089] An impact beam 100 has a length 11, which is substantially
larger than the height 12 and the thickness 13 of the impact beam
100. The embodiment as shown in FIG. 1 has a thickness that is
provided by a pair of legs 14 and a main volume 15. The legs 14 may
be used to fix the impact beam to other parts of the object to
which it is to be mounted, whereas the main volume 15 (with its
thickness 16) will absorb most of the impact energy provided by an
impact in direction as indicated with arrow 19.
[0090] The main volume 15 and the legs 14 comprise a polymer
matrix. In the main volume 15, metal cords 18 are present in a
direction essentially parallel to the length 11 of the impact beam
100. Preferably all metal cord are present in one or more planes
10. The metal cords 18 used to provide the metal cord tape were
7.times.7 cords. Such cords comprise a core strand of a filament of
0.21 mm, round which 6 filaments of 0.19 mm are twisted. Around
this core strand, 6 strands are twisted, each strand comprising a
core filament of 0.19 mm around which 6 filaments of 0.175 mm are
twisted.
[0091] The matrix is a glass fiber filled polypropylene.
[0092] Alternative embodiments are shown in FIG. 2, FIG. 3 and
FIGS. 4a and 4b.
[0093] An impact beam is shown in FIG. 2, according to an
embodiment of the present invention. The impact beam 100 has a
polymer matrix 24 that includes two layers: a first layer, or
embedding layer, 20 and a second layer, or volume layer, 21. The
matrix 24 may be arranged so that the matrix 24 is formed around
metal cords 18.
[0094] The metal cord are provided by means of a metal cord tape 23
which is provided in a plane essentially perpendicular to the
impact direction 19.
[0095] The metal cords used to provide the metal cord tape were
7.times.7 cords. Such cords comprise a core strand of a filament of
0.21 mm, round which 6 filaments of 0.19 mm are twisted. Around
this core strand, 6 strands are twisted, each strand comprising a
core filament of 0.19 mm around which 6 filaments of 0.175 mm are
twisted.
[0096] Type polymer material of the embedding layer 20 was a
polyolefin based thermoplastic elastomer.
[0097] Type polymer material of volume layer 21 is a glass fiber
filled polypropylene.
[0098] FIG. 3 shows another alternative embodiment of an impact
beam as subject of the invention. The metal cords 18 are provided
by means of two metal cord tapes 31 and 32, which are provided
parallel to each other and essentially parallel to the impact
direction 19.
[0099] FIG. 4a shows an improved impact beam as subject of the
invention where the legs 41 and main volume 42 are connected to
each other by means of a transition zone 43. Several metal cord
tapes 44 and possible individual metal cords 45 may be used to
provide impact resistance in both the main volume 42 or the
transition zone 43.
[0100] FIG. 4b shows an other alternative impact beam as subject of
the invention. Several metal cord tapes 44 and possible individual
metal cords 45 may be used to provide impact resistance in both the
main volume 42 or the legs 41.
[0101] Turning now to a method to provide an impact beam as subject
of the invention, such method is schematically shown in FIGS.
5a-5c.
[0102] First a glass mat reinforced thermoplastic prepreg 500 is
provided comprising polymer matrix 501 and possibly glass fiber mat
502 (step 50). Also metal cords 503 are provided preferably having
an adhesion layer 504 around the surface of the metal cords 503.
Most preferably the metal cord and adhesion layer are provided as a
metal cord tape 505. (step 51).
[0103] As shown in step 52 of FIG. 5a, the glass mat reinforced
thermoplastic prepreg 500 is heated to soften the polymer material
501 using a furnace 506. Glass mat reinforced thermoplastic prepreg
may be supported and transported through the furnace using a
transporting means e.g. a belt 507. After being heated, the hot
glass mat reinforced thermoplastic prepreg is taken of the
transporting means as indicated with arrow 508, and is provided for
addition to the metal cord tape in step 54.
[0104] As shown in step 53 of FIG. 5a, the metal cord tape 505 may
be heated to soften the polymer material 504 using a furnace 509.
Metal cord tape may be supported and transported through the
furnace using a transporting means e.g. a belt 510. Possibly after
being heated, the metal cord tape is taken off the transporting
means as indicated with arrow 508 and is provided for addition to
the metal cord tape in step 54. A skilled man understands that in
case the metal cord or metal cord tape is not to be heated, they
may be provided to step 54 with no handling as in step 53.
[0105] In step 54, the metal cords or metal cord tape 505 and the
hot glass mat reinforced thermoplastic prepreg 500 are brought
together, e.g. by adding or stacking the different layers one on
top of the other.
[0106] The stack 511, comprising the glass mat reinforced
thermoplastic prepreg 500 and the metal cord or metal cord tape 505
are provided to a mold comprising two parts, being the female mold
512 and the male mold 513 (step 55a). The molds 512 and 513 are
closed (step 55b) and the stack 511 is bend and shaped to the open
area inside the closed mold.
[0107] After this molding (step 55a and 55b) the mold and the
shaped impact beam is cooled to a temperature for which the polymer
material 501 is solidified (cooling step 56). The impact beam may
then be taken out of the molds and is ready for further processing,
such as quality control or provision of additional openings.
[0108] An impact beam as subject of the invention is so provided,
which may be used as support for soft bumpers of vehicles, as shown
in FIG. 6.
[0109] An impact beam 61 is connected to peripheral elements 62 of
the vehicle caochwork. A soft bumper element 63 may be provided
covering the impact beam 61. when the vehicle strikes an object, an
impact force with a direction 64 will apply in as indicated in FIG.
6.
[0110] The metal cord present in the impact beam 61 will adsorb the
impact energy to a large extent, and the polymer material of the
impact beam will adhere to the metal cord to a large extent. This
to avoid that particles of the polymer material will be projected
further towards the parts of the vehicle which are located behind
the impact beam.
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