U.S. patent application number 09/969909 was filed with the patent office on 2002-05-09 for internal reinforcement for hollow structural elements..
Invention is credited to Wycech, Joseph S..
Application Number | 20020053179 09/969909 |
Document ID | / |
Family ID | 46276561 |
Filed Date | 2002-05-09 |
United States Patent
Application |
20020053179 |
Kind Code |
A1 |
Wycech, Joseph S. |
May 9, 2002 |
Internal reinforcement for hollow structural elements.
Abstract
A reinforced beam has an internal I-beam structure with opposed
adhesive foam layers. The foam layers are extruded, cut to length
and placed on opposed surfaces of the I-beam. When the reinforced
beam is heated. The adhesive layers expand to secure the I-beam in
place.
Inventors: |
Wycech, Joseph S.; (Grosse
Pointe Shores, MI) |
Correspondence
Address: |
HENKEL CORPORATION
2500 RENAISSANCE BLVD
STE 200
GULPH MILLS
PA
19406
US
|
Family ID: |
46276561 |
Appl. No.: |
09/969909 |
Filed: |
October 3, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09969909 |
Oct 3, 2001 |
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09440746 |
Nov 16, 1999 |
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09440746 |
Nov 16, 1999 |
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08914481 |
Aug 19, 1997 |
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6058673 |
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08914481 |
Aug 19, 1997 |
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08644389 |
May 10, 1996 |
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Current U.S.
Class: |
52/834 |
Current CPC
Class: |
B62D 29/002 20130101;
E06B 3/222 20130101; E06B 2003/226 20130101; B29C 44/18 20130101;
E04C 3/29 20130101 |
Class at
Publication: |
52/721.4 ;
52/721.2 |
International
Class: |
E04C 003/34 |
Claims
What is claimed is:
1. A reinforced structural member, comprising: a structural member
having a plurality of walls with a channel shaped inner surface
formed by said walls to define a space, a reinforcing beam disposed
in said space, said reinforcing beam being of differing shape than
the shape of said channel shaped inner surface, said reinforcing
beam being non-uniformly spaced from said channel shaped inner
surface, said reinforcing beam having two opposed plates, each of
said plates having a principal surface, said plates being separated
from each other, said plates being interconnected by an
interconnecting structural spacing element, a first expanded
structural foam adhesive body disposed on one of said principal
surfaces and a second expanded structural foam adhesive body
disposed on the other of said principal surfaces spaced from and
distinct said first adhesive body said first expanded structural
foam adhesive body being bonded to one of said walls of said
structural member and said second expanded structural foam adhesive
body being bonded to another of said walls of said structural
member for reinforcing said structural member, open spaces in said
structural member between said inner surface and said reinforcing
beam, said reinforcing beam being a pair of mated back to back
C-shaped channels, each of said channels having a central web and
an offset extension extending outwardly away from said central web,
said central webs of said C-shaped channels being disposed against
each other to form said interconnecting structural spacing element,
and said offset extensions comprising said plates.
2. The reinforced structural member recited in claim 1, wherein
portions of at least one of said plates is non-coplanar with other
portions of said at least one of said plates.
3. The reinforced structural member recited in claim 1, wherein
said first and said second adhesive bodies are the sole connection
of said beam to said structural member.
4. The reinforced structural member recited in claim 1, wherein
said plates are planar and parallel to each other.
5. The reinforced structural member recited in claim 1, wherein
said structural member is made of metal.
6. The reinforced structural member recited in claim 1, wherein
said first and said second adhesive bodies are thermally
expandable.
7. The reinforced structural member recited in claim 1, wherein
said principal surfaces of said reinforcing beam are co-extensive
with said reinforcing beam.
8. The reinforced structural member recited in claim 1, wherein
said first and second adhesive bodies cover substantially the
entirety of said principal surfaces.
9. The reinforced structural member recited in claim 1, wherein
said adhesive bodies comprise planar ribbons of thermally expanded
adhesive.
10. The reinforced structural member recited in claim 1, wherein
said reinforcing beam is roll formed metal.
11. The reinforced structural member recited in claim 1, wherein at
least one of said principal surfaces is discontinuous such that a
longitudinal space is formed therein.
12. The reinforced structural member recited in claim 1, wherein
said reinforcing beam is extruded aluminum.
13. The reinforced structural member recited in claim 1, wherein
said adhesive bodies are limited to said principal surfaces.
14. The reinforced structural member recited in claim 1, wherein
said adhesive bodies include a two part air-cured adhesive.
15. The reinforced structural member recited in claim 1, wherein
said adhesive bodies are one part adhesive.
16. The reinforced structural member recited in claim 1, wherein
said beam is glass filled nylon.
17. The reinforced structural member recited in claim 1, wherein
said beam is a cast cement-based material.
18. The reinforced structural member recited in claim 1, wherein
said structural member is bent along its length, and said
reinforcing beam being bent along its length to match the geometry
of said structural member.
19. The reinforced structural member recited in claim 1, wherein
said reinforcing beam is totally enclosed within said structural
member.
20. The reinforced structural member recited in claim 19, wherein
said structural member comprises a U-shaped vehicle rail section,
and one of said walls of said structural member being a plate over
said U-shape.
21. A reinforced structural member, comprising: a structural member
having a plurality of walls with a channel shaped inner surface
formed by said walls to define a space, a reinforcing beam disposed
in said space, said reinforcing beam being of differing shape than
the shape of said channel shaped inner surface, said reinforcing
beam being non-uniformly spaced from said channel shaped inner
surface, said reinforcing beam having two opposed plates, each of
said plates having a principal surface, said plates being separated
from each other, said plates being interconnected by an
interconnecting structural spacing element, each of said principal
surfaces terminating in an outer edge located outwardly of said
interconnecting structural spacing element, a first expanded
structural foam adhesive body disposed on one of said principal
surfaces and a second expanded structural foam adhesive body
disposed on the other of said principal surfaces spaced from and
distinct from said first adhesive body, said first expanded
structural foam adhesive body being bonded to one of said walls of
said structural member and said second expanded structural foam
adhesive body being bonded to another of said walls of said
structural member for reinforcing said structural member, open
spaces in said structural member between said inner surface and
said reinforcing beam, said structural member being bent along its
length, and said reinforcing beam being bent along its length to
match the geometry of said structural member.
22. An insert for reinforcing a hollow structural member,
comprising: a reinforcing beam having two opposed plates, each of
said plates having a principal surface, said plates being separated
from each other, said plates being interconnected by an
interconnecting structural spacing element, each of said principal
surfaces terminating in an outer edge located outwardly of said
interconnecting structural spacing element, a first expandable
adhesive body disposed on one of said principal surfaces, a second
expandable adhesive body disposed on the other of said principal
surfaces spaced from said first adhesive body, said reinforcing
beam being a pair of mated back to back C-shaped channels, each of
said channels having a central web and an offset extension
extending outwardly away from said central web, said central webs
of said C-shaped channels being disposed against each other to form
said interconnecting structural spacing element, and said offset
extensions comprising said plates.
23. The insert recited in claim 22, wherein portions of at least
one of said plates is non-coplanar with other portions of said at
least one of said plates.
24. The insert recited in claim 22, wherein said plates are planar
and parallel to each other.
25. The insert recited in claim 22, wherein said first and said
second adhesive bodies are thermally expandable.
26. The insert recited in claim 22, wherein said first and second
adhesive bodies cover substantially the entirety of said principal
surfaces.
27. The insert recited in claim 22, wherein said adhesive bodies
comprise planar ribbons of thermally expanded adhesive.
28. The insert recited in claim 22, wherein said reinforcing beam
is roll formed metal.
29. The insert recited in claim 22, wherein said reinforcing beam
is extruded aluminum.
30. The insert recited in claim 22, wherein said adhesive bodies
are limited to said principal surfaces.
31. The insert recited in claim 22, wherein said adhesive bodies
include a two part air-cured adhesive.
32. The insert recited in claim 22, wherein said adhesive bodies
are one part adhesive.
33. The insert recited in claim 22, wherein said beam is glass
filled nylon.
34. The insert recited in claim 22, wherein said beam is a cast
cement-based material.
35. The insert recited in claim 22, wherein said reinforcing beam
is of generally I shape.
36. The insert recited in claim 22, wherein said reinforcing beam
is bent along its length.
37. A reinforced structural member, comprising: a structural member
having a plurality of walls with a channel shaped inner surface
formed by said walls to define a space, a reinforcing beam disposed
in said space, said reinforcing beam being of differing shape than
the shape of said channel shaped inner surface, said reinforcing
beam being non-uniformly spaced from said channel shaped inner
surface, said reinforcing beam having two opposed plates, each of
said plates having a principal surface, said plates being separated
from each other, said plates being interconnected by an
interconnecting structural spacing element, each of said principal
surfaces terminating in an outer edge located outwardly of said
interconnecting structural spacing element, a first expanded
structural foam adhesive body disposed on one of said principal
surfaces and a second expanded structural foam adhesive body
disposed on the other of said principal surfaces spaced from and
distinct from said first adhesive body, said first expanded
structural foam adhesive body being bonded to one of said walls of
said structural member and said second expanded structural foam
adhesive body being bonded to an other of said walls of said
structural member for reinforcing said structural member, open
spaces in said structural member between said inner surface and
said reinforcing beam, and at least one C-shape being formed by
said spacing element and at least a portion of each of said plates.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a division of application Ser. No.
09/440,746, filed Nov. 16, 1999, which is a continuation in part of
application Ser. No 08/914,481, filed Aug. 19, 1997, now U.S. Pat.
No. 6,058,673 which is a continuation of application Ser. No.
08/644,389 filed May 10, 1996.
TECHNICAL FIELD
[0002] The present invention relates generally to reinforced
structures for use in motor vehicles and, more specifically,
relates to lightweight structures for reinforcing hollow structural
elements.
BACKGROUND OF THE INVENTION
[0003] In a number of applications in the automotive industry,
high-strength structural members with low mass are required.
Various composite materials have been proposed in the past as
structural members such as exotic light-weight alloys. In most
applications, however, mass reduction must not be at the expense of
strength and must be balanced against the cost of the product to
the consumer. Thus there is a need for maintaining or more
preferably for increasing the strength of structural members
without significantly increasing materials and labor costs.
[0004] The reinforcement of motor vehicle structural members
through the use of composite materials is also known. For example
the present inventor has disclosed a number of metal/plastic
composite structures for use in reinforcing motor vehicles
components. In U.S. Pat. No. 4,901,500 entitled "Lightweight
Composite Beam" a reinforcing beam for a vehicle door is disclosed
which comprises an open channel-shaped metal member having a
longitudinal cavity which is filled with a thermoset or
thermoplastic resin-based material. In U.S. Pat. No. 4,908,930
entitled "Method of Making a Torsion Bar" a hollow torsion bar
reinforced by a mixture of resin with filler is described. The tube
is cut to length and charged with a resin-based material.
[0005] In U.S. Pat. No. 4,751,249 entitled "Reinforcement Insert
for a Structural Member with Method of Making and Using the Same" a
precast reinforcement insert for structural members is provided
which is formed of a plurality of pellets containing a thermoset
resin with a blowing agent. The precast member is expanded and
cured in place in the structural member. In U.S. Pat. No.
4,978,562, entitled "Composite Tubular Door Beam Reinforced with a
Syntactic Foam Core Localized at the Mid Span of the Tube" a
composite door beam is described which has a resin-based core that
occupies not more than one-third of the bore of a metal tube.
[0006] In U.S. Pat. No. 4,019,301 entitled "Corrosion-Resistant
Encasement For Structural Members" a piling or other structure is
disclosed in which an I-beam is encased in a housing into which a
resin is poured.
[0007] In U.S. Pat. No. 5,575,526 entitled "Composite Laminate Beam
for Automotive Body Construction," a hollow laminate beam
characterized by high stiffness-to-mass ratio and having an outer
portion which is separated from an inner tube by a thin layer of
structural foam is described. In U.S. Pat. No. 5,755,486 entitled
"Composite Structural Reinforcement Member," a W-shaped carrier
insert reinforcement which carries a foam body is described for use
in reinforcing a hollow beam.
[0008] In addition a number of metal laminates constructions are
known in which that metal plates are bonded together by an
intervening layer of resin. It is also known to form a metal
laminate sheet for use as a floor panel member which comprises a
pair of flat metal sheets having an intervening layer of asphalt or
elastic polymer.
[0009] Although filling the entirety of a section with plastic foam
does significantly increase section stiffness (at least when
high-density foams are utilized), they also increase mass and thus
part weight which, as stated is an undesirable feature in
automotive applications. Moreover, although increasing the metal
gauge of a section or adding localized metal reinforcements will
increase stiffness, as the metal thickness increases, it is more
difficult to form the part due to limitations of metal forming
machines. Importantly, in many applications increasing metal gauge
will not work effectively because mass and stiffness are increased
proportionately, with no resultant change in the dynamic stiffness
frequency of the part.
[0010] Finally, filling a section entirely with foam may be
prohibitively expensive, creates a large heat sink and requires
elaborate sealing operations to close access holes in the
stampings.
[0011] Accordingly, it would be desirable to provide a low-cost
technique for reinforcing a hollow structural member without
proportionately increasing the mass. The present invention provides
sections which have increased strength with only moderate increases
in mass and without the use of high volumes of expensive resins. In
many applications, the present invention reduces vibrations which
cause unwanted `shake` of a component which is primarily subjected
to bending rather than torsion.
SUMMARY OF THE INVENTION
[0012] In one aspect the present invention provides a reinforced
structural member for automotive applications. The reinforced
structure is a hollow beam such as a rail section or the like
having a pair of opposed inner surfaces. The hollow beam is
reinforced through the use of a specially formed insert. The insert
is a beam (preferably linear) having two opposed plates which
substantially span the width of the cavity defined by the walls of
the hollow structural member. The opposed plates preferably have
generally planar surfaces. A layer of thermally expandable foam
with adhesive properties is bonded to each of these planar
surfaces. The insert is placed in the cavity of the hollow
structural member such that the adhesive layers are adjacent the
opposed inner surfaces of the hollow beam. The beam with the
reinforcing insert is then heated to thermally activate the
expandable adhesive layers. As the adhesive layers expand they bond
securely to the inner surfaces of the hollow beam to form an
integral structure, i.e. a structurally reinforced beam.
[0013] In one aspect the reinforcing insert of the present
invention is wholly enclosed in the hollow structural member. In
that aspect the insert is dropped into an open channel which is
then closed with a top plate.
[0014] In one aspect the reinforcing insert of the present
invention is an I-beam which is formed of metal, glass filled nylon
or a cementitious material that contains microspheres.
[0015] Thus, in accordance with the present invention there is
provided in one aspect a reinforced structural member, comprising a
structural member defining a space, the structural member having
two opposed walls; a reinforcing beam disposed in the space, the
reinforcing beam having two opposed plates, each of the plates
having a principal surface the plates being separated by a
predetermined distance with the principal surfaces being
approximately parallel to one another and the plates being
interconnected by an interconnecting structural spacing element; a
first thermally expanded adhesive body disposed on one of the
principal surfaces and a second thermally expanded adhesive body
disposed on another of the principal surfaces; and the first
thermally expanded adhesive body being bonded to one of the walls
of the structural member and the second thermally expanded adhesive
body being bonded to another of the walls of the structural
members.
[0016] These and other advantages and objects of the present
invention will now be more fully described with reference to the
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a cross section of a reinforced beam in accordance
with the present invention in which the reinforcing insert has an
I-beam configuration;
[0018] FIG. 2 is a perspective view of the reinforced beam of FIG.
1 with the top plate removed to reveal the insert beam;
[0019] FIG. 3 is a cross section of a reinforced beam in accordance
with the present invention in which the reinforcing insert has an
I-beam configuration wherein the I-beam is constructed of two
mating sections;
[0020] FIG. 4 is a cross section of a reinforced beam in accordance
with the present invention in which the reinforcing insert has a
partial double web configuration;
[0021] FIG. 5 is a cross section of a reinforced beam in accordance
with the present invention in which the reinforcing insert has a
full double web configuration;
[0022] FIG. 6 is a cross section of a reinforced beam in accordance
with the present invention in which the reinforcing insert has an
I-beam configuration constructed as a dual fold structure; and
[0023] FIG. 7 a cross section of a reinforced beam in accordance
with the present invention in which the reinforcing inset has an I
beam configuration wherein the I-beam is a cast cementitious
structure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE
INVENTION
[0024] Referring now to FIG. 1 of the drawings reinforced beam 20
is shown generally having hollow beam or structure 22 which will
typically be a metal stamping for example a rail section of a motor
vehicle frame. Accordingly, hollow beam 22 comprises a linear
channel section 24 having metal top plate 26. For the purposes of
this description hollow beam 22 will be referred to as having top
surface or area 30 and bottom surface or area 32, but it is to be
understood that the references to top and bottom are arbitrary and
will depend on the geometry and orientation of the finished
assembly. Top plate will generally be attached to section 24 at
flanges 34 by spot welding or the like.
[0025] The advantages of the present invention are achieved through
the use of a specialized reinforcement member which comprises
reinforcing insert in this case I-beam 36 having a pair of opposed
plates or spaced carrier members 38 and 40 which are connected by a
spanning or spacer portion, web 42. Each plate has an associated
principal surface shown here as principal surfaces 44 and 46. On
each principal surface 44 and 46 a layer of thermally expanded
adhesive foam 48 and 50 is disposed which functions both as a means
for securing I-beam 36 in place and as a vibration dampening
element. Although I-beam 36 may be straight, in many applications
it may have various bends and slopes to match the geometry of the
part which is being reinforced. The I-beam 36 may or may not be
corrosion resistant depending on its end use.
[0026] A number of resin-based compositions can be utilized to form
adhesive foam layers 48 and 50 in the present invention. The
preferred compositions impart excellent strength stiffness, and
vibration dampening characteristics to beam 20 while adding only
marginally to the weight. With specific reference now to the
composition of adhesive foam layers 48 and 50, the density of the
material should preferably be from about 20 pounds per cubic feet
to about 40 pounds per cubic feet to minimize weight. The melting
point, heat distortion temperature and the temperature at which
chemical breakdown occurs must also be sufficiently high such that
layers 48 and 50 substantially maintain their structure at high
temperatures typically encountered in paint ovens and the like.
Therefore adhesive foam layers 48 and 50 layers should be able to
withstand temperatures in excess of 400 degrees F. and preferably
350 degrees F. for short times. Also, adhesive foam layers 48 and
50 should be able to withstand heats of about 130 degrees F. to 210
degrees F. for extended periods without exhibiting substantial
heat-induced distortion or degradation.
[0027] In more detail, in one particularly preferred embodiment
adhesive foam layers 48 and 50 includes a synthetic resin, a
cell-forming agent and a filler. A synthetic resin comprises from
about 50% to about 80% by weight preferably from about 55 percent
to about 70 percent by weight, and most preferably from about 55
percent to about 65 percent by weight of the material from which
adhesive layers 48 and 50 are formed. As used herein, the term
"cell-forming agent" refers generally to agents which produce
bubbles, pores, or cavities in layers 48 and 50. That is, layers 48
and 50 have a cellular structure, having numerous cells disposed
throughout their mass. This cellular structure provides a
low-density, high-strength material, which in reinforced beam 20,
provides a strong, yet lightweight structure. Cell-forming agents
which are compatible with the present invention include reinforcing
hollow microspheres or microbubbles which may be formed of either
glass or plastic. Plastic microspheres may be either thermosetting
or thermoplastic and either expanded or unexpanded. In one
embodiment, unexpanded microspheres are used which are then
expanded to form adhesive foam layers 48 and 50. The preferred
microspheres are from about 10 to about 400 and preferably from
about 40 to about 100 microns in diameter. The cell-forming agent
may also comprise a larger, lightweight material such as
macrospheres of greater than 400 microns in diameter. Also the
cell-forming agent may comprise a blowing agent which may be either
a chemical blowing agent or a physical blowing agent. Glass
microspheres are particularly preferred. Where the cell-forming
agent comprises microspheres it constitutes from about 10 percent
to about 40 percent by weight, preferably from about 15 percent to
about 40 percent by weight and most preferably from about 25
percent to about 40 percent by weight of the material which forms
layers 48 and 50. Where the cell-forming agent comprises a blowing
agent, it constitutes from about 1 percent to about 10 percent by
weight, preferably from about 1 percent to about 8 percent by
weight, and most preferably from about 1 percent to about 5 percent
by weight of layers 48 and 50. Suitable fillers include glass or
plastic microspheres, silica fume, calcium carbonate, milled glass
fiber, and chopped glass strand. Glass microspheres are
particularly preferred. Other materials may be suitable. A filler
comprises from about 10 percent to about 50 percent by weight,
preferably from about 15 percent to about 45 percent by weight and
most preferably from about 20 percent to about 40 percent by weight
of layers 48 and 50.
[0028] Preferred synthetic resins for use in the present invention
include thermosets such as epoxy resins, vinyl ester resins,
thermoset polyester resins, and urethane resins. It is not intended
that the scope of the present invention be limited by molecular
weight of the resin and suitable weights will be understood by
those skilled in the art based on the present disclosure. Where the
resin component of the liquid filler material is a thermoset resin,
various accelerators, such as 2 ethyl 4 methyl imidazole, and
benzyldimethylamine, and curing agents, preferably organic curing
agents such as dicyandiamide and low concentrations of amines or
imidizoles may also be included to enhance the cure rate. A
functional amount of accelerator is typically from about 5 percent
to about 3 percent of the resin weight with corresponding reduction
in one of the three components resin, cell-forming agent or filler.
Similarly the amount of curing agent used is typically from about 1
percent to about 8 percent of the resin weight with a corresponding
reduction in one of the three components, resin, cell-forming agent
or filler. Effective amounts of processing aids, stabilizers,
colorants, UV absorbers and the like may also be included in layer.
Thermoplastics and chemically cured adhesives may be suitable.
[0029] In the following tables, preferred formulations for adhesive
foam layers 48 and 50. It has been found that these formulations
provide a layers 48 and 50 which result in a reinforced beam 20
having excellent structural properties. All percentages in the
present disclosure are percent by weight unless otherwise
specifically designated.
1 PERCENTAGE INGREDIENT BY WEIGHT FORMULA I PEP 6134 68.5 EMI-24
1.2 Fumed Silica 4.0 DI-CY 4.3 Celogen OT 0.8 B38 22.2 FORMULA II
PEP 6134 60.5 DI-CY 4.8 DMP3O 1.2 Celogen AZ 1.5 B38 32.0
[0030] Referring again to FIGS. 1 and 2 of the drawings, foam
layers 48 and 50 preferably cover substantially the entirety of
principal surfaces 44 and 46, for example at least 80% thereof and
most preferable are limited to principal surfaces 44 and 46 i.e. in
the most preferred embodiment layers 48 and 50 do not extend beyond
the edges of principal surfaces 48 and 50. In some applications,
however, it may be desirable to cover less than 80% of principal
surfaces 44 and 46 with foam layers 48 and 50 or to extend them
beyond the edges of principal surfaces 48 and 50. As shown in FIGS.
1 and 2, I-beam 36 is a unitary structure which may be roll formed
steel or which may comprise extruded aluminum, or in one preferred
embodiment, glass filled nylon. Other materials may be suitable in
a given application. Although it is not intended to limit the full
scope of the resent invention by any specific dimensions, the
thickness of the walls of I beam 36 will typically be from about
0.8 to about 1.0 mm. The length of interconnecting web 42 will
typically be about 1 in. to about 1 ft., and the width of principal
surfaces 44 and 46 will each be about 5 in. to about 10 ft. The
length of I-beam 36 will typically be from about 6 in to about 10
ft. The thickness of each layer 48 and 50 is preferably from about
3 to about 6 mm as fully expanded. This represents an expansion of
the material as reinforced beam 20 is heated of about 50 to about
100 percent by volume. It is preferred that the edges of plates 38
and 40 be spaced apart from the inner sidewalls of section 24 by
about 5 to about 8 mm.
[0031] Adhesive layers 48 and 50 are most preferably pre-formed as
ribbons or sheets by extrusion of the preferred resin-based mixture
through an appropriate die. The ribbon is then cut to length such
that pieces are formed that fit on principal surfaces 44 and 48.
The pre-cut strips have sufficient tack to adhere well to principal
surfaces 44 and 46 so that an additional adhesive is generally not
necessary.
[0032] Referring now to FIG. 3 of the drawings, I-beam 36' is shown
as comprising to separated squared C shaped channel pieces 52 and
54. Channel pieces 52 and 54 may be extruded aluminum, glass tilled
nylon or stamped or roll formed steel. Channel pieces 52 and 54 may
be attached together as shown in the drawing by a number methods
for example spot welding or the like. Other than the two-piece
construction of I-beam 36', the reinforced beam of FIG. 3 is
essentially identical to the structure described in connection with
FIGS. 1 and 2 and accordingly, like reference numerals designate
like parts.
[0033] Referring now to FIG. 4 of the drawings I-beam 36" is shown
which includes double web portion 56 that defines double web
channel 58 at space 60 of plate 40. I-beam 36" is preferably formed
of extruded aluminum or glass filled nylon. In some applications it
may be desirable to construct I-beam 36" with two double web
potions, i.e. one in association with each plate 38,40. Again,
other than the geometry of I-beam 36", the reinforced beam of FIG.
3 is made in accordance with the description provided for FIGS. 1
and 2 herein.
[0034] FIG. 4 may be considered as illustrating the I-beam 36" to
be in the form of a spanning member having a central leg to which
continuous plate or carrier member 38 is integrally mounted. The
spanning member also has two offset legs each of which supports a
segment of the plate or carrier member 40 so that the resultant
carrier member 40 is of interrupted structure. The adhesive layer
50 may be confined to each plate segment 40 and upon activation the
adhesive would span across the plate segments when becoming
intimately bonded to bottom area 32 of the structural member 40.
Alternatively if the adhesive layer 50 has sufficient shape
retaining properties, the layer 50 may be applied to each plate
segment and also span across the space between the segments before
activation.
[0035] In FIG. 5 webs 62 and 64 form a web pair in double web
reinforcing insert 66. Double web insert 66 is preferably formed of
extruded aluminum or glass filled nvion. Webs 62 and 64 preferable
extend the entire length of double web reinforcing insert 66. In
FIG. 6 of the drawings still another configuration of the present
invention is shown in which folded reinforcing insert 68 has fold
regions 70. Folded reinforcing insert 68 is roll formed metal.
[0036] Referring now to FIG. 7 of the drawings, I-beam 72 is shown
which is formed by casting a foam cement material. More
specifically, it has been found that a Portland cement-based I-beam
72 is desirable for use in the present invention. The Portland
cement-based material has a combination of microspheres or cement,
water and silica fume.
[0037] In the following tables, preferred formulations for the
cement-water based mixes for I-beam 72 are set forth.
2 FORMULA I FORMULA II (STANDARD MIX) (LIGHTWEIGHT MIX) INGREDIENT
(PARTS BY WEIGHT) (PARTS BY WEIGHT) Cement 54% 54% Water 24% 24%
Density Dry Cement 40 PCF 40 PCF Mix Density Wet 56 PCF 40 PCF
Cement Mix
[0038] The standard mix is made with an equal volume of cement.
Portland Type IA or Type I as defined in the book of the Portland
Cement Association entitled "Design and Control of Concrete
Mixtures" Eleventh Edition (Library of Congress catalog card number
29-10592) and an equal volume of microspheres.
[0039] The bulk of the density of the Portland Type I A cement is
approximately 75 to 30 pounds per cubic feet. The bulk density of
the microspheres is 15 pounds per cubic feet. By combining the two
in equal amounts the specific gravity of the combined mix dry is 25
to 40 pounds per cubic feet of approximately one half the weight of
the cement.
[0040] The amount of water added to the mix is between 35 to 50
percent of the weight of the cement. Thus, if the mix has 800 grams
of cement 400 grams of water would be added. The mix has 220 to 650
grams of the microspheres.
[0041] The Portland Cement/microspheres combination is improved in
its moisture resistance characteristic by the addition of silica
fume. Silica fume is a dust material collected from flu gas stacks.
The silica dust are tiny inert particles, typically about 15
microns in diameter. When the silica inert particles are added to
the dry cement mix, the particles clog the interstitial spaces
between the cement particles and the microspheres. The silica fume
particles clog the pores between the cement and thereby vastly
improve the moisture resistance of the cured product. The amount of
silica fume added is preferably from about 10 to 20 percent by
weight of cement.
[0042] There are two versions of silica fume, one treated and the
other one not treated. The treated silica fume has a plasticizer
which also lubricates the mix and reduces the water content
further.
[0043] To increase the moisture resistance of the finished product
other materials can be used in place of the silica fume. These are
water born materials such as a latex manufactured by Dow Chemical
Co. of Midland Michigan, or a water base urethane, acrylic, or
epoxy. Such materials have the characteristic of clotting the inner
spaces between the cement particles. Silica fume will actually
combine chemically with the cement and will improve the properties
of the cement. The latex does not chemically combine with the
cement, but it can be used to clot the cement pores and thereby
reduce the water to cement ratio. The water base urethane, acrylic
and epoxies produce the same result of clotting as a latex or
silica fume.
[0044] While particular embodiments of this invention are shown and
described herein, it will be understood, of course that the
invention is not to be limited thereto since many modifications may
be made, particularly by those skilled in this art, in light of
this disclosure. It is contemplated therefore by the appended
claims, to cover any such modifications as fall within the true
spirit and scope of this invention. Thus, although the invention
has been described with particular reference to reinforcing
automotive parts, the invention may be practiced for reinforcing
other parts. Examples of such other parts are aircraft, furniture,
appliances and farm equipment. Still other parts will be apparent
to those of ordinary skill in the art, given the teachings of the
invention.
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