Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
PARKING STOP MADE FROM RECYCLED TIRES
FIELD OF THE INVENTION
This invention relates to the recycling of scrap automobile and truck tires
into useful products.
BACKGROUND OF THE INVENTION
Disposing of scrap tires has become a very large environmental problem.
Millions of worn out automobile and truck tires are presently being stored in
enormous
piles or filling canyons. These piles result in visual pollution and sometimes
catch fire,
with the resulting large, dense, smoke plumes polluting the air for miles down
wind. In
addition liquid hydrocarbons may be released into the ground water due to
pyrolitic
reactions as the tires are heated, then burned. These tire pile fires are very
difficult to
extinguish.
Tires are presently being recycled on a very limited scale. Some are
ground into particles useful in road building. Others are used in the creation
of artificial
reefs to improve lake and ocean fishing. Some are used for barriers around go-
cart
race tracks. Presently, recycling is consuming fewer tires than are being
added to the
waste stream.
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Attempts have been made to recycle at least parts of tires into structural
beams and the like. For example, Snyder in U.S. Patent No. 5,096,772 describes
a
beam forming process in which the sidewalls of tires are cut away, the rubber
tread
portion is sliced away from the steel belts. A thin layer of rubber is
vulcanized to the
belts and the belts are laminated together. However, this process uses only a
small
percentage of the tire, requires a complex layup to assure that the tire cords
are
arranged in different directions in succeeding layers and is quite costly.
Tripp in U.S. Patent No. 5,340,630 describes a process for recycling the
tread portion of tires in which the sidewalls are cut away, the tread portions
are joined
end to end to form two elongated continuous plies, then the two plies are
bonded
together to form a long two-ply member. This member can be used as a building
material. However, this process is limited to a two ply thickness, is subject
to
delamination and is not directly useful as a product other than in fabricating
other
structu res.
Similarly, in U.S. Patent No. 5,412,921, Tripp describes a method of
making a structure similar to an I-beam from the elongated plies made in his
earlier
patent, with plies forming the faces of the I-beam and two plies together
forming the I-
beam flange. This is a complex, difficult to secure together, assembly. Figure
6 of the
Trip '921 drawing clearly shows the curvature of tire treads that makes
difficult the
bonding of two plies together to form a double-ply member.
Miller discloses, in U.S. Patent No. 5,472,750, a method of producing
large, thick, mats from tires which includes the steps of slitting the
sidewalls and
pressing the tire flat to form a preform having a rectangular center area
conforming to
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the tread and a saw-toothed edge corresponding to the sidewalls, then stacking
and
bonding these preforms. Problems remain in truly flattening the preforms due
to lesser
sidewall thickness relative to tread thickness. In particular, obtaining tight
interlocking of
the saw-toothed edges is difficult, since this pattern conforms to the
sidewall diameter
and sidewall diameters vary greatly.
In U.S. Patent No. 5,834,083. Pignataro, Jr. describes a tire recycling
process including removing sidewalls from the tires, cutting the tread
transversely to
form strips, fastening the strips with interlocking dovetails and bonding
strips together.
This process is difficult and requires high accuracy in cutting dovetails. Due
to the
curvature of the inner surface of the tread material, bonding is difficult and
likely to result
in bubble formation or central separation of the lamination.
In general, the bonding together of tire tread strips to form two or more ply
laminations has been very difficult and likely to result in delamination in
use as a
structural member. The edges of the tread strips, which curve toward the
sidewalls,
have a lesser circumference. Or, said another way tread strip edges have a
shorter
length than the strip centerline when laid flat. This difference makes
flattening the tread
very difficult.
Therefore, there is a continuing need for improvements in guard rail
systems that recycle portions of used tires, that are strong and resilient,
are highly
resistant to impact damage, that will not deteriorate when exposed to severe
weather
and freeze/thaw cycles and that can be provided with a reinforcing surface
coating
having any desired color.
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SUMMARY OF THE INVENTION
The above-noted problems, and others, are overcome by recycling scrap
automobile, truck, etc., tires into a parking stop which is superior to
present concrete
parking stops. The parking stops comprise a plurality of tread strips cut from
worn out
tires, the strips having slits along the long edges extending transversely
toward the strip
centerline, with the strips laminated together in a face-to-face manner with
similar sides
in contact, i.e., tread surface to tread surface and inside surface to inside
surface.
Any suitable means may be used to secure the strips together. Typically,
adhesive bonding and/or mechanical fasteners such as staples and/or ring nails
may
be used.
Preferably, pairs of strips are bonded together to produce slats, then
these slats are secured together to the desired thickness. Typically, the
slats have
widths of about six to eight inches. The slats have lengths typically in the
range of about
five to eight feet. Parking stops of any length can be produced by trimming
the slats for
shorter stops or laminating slats in a staggered manner for longer stops.
Generally, two
adjacent long edges of the laminated structure are trimmed away to produce a
parking
stop having a configuration similar to that of conventional concrete stops.
The completed parking stop may be coated with any suitable coating
having any desired color. The polyurethane based coatings of the sort
presently used
for coating pick up truck beds is preferred for adding strength to the
lamination.
The parking stops are made by a process that comprises the steps of
removing the tire sidewalls (which can be ground for road building particles
or other
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uses), cutting the tread portion transversely to form an elongated strip,
slitting the strip
edges transversely inward toward the tread longitudinal centerline to a depth
of from
about one inch to about the tread longitudinal centerline about every 1 to 4
inches to
form a slat useful in manufacturing various structures. The slits are
preferably evenly
staggered, with a slit on one side spaced equally between slits on the
opposite side.
These slats may then be secured together in unitary pairs, then additional
slats(individual or added unitary pairs) may be secured to both sides of the
first unitary
pair to provide any suitable number of tread laminations to produce the
desired product
thickness. While adhesive bonding of slats is optimum in most cases, producing
an
outstanding combination of strength, resiliency and resistance to separation,
mechanical fasteners, such as staples or ring nails, may be used if desired.
In some
cases both adhesive bonding and mechanical fasteners may be used.
It is desirable that the slats be trimmed to a selected width for
corresponding to the parking stop width desired. For example, automobile tires
can be
cut to a 6 inch width, with truck tires capable of producing slats having 7 to
10 inch
widths. Automobile tires produce slats having lengths of approximately 5 to 8
feet,
while truck tire slats have lengths of approximately 6 to 9 feet. These slats
can be cut to
any desired lesser length.
The exterior of a laminated parking stop structure may coated with any
suitable material to seal the surtace and provide a desired color. In a
particularly
preferred embodiment, a coating of a high strength elastomer. This will
provide an
attractive surface of any desired color and will further reinforce the
structure. With such
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a coating, staples or other mechanical fasteners are generally sufficient to
secure the
slats together.
BRIEF DESCRIPTION OF THE DRAWINGS
Details of the invention, and of preferred embodiments thereof, will be
further understood upon reference to the drawing, wherein:
Figure 1 is an exploded perspective view of a tire with the sidewalls cut
away and the tread portion transversely cut;
Figure 2 is a cross section through the tire showing the preferred lines
along which the tire sidewalls are cut;
Figure 3 is a plan view of a tread portion slat with spaced edge slits;
Figure 4 is a transverse section through an assembly formed from four
tread slats;
Figure 5 is an exploded perspective view of a parking stop;
Figure 6 is a transverse section view through the parking stop of Figure 5
with an added elastomer coating;
Figure 7a is a perspective view of a first embodiment of a guard rail
using a plurality of slats;
Figure 7b is a perspective view of a second embodiment of a guard rail;
Figure 7c is a perspective view of a second embodiment of a guard rail;
Figure 8 is a perspective view of a beam formed from a plurality of slats;
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Figure 9 is a perspective view, partly cut-away, of a panel made of plural
layers of strips;
Figure 10 is a flow diagram of a first embodiment of the process of this
invention; and
Figure 11 is a flow diagram of a second embodiment of the process.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to Figures 1 and 2, there is seen a tire 10 having a circular strip
12 which is basically the tread portion of the tire and two sidewalls 14.
Typically, tire 10
is a conventional automobile or truck tire, which is worn to the point where
the depth of
tread grooves 16 is too shallow for safe use of the tire on a vehicle. Other
pneumatic
tires, such as those used on golf carts, bicycles and the like could be used,
although the
numbers of those tires available is quite small.
Sidewalls 14 are trimmed from the strip 12 by any suitable means. Any
suitable trim line may be used. Optimally, the trim line is approximately at
line 22 in
Figure 2, at the line where the thickness of the sidewall expands to become
tread, but
outside of the belt cords 20.
Once sidewalls 14 have been removed, strip 16 is cut transversely at line
21, producing a long rectangular strip, typically about 6.5 feet for
automobile tires with
truck tire slats somewhat longer. The sidewalls may be recycled in any
suitable manner.
As can be seen in Figure 2, strip 12 is rounded or crowned, with the
edges having a smaller circumference than the central portion of the tread. In
the prior
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art, attempts were made to bond such strips 12 together. However, since the
strip 12
edges are shorter than the central area, the slats will not lie flat. If
coated with an
adhesive and pressed into a flat assembly of two or more strips 12, initially
the laminate
may appear to be flat and uniform. However, the high internal tension inherent
in such
an assembly will cause the assembly to delaminate and/or bubble at the strip
interfaces, result in great weakening and loss of structural integrity.
As seen in Figure 3, cutting slits 24 into the edges of tread strip 12 will
produce a slat 15 that is flat and therefore is a preform suitable for the
manufacture of a
variety of structures. Preferably, the tread strip 12 is trimmed to a desired
width before
cutting the slits. Trim lines 23 in Figure 2 show a preferred trim line.
The slits 24 are critical to the effectiveness of the process and the
structural integrity and strength of the products produced. For a slat 15 cut
from an
automobile or truck tire having a width of about six inches, the slits are
preferably
spaced about one to four inches apart and have depths of from about one inch
to about
the centerline of the strip. Optimally, the slits are spaced about three
inches apart and
have depths of about two inches. For slats 15 cut from truck tires with slat
widths of
about seven or eight inches, the optimum slit spacing is about three inches
and slit
depth is inward to about 40% of the slat width.
In constructing a laminated product, initially two slats 15 are bonded
together, preferably by an adhesive although staples or other fasteners may be
used in
some cases, as described below. The slats 15 are bonded face-to-face with
similar
sides in contact; that is, grooved outer surfaces together or smooth inner
surfaces
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together. Preferably the surfaces of slats 15 are buffed or abraded to remove
any
contaminants and improve adhesive bonding.
To build up a thick, beam-like, structure, additional pairs of slats 15 are
bonded to the two initial slats to form a beam 26 as seen in Figure 4.
Preferably, same
sides are always bonded together to cancel out crown effects. Thus, as shown
in
Figure 4, the inner surfaces of the next slats are bonded to inner surfaces of
the first
pair of slats. In a preferred arrangement, pairs of slats are bonded together,
inside
surface to inside surface, then these two-slat preforms are further stacked
and bonded
together to produce structures of the desired thickness, e.g. four, six or
eight slats thick.
One preferred final product for this process is a parking stop as seen in
Figure 5. The two upper corners 28 are cut away to leave a beveled upper
surface 30.
Two or more holes 32 are drilled through the beam to receive stakes or the
like to hold
the parking stop in place. This is a highly effective parking stop that is
resilient with
some give upon impact. The parking stop will not break when impacted or
subjected to
freeze-thaw cycles as happens with concrete stops and will absorb energy when
the
impact is higher than normal, avoiding damages to either the vehicle or the
parking
stop.
An alternate embodiment of a parking stop is illustrated in Figure 6.
Here, beam 26, after the upper corners are removed, a coat 34 of an elastomer
is
applied to the beam. Preferably all external surfaces are coated. The coating
should
have a thickness of at least about 1/8 in., with coatings having thickness in
the range of
from about 1/8 to 3/8 in. being preferred. The elastomer coating may have any
desired
color, e.g. blue for handicapped parking spaces. Any suitable elastomer
coating may
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be used. Typical coatings are those applied by spraying to pick up truck beds
and the
like. Such coatings are available from the Bullhide~ Corporation, Rhino~
Linings,
Quarry Coatings, Techthane~ Elastomers and others and generally comprise a
polyurethane resin.
While the slats 15 making up beam 26 may be bonded together with an
adhesive, as described above, mechanical fasteners such as ring nails or the
like may
be used in the manufacture of this embodiment, if desired, since coating 34
assists in
maintaining the beam structure. The ring nails should include nails 37
inserted from the
bottom of the structure, closely adjacent to where bevel 41 begins and nails
39 inserted
from the flat top portion 43 adjacent to bevel 41. Alternatively, ring nails
could be
inserted through the top of the beam near the bevels to be parallel to the
bevels and an
additional nail could be inserted through the top perpendicular to the top.
Another preferred product is illustrated in Figure 7a. Here, a guard rail
system 38 is made up of laminated beams 26. Posts 40 have slats running
vertically
and have a suitable length for embedding a suitable distance into the ground.
A notch
42 is cut into the upper ends of posts 40 to receive an elongated rail 44
having a cross
section of the sort shown in Figures 5 and 6. Rails 44 preferably extend out
from posts
40 to receive the initial impact of a vehicle striking rail system 38. Because
of the
resiliency of rails 44 and posts 40, the system will give somewhat with
impact,
absorbing impact energy and reducing damage to the impacting vehicle, as would
happen with a rigid guard rail. Once the impacting vehicle is removed, the
rails will
substantially return to their original position rather than bending and
crushing as is the
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case with conventional metal rails. Rails 44 may be secured to posts 40 by any
suitable means, such as the through bolts 46 shown, lag screws, adhesives,
etc.
A second embodiment of a guard rail system 38 is shown in Figure 7b.
Here, a square or rectangular rail 44 is mounted in a large notch 50 in post
52. This
arrangement has energy absorbing characteristics and ability to return to
shape after
impact as described above. Because of the greater contact area between rail 48
and
notch 50, an adhesive bonding between post and rail will generally be
sufficient.
However, bolts, screws or the like may be used as a further reinforcement of
the
attachment, if desired.
A third embodiment of a guard rail system 38 is shown in Figure 7c.
Here, post 53 is rectangular in cross section over its entire length,
including the portion
extending below ground level 55. Rail 55 is secured to the side of post 53 by
a through
bolt 46 or the like. Preferably the head of bolt 46 is recessed, as seen in
the cut-away
portion of rail 55.
As shown in Figure 8, walls or other large panels 54 may be formed from
the beams 26 produced by laying up slats 15. Each beam will have a length of
around
6 to 8 feet, depending on the circumference of the tires used. These beams 26
may be
bonded together in a staggered relationship with adhesives, screws, or other
suitable
fasteners as desired. The lengths of beams 26 may be trimmed to provide
shorter
pieces for wall ends, corners and the like.
Walls 54 made as described will be strong and resilient, resistant to
impacts that would cause cracking in a concrete block wall. These walls may be
coated with an elastomer coating of any desired color, as described above.
Walls 54
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are particularly suitable for use in building tornado rooms and the like
because of their
strength and resiliency.
Another preferred structure using the slats of this invention is shown in
Figure 9. Here, a plurality of slats 26 of predetermined thickness are laid up
adjacent
to each other to form overlying layers 58 producing a flexible, high strength
panel or mat
56. The direction of layers 58 is rotated 90° fram layer to layer to
provide maximum
strength in each direction.
The abutting edges of the slats 26 in each layer 58 may be bonded with
any suitable adhesive. Each layer may be secured to contiguous layers in any
suitable
manner, such as with an adhesive or mechanical fasteners. Ring nails are
preferred
where mechanical fastening is chosen. Panel 56 is both strong and resilient
and can
be used as a structural member in construction, and is particularly suitable
for school
playgrounds, railroad crossing mats, etc.
A first preferred embodiment of the process of manufacturing various
laminated products from worn out tires is summarized in the flow diagram of
Figure 10.
Initially, the worn out are taken to the manufacturing facility as indicated
in
block 62.
The first manufacturing step is removing the sidewalls from the carcass
as indicated in block 64, typically by cutting with a knife, sawing etc. This
leaves a
circular tread strip, with edges that inherently have a smaller circumference
than the
center portion of the tread.
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The circular strip is cut transversely, as indicated in block 66 to produce
an approximately rectangular strip. The strip at this point will not lie flat
and, if bonded to
another strip under high pressure, will tend to bubble or delaminate in use.
The strip is then cut to the desired width, as indicated in block 68.
Typically, the strip is trimmed with a band saw or other suitable saw.
Spaced slits are cut into the long edges of the strip, as indicated in block
70, with the spacing and depth described above, to produce the flat slat 15 as
described above. These slits are critical to durable bonding, since they allow
the slat to
lie flat because the tensions in the edges that are shorter than the
longitudinal centerline
of the slat are relieved.
Two slats are then pressed and secured together, as indicated in block
72 with similar faces in contact. That is, either two outer, tread bearing
surfaces or two
inner, smooth surfaces are secured together. In most cases, the slats are
preferably
bonded by flexible adhesive. Mechanical fasteners may be used in place of the
adhesive, or in addition to that adhesive, if desired. Preferably, the slats
are pressed
at a pressure of from about 100 to 200 psi.
Additional bonded pairs of slats are then secured to the first two to layup
the desired overall beam thickness desired, as indicated in block 74. The
added slats
preferably are secured with similar faces in contact, that is, tread surface
to tread
surface or smooth inner surface to smooth inner surface. This arrangement is
important
to obtaining a straight beam, since bonding other surfaces may distort the
beam due to
the tire tread inherent crown.
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Typically, the slats are bonded in a press, such as one using an open-
topped mold conforming to the slat width and length, with a sturdy steel beam
extending
the length of the opening and hydraulic pistons to press the beam down against
a stack
of slats in the mold. Where the slats are to be secured together with an
adhesive that is
applied to the contacting surfaces before placement in the mold. Where the
slats are to
be secured together with a mechanical fastener, such as ring nails or staples,
openings
may be provided in the beam through which the fasteners may be installed with
a
conventional nail gun.
The beams produced in block 74 may be cut to length as indicated in
block 76. Or, they may be trimmed to a desired configuration as indicated in
block 80.
Typically, the configuration may by the parking stop shown in Figures 5 and 6.
The final shaped beam may be coated with a thick elastomer coating of
any desired color, as indicated in block 78. The steps in the sequence of
Figure 11
may be varied, where suitable and other modifications may be made to slats and
beams between the basic series of steps shown.
An alternative embodiment of the process of this invention is illustrated in
the block diagram of Figure 11. The initial steps are the same as described in
conjunction with the description of Figure 10. Tires are selected and provided
to the
manufacturing facility, as indicated in block 84. The sidewalls are removed as
indicated in block 86. The tubular strip is then cut transversely as indicated
by block 88
to produce an approximately rectangular strip, which is cupped towards the
inside due
to the smaller tire edge circumference, as detailed above. The strip is then
trimmed to
width as shown in block 90.
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LJ
In a critical step, the long edges of the strip are slit transversely to the
optimum degree, as detailed above and indicated in block 92. While the slits
on
opposite sides may have any suitable relationship, the slits preferably
staggered along
the sides, with a slit on one side between slits on the opposite side.
Preferably the
surfaces of slats 15 are buffed or abraded to remove any contaminants and
improve
adhesive bonding.
A predetermined number of strips having approximately equal lengths
and widths are prepared as described above. A first strip is coated on one
side and
placed in a mold that resembles an open topped box, with the coating upwards.
Additional strips are coated with adhesive on both sides and placed one at a
time in
the mold, as indicated by block 96. A final strip is coated and placed
adhesive side
down on the stack. This coating series is indicated in block 94. A press
platen, typically
a steel beam having a surface corresponding to the opening in the mold is
placed over
the stack of strips and pressed against the stack, typically by hydraulic
cylinders, as
indicated in block 98.
The press platen has a plurality of small, spaced openings exposing the
top of the strip stack. Mechanical fasteners, such as staples or ring nails,
may be
inserted into the stack through these holes by a conventional nail gun.
This process produces an extremely sturdy final product, with the strips
very securely fastened together. If desired, depending on the adhesive
selected, only
one of each pair of abutting strip surfaces could be coated with adhesive,
rather than
coating both surfaces. Further, if desired, either the adhesive coating or the
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mechanical fasteners could be omitted without severely weakening product
structural
integrity.
While certain specific relationships, materials and other parameters have
been detailed in the above description of preferred embodiments, those can be
varied,
where suitable, with similar results. Other applications, variation and
ramifications of
the present invention will occur to those skilled in the art upon reading the
present
disclosure. Those are intended to be included within the scope of this
invention as
defined in the appended claims.
