Note: Descriptions are shown in the official language in which they were submitted.
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POLYURETHANE SCREEN
CROSS-REFERENCE TO RELATED APPLICATIONS
The present disclosure is related to U.S. Patent Application Serial No.
13/838,968,
entitled "Polyurethane Vibratory Screen," filed on March 15, 2013, which is
related
to U.S. Patent Application Serial No. 12/763,046 now U.S. Patent No.
8,584,866, filed
on April 19, 2010.
FIELD OF THE INVENTION
The present invention relates to an improved molded polyurethane screen.
BACKGROUND
Molded polyurethane screens having reinforcement therein are known in the art.
However, in the past the dividing strips between the openings were relatively
large,
thereby causing the open area of the screen to be an undesirably low
percentage of its
surface, thereby in turn causing the screen to be relatively inefficient.
The present invention is an improvement over U.S. Patent Nos. 4,819,809 and
4,857,176. The present invention provides improved screens with relatively
high
percentage open screening areas and high efficiencies.
The present invention also provides improved screens and screen deck
assemblies that
may be used in screening machines such as those described in U.S. Patent Nos.
6,070,736, 8,113,358, 8,522,981, and U.S. Patent Pub. No. 2011/0036759.
These screening machines, referred to as attrition screening devices,
including for
example, sifters, gyratory sifters, or graters, include a class of vibratory
devices used
.. to separate sized particles, as well as to separate solids from liquids.
Sifters are used to
screen, for example, minerals, feed materials, plastic resins, and powders
during
industrial sorting and/or manufacturing operations.
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Because sifters may be in continuous use, repair operations and associated
downtimes
need to be minimized as much as possible. Sifters currently include screening
assemblies that have a plate or frame as a base and a wire mesh, cloth, or
other
perforated filter overlay positioned as a screen over the plate or frame.
These filter
screens often wear out over time due to the particular motion in the sifters,
and
subsequently require replacement. Screens currently being used in these
sifters often
wear out in three weeks or less. Also, woven wire cloth screens are
problematic in
that they can have inconsistent openings, sizes, or other irregularities due
to
inaccuracies in the weaving process.
Existing screens used in sifters are generally placed on a "ball tray" or
"ball box" that
captures a number of balls or other agitation producing members which
repeatedly
impact the screen assembly to dislodge particulate material that accumulates
in the
screen openings and thus helps de-blind the screens. Blinding is often a
serious
problem with woven wire cloth screens. The ball tray or box is cumbersome, has
loose balls, and is often heavy. In some instances, the screens and/or ball
trays or
boxes in sifters have to be replaced at least twice a week. Further, the
specific motion
of the sifter may cause the ball trays or boxes to emit hazardous particles
into the air
that may then affect the health and safety of the operators of these sifting
screening
machines. Accordingly, a need exists for screens and screen deck assemblies to
be
used in these sifting screening machines that are safer, longer lasting, more
easily
removable and replaceable, lighter, provide more consistent and accurate
opening
sizes than existing screens, and reduces blinding problems without the use of
multiple
loose impact objects.
SUMMARY
According to an exemplary embodiment of the present invention, a vibratory
screen
includes: a flexible molded polyurethane body having substantially parallel
side edge
portions at opposite ends of the body, a lower edge portion substantially
perpendicular
to the side edge portions, an upper edge portion substantially perpendicular
to the side
edge portions and opposite the lower edge portion, an upper surface, a lower
surface,
first and second members forming screening openings and third and fourth
members.
The first members extend between the side edge portions. The second members
extend between the lower edge portion and the upper edge portion. The third
and
fourth members may have a thickness greater than the first and second members.
The
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third members are substantially parallel and extend transversely between the
side edge
portions and have multiple first members therebetween. The fourth members are
substantially parallel and extend transversely between the lower edge portion
and the
upper edge portion and have multiple second members therebetween.
Reinforcement
members are molded integrally with the third and fourth members.
In an example embodiment of the present disclosure, a screen deck assembly is
provided that includes a support deck and a first screen, second screen, and
third
screen. Each screen may include a flexible molded polyurethane body having
substantially parallel side edge portions at opposite ends of the body, a
lower edge
portion transversely disposed between the side edge portions, an upper edge
portion
disposed between the side edge portions and substantially parallel and
opposite to the
lower end portion, an upper surface, a lower surface, a first integrally
molded grid
structure, a second integrally molded grid structure, and a third integrally
molded grid
structure and screen openings. The first grid structure may include first and
second
members forming the screening openings. The first members may be substantially
parallel and extend transversely between the side edge portions. The second
members
may be substantially parallel and extend transversely between the lower edge
portion
and the upper edge portion. The second grid structure may include third and
fourth
members. The third members may be substantially parallel and extend
transversely
between the side edge portions and have multiple first members therebetween.
The
fourth members may be substantially parallel and extend transversely between
the
lower edge portion and the upper edge portion and have multiple second members
therebetween. The third grid structure may include fifth and sixth members.
The fifth
members may be substantially parallel and extend transversely between the side
edge
portions and have multiple third members therebetween. The sixth members may
be
substantially parallel and extend transversely between the lower edge portion
and the
upper edge portion and have multiple fourth members therebetween. A
reinforcement
member may be molded integrally with at least one of the first, third, and
fifth
members and at least one of the second, fourth, and sixth members. The first
members
may include reinforcement members molded integrally therewith, the
reinforcement
members having a thickness in the range of about .006 inches to about .015
inches.
The second members may include reinforcement members molded integrally
therewith, the reinforcement members having a thickness in the range of about
.015
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inches to about .040 inches. The side edge portions of each of the first,
second, and
third screens may include attachment arrangements configured to secure the
screens
to the support deck. The side edge portions of the first, second, and third
screens may
be secured to the support deck. The first, second, and third screens may be
tensioned
across the support deck. The first, second, and third screens are tensioned
using a
plurality of spring clips attached to the support deck. The attachment
arrangement
may be a grommet. The screen deck assembly may further comprise a cast-in
tension
strip located within each of the side edge portions such that tension loads
applied to
the side edge portions are distributed across the screen. The side edge
portions may
include apertures configured to fill up with polyurethane and suspend the cast-
in
tension strip in place within the side edge portions of the screen. The screen
deck
assembly may further comprise an overlap sealing member extending away from an
outer edge of at least one of the lower edge portion and the upper edge
portion of at
least one of the screens. The sealing member may be formed as part of the
screens.
The sealing member may also be formed as a separate member from the screens.
The
screen openings may be about .044 mm to about 4 mm between inner surfaces of
the
first members and about .044 mm to about 60 mm between inner surfaces of the
second members. The reinforcement members may be molded integrally with the
first
and second members. The reinforcement rods may be molded integrally with at
least
one of the fourth and sixth members. The reinforcement members may also be
molded
integrally with the third and fourth members. The reinforcement rods may be
molded
integrally with at least one of the fourth and sixth members. The
reinforcement
members may be molded integrally with the fifth and sixth members. The
reinforcement rods may be molded integrally with at least one of the fourth
and sixth
members.
In an example embodiment of the present disclosure, a screen is provided that
includes a flexible molded polyurethane body having substantially parallel
side edge
portions at opposite ends of the body, a lower edge portion transversely
disposed
between the side edge portions, an upper edge portion disposed between the
side edge
portions and substantially parallel and opposite to the lower end portion, an
upper
surface, a lower surface, a first integrally molded grid structure, a second
integrally
molded grid structure, and a third integrally molded grid structure and screen
openings. The first grid structure may include first and second members
forming the
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screening openings. The first members may be substantially parallel and extend
transversely between the side edge portions. The second members may be
substantially parallel and extend transversely between the lower edge portion
and the
upper edge portion. The second grid structure may include third and fourth
members.
The third members may be substantially parallel and extend transversely
between the
side edge portions and have multiple first members therebetween. The fourth
members may be substantially parallel and extend transversely between the
lower
edge portion and the upper edge portion and have multiple second members
therebetween. The third grid structure may include fifth and sixth members.
The fifth
members may be substantially parallel and extend transversely between the side
edge
portions and have multiple third members therebetween. The sixth members may
be
substantially parallel and extend transversely between the lower edge portion
and the
upper edge portion and have multiple fourth members therebetween. A
reinforcement
member may be molded integrally with at least one of the first, third, and
fifth
members and at least one of the second, fourth, and sixth members. The first
members
may include reinforcement members molded integrally therewith, the
reinforcement
members having a thickness in the range of about .006 inches to about .015
inches.
The second members may include reinforcement members molded integrally
therewith, the reinforcement members having a thickness in the range of about
.015
inches to about .040 inches. The side edge portions of the screen may include
attachment arrangements configured to secure the screen to a structural
member. The
side edge portions of the first, second, and third screens may be secured to
the support
deck. The attachment arrangement may be a grommet. The screen may further
comprise a cast-in tension strip located within each of the side edge portions
such that
tension loads applied to the side edge portions are distributed across the
screen. The
side edge portions may include apertures configured to fill up with
polyurethane and
suspend the cast-in tension strip in place within the side edge portions of
the screen.
The screen may further comprise an overlap sealing member extending away from
an
outer edge of at least one of the lower edge portion and the upper edge
portion of at
least one of the screens. The sealing member may be formed as part of the
screen. The
sealing member may also be formed as a separate member from the screen. The
screen openings may be about .044 mm to about 4 mm between inner surfaces of
the
first members and about .044 mm to about 60 mm between inner surfaces of the
second members. The reinforcement members may be molded integrally with the
first
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and second members. The reinforcement rods may be molded integrally with at
least
one of the fourth and sixth members. The reinforcement members may also be
molded
integrally with the third and fourth members The reinforcement rods may be
molded
integrally with at least one of the fourth and sixth members. The
reinforcement
members may be molded integrally with the fifth and sixth members. The
reinforcement rods may be molded integrally with at least one of the fourth
and sixth
members.
In an example embodiment of the present disclosure, a method for separating
materials is provided that includes installing a screen deck assembly in an
attrition
screening device and sifting the materials. The screen deck assembly includes
a
support deck and a screen. The screen may include a flexible molded
polyurethane
body having substantially parallel side edge portions at opposite ends of the
body, a
lower edge portion transversely disposed between the side edge portions, an
upper
edge portion disposed between the side edge portions and substantially
parallel and
opposite to the lower end portion, an upper surface, a lower surface, a first
integrally
molded grid structure, a second integrally molded grid structure, and a third
integrally
molded grid structure and screen openings. The first grid structure may
include first
and second members forming the screening openings. The first members may be
substantially parallel and extend transversely between the side edge portions.
The
second members may be substantially parallel and extend transversely between
the
lower edge portion and the upper edge portion. The second grid structure may
include
third and fourth members. The third members may be substantially parallel and
extend transversely between the side edge portions and have multiple first
members
therebetween. The fourth members may be substantially parallel and extend
transversely between the lower edge portion and the upper edge portion and
have
multiple second members therebetween. The third grid structure may include
fifth and
sixth members. The fifth members may be substantially parallel and extend
transversely between the side edge portions and have multiple third members
therebetween. The sixth members may be substantially parallel and extend
transversely between the lower edge portion and the upper edge portion and
have
multiple fourth members therebetween. A reinforcement member may be molded
integrally with at least one of the first, third, and fifth members and at
least one of the
second, fourth, and sixth members. The first members may include reinforcement
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members molded integrally therewith, the reinforcement members having a
thickness
in the range of about .006 inches to about .015 inches. The second members may
include reinforcement members molded integrally therewith, the reinforcement
members having a thickness in the range of about .015 inches to about .040
inches.
The side edge portions of each of the first, second, and third screens may
include
attachment arrangements configured to secure the screens to the support deck.
The
side edge portions of the first, second, and third screens may be secured to
the support
deck. The reinforcement members may be molded integrally with the first and
second
members. The reinforcement rods may be molded integrally with at least one of
the
fourth and sixth members. The reinforcement members may also be molded
integrally
with the third and fourth members. The reinforcement rods may be molded
integrally
with at least one of the fourth and sixth members. The reinforcement members
may be
molded integrally with the fifth and sixth members. The reinforcement rods may
be
molded integrally with at least one of the fourth and sixth members.
In an example embodiment of the present disclosure, a system for separating
materials
is provided that includes an attrition screening device and a screen deck
assembly
installed in the attrition screening device for separating the materials. The
screen deck
assembly includes a support deck and a screen. The screen may include a
flexible
molded polyurethane body having substantially parallel side edge portions at
opposite
ends of the body, a lower edge portion transversely disposed between the side
edge
portions, an upper edge portion disposed between the side edge portions and
substantially parallel and opposite to the lower end portion, an upper
surface, a lower
surface, a first integrally molded grid structure, a second integrally molded
grid
structure, and a third integrally molded grid structure and screen openings.
The first
grid structure may include first and second members forming the screening
openings.
The first members may be substantially parallel and extend transversely
between the
side edge portions. The second members may be substantially parallel and
extend
transversely between the lower edge portion and the upper edge portion. The
second
grid structure may include third and fourth members. The third members may be
substantially parallel and extend transversely between the side edge portions
and have
multiple first members therebetween. The fourth members may be substantially
parallel and extend transversely between the lower edge portion and the upper
edge
portion and have multiple second members therebetween. The third grid
structure may
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include fifth and sixth members. The fifth members may be substantially
parallel and
extend transversely between the side edge portions and have multiple third
members
therebetween. The sixth members may be substantially parallel and extend
transversely between the lower edge portion and the upper edge portion and
have
multiple fourth members therebetween. A reinforcement member may be molded
integrally with at least one of the first, third, and fifth members and at
least one of the
second, fourth, and sixth members. The first members may include reinforcement
members molded integrally therewith, the reinforcement members having a
thickness
in the range of about .006 inches to about .015 inches. The second members may
include reinforcement members molded integrally therewith, the reinforcement
members having a thickness in the range of about .015 inches to about .040
inches.
The side edge portions of each of the first, second, and third screens may
include
attachment arrangements configured to secure the screens to the support deck.
The
side edge portions of the first, second, and third screens may be secured to
the support
deck. The reinforcement members may be molded integrally with the first and
second
members. The reinforcement rods may be molded integrally with at least one of
the
fourth and sixth members. The reinforcement members may also be molded
integrally
with the third and fourth members. The reinforcement rods may be molded
integrally
with at least one of the fourth and sixth members. The reinforcement members
may be
molded integrally with the fifth and sixth members. The reinforcement rods may
be
molded integrally with at least one of the fourth and sixth members.
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In an example embodiment of the present disclosure, there is provided a screen
deck
assembly, comprising: a support deck; a first screen, second screen, and third
screen, each
screen including a flexible molded polyurethane body having substantially
parallel side edge
portions at opposite ends of the body, a lower edge portion transversely
disposed between the
side edge portions, an upper edge portion disposed between the side edge
portions and
substantially parallel and opposite to the lower end portion, an upper
surface, a lower surface, a
first integrally molded grid structure, a second integrally molded grid
structure, a third integrally
molded grid structure and screen openings, wherein the first grid structure
includes first and
second members forming the screening openings, the first members substantially
parallel and
extending transversely between the side edge portions and the second members
substantially
parallel and extending transversely between the lower edge portion and the
upper edge portion,
wherein the second grid structure includes third and fourth members, the third
members
substantially parallel and extending transversely between the side edge
portions and having
multiple first members therebetween, the fourth members substantially parallel
and extending
transversely between the lower edge portion and the upper edge portion and
having multiple
second members therebetween, wherein the third grid structure includes fifth
and sixth
members, the fifth members substantially parallel and extending transversely
between the side
edge portions and having multiple third members therebetween, the sixth
members substantially
parallel and extending transversely between the lower edge portion and the
upper edge portion
and having multiple fourth members therebetween, wherein reinforcement members
are molded
integrally with at least one of the first, third, and fifth members and at
least one of the second,
fourth, and sixth members, wherein the side edge portions of each of the
first, second, and third
screens include attachment arrangements configured to secure the screens to
the support deck,
wherein the side edge portions of the first, second, and third screens are
secured to the support
deck.
In an example embodiment of the present disclosure, there is provided a screen
deck
assembly, comprising: a support deck; a screen including a flexible molded
polyurethane body
having substantially parallel side edge portions at opposite ends of the body,
a lower edge
portion substantially perpendicular to the side edge portions, an upper edge
portion
substantially perpendicular to the side edge portions and opposite the lower
edge portion, an
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upper surface, a lower surface, a first integrally molded grid structure,
wherein the first grid
structure includes first and second members forming screening openings, the
first members
extending between the side edge portions and the second members extending
between the
lower edge portion and the upper edge portion, a second integrally molded grid
structure,
wherein the second grid structure includes third and fourth members, the third
members
substantially parallel and extending transversely between the side edge
portions and having
multiple first members therebetween, the fourth members substantially parallel
and extending
transversely between the lower edge portion and the upper edge portion and
having multiple
second members therebetween, wherein reinforcement members are molded
integrally with at
least one of the first and third members and at least one of the second and
fourth members.
wherein the side edge portions of the screen include attachment arrangements
configured to
secure the screen to the support deck, wherein the side edge portions of the
screen are secured
to the support deck.
In an example embodiment of the present disclosure, there is provided a
screen, comprising: a
flexible molded polyurethane body having substantially parallel side edge
portions at opposite
ends of the body, a lower edge portion transversely disposed between the side
edge portions,
an upper edge portion disposed between the side edge portions and
substantially parallel and
opposite to the lower end portion, an upper surface, a lower surface, a first
integrally molded
grid structure, a second integrally molded grid structure, a third integrally
molded grid
structure and screen openings, wherein the first grid structure includes first
and second
members forming the screening openings, the first members substantially
parallel and
extending transversely between the side edge portions and the second members
substantially
parallel and extending transversely between the lower edge portion and the
upper edge
portion, wherein the second grid structure includes third and fourth members,
the third
members substantially parallel and extending transversely between the side
edge portions and
having multiple first members therebetween, the fourth members substantially
parallel and
extending transversely between the lower edge portion and the upper edge
portion and having
multiple second members therebetween, wherein the third grid structure
includes fifth and
sixth members, the fifth members substantially parallel and extending
transversely between
the side edge portions and having multiple third members therebetween, the
sixth members
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substantially parallel and extending transversely between the lower edge
portion and the upper
edge portion and having multiple fourth members therebetween, wherein
reinforcement
members are molded integrally with at least one of the first, third, and fifth
members and at
least one of the second, fourth, and sixth members, wherein the side edge
portions include
attachment arrangements configured to secure the screen to a structural
member.
In an example embodiment of the present disclosure, there is provided a
screen, comprising: a
flexible molded polyurethane body having substantially parallel side edge
portions at opposite
ends of the body, a lower edge portion substantially perpendicular to the side
edge portions,
an upper edge portion substantially perpendicular to the side edge portions
and opposite the
lower edge portion, an upper surface, a lower surface, a first integrally
molded grid structure,
wherein the first grid structure includes first and second members forming
screening
openings, the first members extending between the side edge portions and the
second
members extending between the lower edge portion and the upper edge portion, a
second
integrally molded grid structure, wherein the second grid structure includes
third and fourth
members, the third members substantially parallel and extending transversely
between the
side edge portions and having multiple first members therebetween, the fourth
members
substantially parallel and extending transversely between the lower edge
portion and the upper
edge portion and having multiple second members therebetween, wherein
reinforcement
members are molded integrally with at least one of the first and third members
and at least one
of the second and fourth members, wherein the side edge portions include
attachment
arrangements configured to secure the screen to a structural member.
In an example embodiment of the present disclosure, there is provided a method
for separating
materials, comprising: installing a screen deck assembly in an attrition
screening device,
wherein the screen deck assembly includes a support deck and a first screen,
second screen,
and third screen, each screen including a flexible molded polyurethane body
having
substantially parallel side edge portions at opposite ends of the body, a
lower edge portion
substantially perpendicular to the side edge portions, an upper edge portion
substantially
perpendicular to the side edge portions and opposite the lower edge portion,
an upper surface,
a lower surface, a first integrally molded grid structure, wherein the first
grid structure
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includes first and second members forming screening openings, the first
members extending
between the side edge portions and the second members extending between the
lower edge
portion and the upper edge portion, a second integrally molded grid structure,
wherein the
second grid structure includes third and fourth members, the third members
substantially
parallel and extending transversely between the side edge portions and having
multiple first
members therebetween, the fourth members substantially parallel and extending
transversely
between the lower edge portion and the upper edge portion and having multiple
second
members therebetween; wherein reinforcement members are molded integrally with
at least
one of the first and third members and at least one of the second and fourth
members, wherein
the side edge portions of each of the first, second, and third screens include
attachment
arrangements configured to secure the screens to the support deck, wherein the
side edge
portions of the first, second, and third screens are secured to the support
deck; and sifting the
materials using the screen deck assembly.
In an example embodiment of the present disclosure, there is provided a system
for separating
materials comprising: an attrition screening device; a screen deck assembly
installed in the
attrition screening device for separating the materials, the screen deck
assembly including a
support deck and a first screen, second screen, and third screen, each screen
including a
flexible molded polyurethane body having substantially parallel side edge
portions at opposite
ends of the body, a lower edge portion substantially perpendicular to the side
edge portions,
an upper edge portion substantially perpendicular to the side edge portions
and opposite the
lower edge portion, an upper surface, a lower surface, a first integrally
molded grid structure,
wherein the first grid structure includes first and second members forming
screening
openings, the first members extending between the side edge portions and the
second
members extending between the lower edge portion and the upper edge portion, a
second
integrally molded grid structure, wherein the second grid structure includes
third and fourth
members, the third members substantially parallel and extending transversely
between the
side edge portions and having multiple first members therebetween, the fourth
members
substantially parallel and extending transversely between the lower edge
portion and the upper
edge portion and having multiple second members therebetween; wherein
reinforcement
members are molded integrally with at least one of the first and third members
and at least one
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of the second and fourth members, wherein the side edge portions of each of
the first, second,
and third screens include attachment arrangements configured to secure the
screens to the
support deck, wherein the side edge portions of the first, second, and third
screens are secured
to the support deck.
Example embodiments of the present invention are described in more detail
below with
reference to the appended Figures.
BRIEF DESCRIPTION OF TIIE DRAWINGS
FIG.1 is a fragmentary plan view of a vibratory screen according to an
exemplary
embodiment of the present invention;
FIG. 1A is a top isometric view of the screen shown in FIG 1;
FIG. 113 is a bottom isometric view of the screen shown in FIG 1;
FIG. 2 is a fragmentary cross sectional view taken substantially along line 2--
2 of FIG 1;
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FIG. 3 is a fragmentary cross sectional view taken substantially along line 3--
3 of
FIG. 1;
FIG. 3A is an enlarged fragmentary cross sectional view of a portion of the
screen
shown in FIG. 3;
FIG. 4 is a plan view of a portion of the screen shown in FIG. 1;
FIG. 4A is an enlarged plan view of a portion of the screen shown in FIG. 4.
FIG. 5 is a fragmentary cross sectional view taken substantially along line 5--
5 of
FIG. 1;
FIG. 5A is an enlarged fragmentary cross sectional view of a portion of the
screen
shown in FIG. 5;
FIG. 6 is an enlarged fragmentary cross sectional view similar to the view
taken
substantially along line 5--5 of FIG. 5, but showing only a cross section
configuration
of a modified shape of first members having reinforcement members;
FIG. 7 is a view similar to FIG. 6 but showing first members without
reinforcement
members;
FIG. 8 is a fragmentary cross sectional view showing the manner in which the
improved screen of FIG. 1 is mounted in a vibratory screening machine;
FIG. 9 is an enlarged isometric view of a portion of a vibratory screen
according to an
exemplary embodiment of the present invention having reinforcement members
integral with first and second members forming screen openings;
FIG. 10A is a top isometric view of a vibratory screen according to an
exemplary
embodiment of the present invention;
FIG. 10B is a bottom isometric view of the screen shown in FIG. 10A;
FIG. 11A is a top isometric view of view of a vibratory screen according to an
exemplary embodiment of the present invention;
FIG. 11B is a bottom isometric view of the screen shown in FIG. 11A;
FIG. 12 is a top isometric view of a vibratory screen with a portion of the
screen
removed showing reinforcement rods according to an exemplary embodiment of the
present invention;
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FIG. 12A is an enlarged top isometric view of a portion of the screen shown in
FIG.
12.
FIG. 13 is an isometric view of a portion of a vibratory screening machine
having a
vibratory screen installed thereon according to an exemplary embodiment of the
present invention;
FIG. 14 is an isometric view of a portion of a vibratory screening machine
having a
vibratory screen installed thereon according to an exemplary embodiment of the
present invention.
FIG. 15 is a top view of a screen for an attrition screening device, according
to an
exemplary embodiment of the present invention;
FIG. 16 illustrates several fragmentary cross sectional views of portions of
the screen
shown in FIG. 15;
FIG. 16A is a fragmentary cross sectional view taken substantially along
Section A-A
of FIG. 15;
FIG. 16B is an enlarged fragmentary cross sectional view of a portion of the
screen
shown in FIG. 15;
FIG. 16C is an enlarged fragmentary cross sectional view of a portion of the
screen
shown in FIG. 15;
FIG. 17 is a top isometric view of a screen deck assembly including three
screens and
a support deck, according to an exemplary embodiment of the present invention;
FIG. 17A is an enlarged isometric view of a portion of the screen deck
assembly
shown in FIG. 17;
FIG. 18 is an exploded isometric view of the screen deck assembly shown in
FIG. 17;
FIG. 19 is an end view of a screen deck assembly with attached spring clips,
according to an exemplary embodiment of the present invention;
FIG. 19A is an enlarged end view of the screen deck assembly shown in FIG. 19
with
attached spring clips not mounted to a screen;
FIG. 19B is an enlarged end view of the screen deck assembly shown in FIG. 19
with
attached spring clips mounted to the screen;
FIG. 20 is a top view of a tension strip, according to an exemplary embodiment
of the
present invention.
DETAILED DESCRIPTION
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Like reference characters denote like parts in the several Figures. The
vibratory
screens described herein may be modified as described herein for attachment to
a
frame or support deck for use with an attrition screening device, including
for
example, a sifter, gyratory sifter, grater, or similar machine that may be
configured to
implement motion to the screen such as oscillatory, gyratory, gyratory
reciprocating,
fully gyratory, rotary, planar, or other type of motion or combinations
thereof.
Embodiments and features of the screens discussed herein with regard to
vibratory
screening machines may also be incorporated into screens attached to frames or
support decks for use in attrition screening devices, including for example
sifters,
gyratory sifters, graters, or similar machines.
According to an exemplary embodiment of the present invention, a vibratory
screen
10 includes a body 12 of molded polyurethane having unperforated side edge
portions
14, 16. Side edge portions 14, 16 may each have an upward U-shape and may each
include a cast-in structural member, such as angle 15 shown in FIG. 2. Side
edge
portions 14, 16 may also be formed without cast-in structural members and/or
may
include other structural members. Side edge portions 14, 16 may be formed in a
U-
shape or any other suitable shape for attachment to a vibratory screening
machine. In
an exemplary embodiment, side edge portions 14, 16 may include a formed
member,
e.g., a metal member that is bent to a desired shape, e.g., a U-shape. The
formed
member may be attached to the polyurethane body by heating, pressing,
mechanical,
chemical, molding and/or any other suitable method/arrangement. Referring back
to
the figures, as shown in FIGS. 11A to 11B, angle 15 may form an upward U-
shape.
Angle 15 may extend the entire length of side edge portions 14, 16. Side
edge
portions 14, 16 may be configured for mounting vibratory screen 10 in a
vibratory
screening machine, as is well known.
Body 12 also includes a lower edge portion 18 and an upper edge portion 20
which, in
combination with side edge portions 14, 16, define an outer border of the
screen 10.
In certain embodiments, angle 15 may be included in upper edge portion 20 and
lower
edge portion 18. See, e.g., FIGS. 10A to 10B. In such embodiments, angle 15
may
extend the entire length of upper edge portion 20 and lower edge portion 18.
In
example embodiments, upper edge portion 20 and lower edge portion 18 may be
configured for mounting on a vibratory screen 1010 designed for mounting
screens
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front to back. See, e.g., FIG. 13. Body 12 further includes an upper surface
22 and a
lower surface 24 and includes first members 101 and second members 102 forming
screen openings 26. Body 12 may further include third members 203, fourth
members 204, fifth members 305 and sixth members 306. Body 12 may include
various configurations of third members 203, fourth members 204, fifth members
305
and/or sixth members 306. The third members 203, fourth members 204, fifth
members 305 and/or sixth members 306 may or may not include reinforcement
members 50 and are generally configured to provide support to screen openings
26
formed by first and second members 101, 102. Body 12 may include first members
101 and second members 102 without third members 203, fourth members 204,
fifth
members 305 and/or sixth members 306. The first and/or second members 101, 102
may be configured to include reinforcement members 50. In certain embodiments,
reinforcement rods 1050 may be incorporated into members running parallel to
the
edge portions of the screen having the vibratory machine attachment
arrangements
(e.g., the edges having the U-shaped structural members discussed herein).
See, e.g.,
FIGS. 12 and 12A. Reinforcement rods 1050 provide stability to screen 10 by
preventing the side edge portions, e.g., side edge portions 14, 16 shown in
FIGS. 10A,
10B, 11A, 11B, 12 and 12A, from deforming and/or hourglassing. Reinforcement
rods do not run perpendicular to the edge portions of the screen having the
vibratory
machine attachment arrangements as they are substantially rigid, provided for
structural support and would generally restrict significant movement or
deflection of
the screen assembly when a force is applied to the edge portions that
interface the
vibratory screening machine tensioning members. In an exemplary embodiment,
reinforcement rods 1050 may be integrated (including by molding integrally)
with
fourth members 204 and/or sixth members 306. Reinforcement rods 1050 may be
made of plastic, metal, polymer or any other suitable material with the
necessary
structural properties.
First and second members 101, 102 form a first integrally molded grid
structure 100
that defines screen openings 26. Third and fourth members 203, 204 may form a
second integrally molded grid structure 200. Reinforcement rods 1050 may be
integrally molded into fourth members 204. Fifth and sixth members may form a
third integrally molded grid structure 300. Reinforcement rods 1050 may be
integrally molded into sixth members 306. As shown in the exemplary embodiment
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depicted in FIGS. 1, 2, 3, 4 and 5, grid structures 200 and 300 include bi-
directional
integrally molded reinforcement members forming support grids within the
members.
Because of the properties of the reinforcement members 50, further discussed
herein,
and their configuration into a bi-directional grid structure, the members in
which the
.. reinforcement members 50 are embedded have a relatively small size and
provide for
increased open screening area. The grid structures provide screen strength,
support
for openings 26 during vibratory loading and significantly increase open
screening
area. Although second and third grid structures are discussed herein, fewer or
additional grid structures may be provided.
First members 101 may be substantially parallel to each other and extend
transversely
between side edge portions 14, 16. The second members 102 may be substantially
parallel to each other and extend transversely between the lower edge portion
18 and
the upper edge portion 20. Second members 102 may have a thickness greater
than
the first members to provide additional structural support to screen openings
26.
First members 101 and/or second members 102 may include reinforcement members
50 and may or may not be supported by additional support members or support
grid
structures. See, e.g., FIGS. 6 and 9. As shown in FIG. 9, body 12 has first
and
second members 101, 102 with bi-directional reinforcement members 50 molded
integrally therewith. The first members include reinforcement members molded
integrally therewith, the reinforcement members having a thickness in the
range of
about .006 inches to about .015 inches. The second members include
reinforcement
members molded integrally therewith, the reinforcement members having a
thickness
in the range of about .015 inches to about .040 inches. Such configurations
may be
beneficial for screening applications requiring screens with larger screen
openings.
In certain embodiments, reinforcement rods 1050 may be incorporated into at
least
one of the fourth and sixth members, 204 and 306 respectively and run from
edges 14
to 16. See., e.g. FIGS. 12 and 12A. Reinforcement rods 1050 provide stability
and
prevent hourglassing or other deformation of the screen along the edges of the
screen
without the U-shape channels, i.e., edges 14 and 16. These embodiments may
incorporate reinforcement members 50 in first, second, third, fourth, fifth
and/or sixth
members 101, 102, 203, 204, 305, 306. Reinforcement members 50 may be
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incorporated into all or a portion of first, second, third, fourth, fifth
and/or sixth
members 101, 102, 203, 204, 305, 306. Reinforcement members 50 provide screen
properties as discussed herein.
As shown in FIG. 4, the screen openings 26 are elongated with a greater length
dimension along sides and between ends thereof than width dimensions between
the
sides and their length dimensions extending in a direction transverse to the
side edge
portions 14, 16. Screen openings 26 may be about .044 mm to about 4 mm in
width
(i.e., between the inner surfaces of adjacent first members 101) and about
.044 mm to
about 60 mm in length (i.e., between inner surfaces of adjacent second members
102).
Screen openings 26 may have a variety of different shapes. For example, the
screen
openings 26 may have a rectangular shape, a square shape, circular shape
and/or any
other shape that may be formed by the first and second members 101, 102. The
overall dimensions of screen 10 may be about 1.2 meters times 1.6 meters, or
any
other desired size. All of the dimensions set forth herein are by way of
example and
not of limitation.
Screen openings 26 may diverge downwardly between the upper surface 22 and the
lower surface 24 and the first members 101 may be substantially in the shape
of
inverted trapezoids. See, e.g., Figures 6 and 7. This general shape of the
first
members 101 prevents blinding in screens 10. As shown in Figure 6, first
members
101 include reinforcement members 50. As shown in Figure 7, first members 101
do
not include reinforcement members 50.
Screens with the various screen opening sizes and support configurations
described
herein have a relatively large open screening areas. Open screening areas may
range,
for example, from between about 40 percent to about 46 percent. As further
discussed
herein, the relatively large open screening areas may be obtained through the
placement of bi-directional reinforcement members 50 in cross members (e.g.,
members 203, 204) as described in the various embodiments herein. The
reinforcement members significantly decrease the size of both of the bi-
directional
support cross members and allow for a thinner screen members, 101, 102 forming
the
screen openings 26. The grid work of support members and reinforcement members
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provide for a structurally sound screen that maintains the necessary screen
openings
during vibratory operation.
Third and fourth members 203, 204 may have a thickness greater than the first
and
second members 101, 102. The greater thickness may provide additional
structural
support to first and second members 101, 102. The third members 203 may be
substantially parallel and extend transversely between the side edge portions
14, 16
and may have multiple first members 101 therebetween. The fourth members 204
may be substantially parallel and extend transversely between the lower edge
portion
18 and the upper edge portion 20 and having multiple second members 102
therebetween. Fourth members 204 may have reinforcement rods 1050 integrally
molded therein. Reinforcement members 50 may be molded integrally with the
third
and fourth members 203, 204. See, e.g., FIGS. 3A, 5A. Third and fourth members
203, 204 may be configured to have a minimal thickness through inclusion of
reinforcement members 50, while providing the necessary structural support to
maintain the screen openings 26 formed by first and second members 101, 102
during
vibratory screening applications. The bi-direction support system provided by
reinforced third and fourth members 203, 204 greatly reduces the thickness of
the
support members and provides for increased open screening area and overall
screen
efficiencies. Incorporation of reinforcement rods 1050 into fourth members 204
may
adds stability to screen 10 and prevents hourglassing, i.e., deflection
inwardly of side
edges 14, 16 to give the screen a general hourglass type shape.
Fifth members 305 and sixth members 306 may be included in body 12. Fifth and
sixth members may have a thickness greater than the third and fourth members
and
may have a portion 310 extending downwardly away from the lower surface of the
body. The greater thickness and portion extending downwardly may to provide
additional structural support to first and second members 101, 102. The sixth
members 306 may include a portion 320 extending upwardly away from the upper
surface of the body. Portion 320 may be substantially triangular in cross-
section with
apexes projecting away from the upper surface 22 of body 12. Sixth members 306
are
shown in FIG. 2 with portion 320 extending upwardly away from the upper
surface of
body 12 and acting as flow guides. Sixth members 306 may have reinforcement
rods
1050 integrally molded therein. The fifth members 305 may be substantially
parallel
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and extending transversely between the side edge portions 14, 16 and have
multiple
third members 203 therebetween. The sixth members 306 may be substantially
parallel and extending transversely between the lower edge portion 18 and the
upper
edge portion 20 and have multiple fourth members 204 therebetween.
Reinforcement
members 50 may be molded integrally with fifth and sixth members 305, 306.
Fifth
and sixth members 305, 306 may be provided for additional support to screen
openings 26 and may be configured to have a minimal thickness through
inclusion of
reinforcement members 50, while providing the necessary structural support to
maintain screen openings 26 during vibratory screening applications. The bi-
direction
support system provided by reinforced fifth and sixth members 305, 306 greatly
reduces the thickness of the support members and provides for increased open
screening area and overall screen efficiencies. Incorporation of reinforcement
rods
1050 into sixth members 306 adds stability to screen 10 and prevents
hourglassing.
FIG. 1A shows an exemplary embodiment of the present inventions having first
and
second members 101, 102 forming screen openings 26 and members 203, 204
forming a support grid structure for openings 26. As shown in FIG. 1A, screen
10
does not include fifth and sixth members 305, 306. FIGS. 12 and 12A show
another
exemplary embodiment of the present invention having reinforcement rods 1050
integrally molded therein. As shown in FIGS. 12 and 12A, reinforcement rods
1050
are integrally molded into fourth members 204. Reinforcement rods 1050 may
also
be integrally molded into sixth members 306 or other members running parallel
to
members 204 and 306.
In use, the vibratory screen 10 is mounted on a vibratory screening machine 30
(FIG.
8) in the well known manner. More specifically, it is mounted on the screen
deck bed
31 which is mounted on the frame (not shown) of the machine. The screen deck
bed
31 includes spaced substantially parallel frame members 32 secured to each
other by
spaced substantially parallel cross frame members (not shown). Extending
transversely between the cross frame members are a plurality of substantially
parallel
stringers 33 which mount channel rubbers 34. Mounted on parallel frame members
32
are channel-shaped draw bars 35 having lower portions 36 which are received
within
side edge portions 14, 16. Draw bolts 37 draw bars 35 apart to thereby tension
vibratory screen 10 with the required force. The foregoing type of screen deck
bed is
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well known in the art. Screen 10 may be mounted to other vibratory screening
machines and side edge portions 14, 16 may be configured in other shapes to
accommodate different vibratory screening machines.
The embodiment shown in FIG. 13 is mounted front to back on vibratory
screening
machine 1010. In this embodiment, angle 15 is included in upper edge 20 and
lower
edge 18 and is below top surface 22. This embodiment has tension applied from
underneath the screen rather than above and the tension is applied from front
to back.
FIG. 14 shows an embodiment having angle 15 included in side edges 18, 20.
This
embodiment also has tension applied from above the screen and from side to
side.
Reinforcement members 50 as described herein may be an aramid fiber (or
individual
filaments thereof), a naturally occurring fiber or others material having
relatively
large tensile strengths with relatively small cross sectional areas. When an
aramid
fiber is used as reinforcement fiber 50 it may be aramid fibers that are
commercially
obtainable under the trademark KEVLAR of the DuPont Company and further
identified by the designation KEVLAR 29. The reinforcement members 50 may also
be at least one of aramid fibers that are commercially obtainable under the
trademarks
TWARON, SULFRON, TEIJINCONEX, and TECHNORA of the Teijin Company.
In addition, the aramid fibers may be twisted or woven multistrand so that
they act as
nature of wicks to absorb the polyurethane which is molded around them to
thereby
provide an extremely good bond therewith. The twisted or a woven multistrand
fibers may be about 55 denier to about 2840 denier, preferably approximately
1500
denier. The flexibility of the aramid fibers provides a flexible reinforcement
system
for the molded polyurethane which is able to return to its original molded
shape after
the necessary bending and flexing that occurs during handling and installation
into the
vibratory frame member 32. Furthermore, flexible aramid fibers permit the
flexible
polyurethane screen to be flexed without harm into an arcuate condition and
tensioned
as shown in FIGS. 8, 13 and 14. Reinforcement members 50 may be tensioned
before
polyurethane is molded around them. Various configurations of reinforcement
members 50 may be provided in any one of the first, second, third, fourth,
fifth and
sixth members 101, 102, 203, 204, 305, 306. Each member may include zero, one
or
more reinforcement members 50 and the reinforcement members 50 may be of
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different sizes and materials. Reinforcement members 50 may be located in the
bottom halves of the members so as not to be exposed relatively early as the
upper
surface of the screen wears.
During operation, first members 101 will vibrate to enhance the screening
action. In
this regard, it is to be noted that because first members 101 are flexible and
relatively
thin they will provide a relatively high amplitude of desirable vibration. The
reason
the first members 101 can be made relatively thin, creating screen openings
described
herein, is because of a support framework of bi-directional support members
and
reinforcement members, as described herein, having relatively large tensile
strengths
with relatively small cross sectional areas. The making of the support members
and
the first members 101 relatively thin results in the screen having a greater
percentage
of open area, which, in turn, increases its capacity.
All of the dimensions set forth herein are by way of example and not of
limitation.
Figure 15 shows a top view of a screen 1010, which is configured for
attachment to a
support deck 1011 and for use in an attrition screening device such as a
sifter. The
screen includes a body of molded polyurethane having side edge portions 1014,
1016.
The screen 1010 also includes a lower edge portion 1018 and an upper edge
portion
1020 which, in combination with side edge portions 1014, 1016, define an outer
border of the screen 1010. In some embodiments, side edge portions 1014, 1016
may
include multiple grommets 1027 spaced evenly from each other. See, e.g., FIGS.
15
and 16B. Side edge portions 1014, 1016 with grommets 1027 may be configured
for
mounting screens 1010 to a support deck 1011 in an attrition screening device
such as
a sifter using a plurality of clips 1060 See, e.g., FIG. 17 and FIG. 17A. The
grommets
1027 are shown as oval shaped, but may also be circular, rectangular, or any
other
shape suitable for securing the screens 1010 to the support deck 1011. In an
exemplary embodiment, the multiple grommets 1027 are spaced evenly from each
other. In an alternative embodiment, the multiple grommets 1027 may be spaced
at
varying distances from each other. Side edge portions 1014, 1016 may each
include a
tension strip 1025, such as shown in FIGS. 16A and 20. The tension strip 1025
may
be a formed member, e.g., a metal member or other suitable structural member
that
may extend the entire length of side edge portions 1014, 1016, or may extend
only a
portion of the length of the side edge portions 1014, 1016. The tension strip
1025 may
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be secured to or within the polyurethane body of the screen 1010. The tension
strip
1025 may be a cast-in tension strip 1025 and formed inside the side edge
portions
1014, 1016 of the screen 1010 by heating, pressing, mechanical, chemical,
molding
and/or any other suitable method/arrangement.
In some embodiments, side edge portions 1014, 1016 may include multiple
apertures
1028 spaced evenly from each other. See, e.g., FIGS. 15, 16C, and 20. Side
edge
portions 1014, 1016 with apertures 1028 may be configured to be filled up with
polyurethane to hold or suspend the cast-in tension strip 1025 in place within
the side
edge portions 1014, 1016 of the screen 1010. The apertures 1028 are shown as
circular shaped, but may also be oval, rectangular, or any other shape
suitable for
holding or suspending the cast-in tension strip 1025 in place within the side
edge
portions 1014, 1016 of the screen 1010. In an exemplary embodiment, the
multiple
apertures 1028 are spaced evenly from each other. In an alternative
embodiment, the
multiple apertures 1028 may be spaced at varying distances from each other. In
an
exemplary embodiment, as shown in FIG. 20, the cast-in tension strip 1025 may
be
formed with openings forming the grommets 1027 or apertures 1028 on the side
edge
portions 1014, 1016. See FIG. 20. The cast-in tension strip 25 is configured
to
distribute loads evenly across the screen 1010. Side edge portions 1014, 1016
may
also be formed without tension strips 1025 and/or may include other structural
members. FIG. 16C is an enlarged fragmentary cross sectional view of a portion
of
the screen 1010 showing both the side edge portion 1014 as well as the cast-in
tension
strip 1025 located inside the side edge portion 1014.
Referring now to FIG. 17 and FIG. 18, an embodiment of a screen deck assembly
1013 for an attrition screening device such as a sifter is shown. FIG. 17
shows a top
isometric view of screen deck assembly 1013 including three screen sections
and a
support deck 1011. FIG. 18 shows an exploded isometric view of the same screen
deck assembly 1013. The support deck 1011 may be configured in several ways.
In an
exemplary embodiment, the support deck 1011 may be a single unit with three
equally-sized square or rectangular shaped screen sections adjacent to each
other,
each screen section configured for attachment of screens 1010. In an
alternative
embodiment, the support deck 1011 may have more or less screen sections
configured
for attachment of screens 1010, and may be provided in various shapes for use
in
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various screening machines used for separation of materials. The support deck
1011
may have a plurality of parallel support members or cross-members extending
across
each screen section in a direction substantially parallel to the side edge
portions 1014,
1016. In an alternative embodiment, the support deck 1011 may have a plurality
of
parallel support members or cross-members extending across each screen section
in a
direction substantially perpendicular to the side edge portions 1014, 1016. In
an
exemplary embodiment, each screen section of the support deck 1011 may have
three
parallel support members or cross-members. In alternative embodiments, each
screen
section of the support deck 1011 may have more or less parallel support
members or
cross-members.
Each screen section of the support deck 1011 may be configured for attachment
of
one screen 1010, respectively. In an exemplary embodiment, each screen 1010
may
be rectangular-shaped. In an alternative embodiment, each screen 1010 may be
square-shaped or any other shape suitable for attachment to a support deck
1011. This
configuration allows for easy replacement of one screen 1010 from a screen
section of
the screen deck assembly 1013 without replacing all three screens 1010 at
once. In an
embodiment, the screens 10 may be placed next to each other so that some
overlap
exists between the screens 1010. To accomplish this overlap between the
screens
1010, a first screen 1010 may include an overlap sealing member 1019 attached
to
and extending away from an outer border of the lower edge portion 1018 of the
screen, as shown in FIGS. 17 and 18. The overlap sealing member 1019 may then
be
attached to the upper edge portion 1020 of an adjacent second screen 1010
placed
next to the first screen 1010 with the attached overlap sealing member 1019.
This
overlap sealing member 1019 may be configured to assist in placing the screens
1010
next to each other in such a manner as to allow the first screen 1010 to
overlap the
adjacent second screen 1010 and form a seal thereto or otherwise secure itself
thereto.
In an embodiment, only one screen may contain an overlap sealing member 1019
such
that two out of three screens 1010 overlap with each other. In an alternative
embodiment, two screens 1010 may contain overlap sealing members 1019 such
that
all three screens 1010 overlap with each other. The overlap sealing members
1019
may be attached to the screens 1010 or formed as part of the screens 1010.
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Each screen 1010 is mounted to and/or tensioned across the support deck 1011
using a
plurality of spring clips 1060. See, e.g., FIG. 17A. As shown in FIG. 19, the
spring
clips 1060 are generally U-shaped with a hook-shaped portion 1061 projecting
from
one end thereof that is seated within a similarly shaped flange 1062 extending
around
the upper edge of the support deck 1011. A tang 1063 extends from the opposite
end
of the U-shaped spring clip 1060. See FIGS. 19A and 19B. The tang 1063 may be
inserted through the grommet 1027 at the perimeter of the screen 1010 to mount
the
screen 1010 onto the support deck 1011. See FIG. 19B. The end of the U-shaped
spring clip 1060 may then be slightly compressed together to thereby tension
the
screen 1010 on the support deck 1011. Although spring clips 1060 are disclosed
in
this particular embodiment, other methods may also be used for attaching the
screens
1010 to the support deck 1011, including but not limited to fasteners,
adhesives,
drawbars, and/or other mechanical attachment systems and combinations thereof,
including securing the screen 1010 on one side to the support deck 1011 and
tensioning the opposing side of the screen 1010 with a fastener, including a
removable
spring clip 1060.
Once the screens 1010 are secured to the support deck 1011, the screen deck
assembly
1013 is then inserted into an attrition screening device such as a sifter,
disclosed in
U.S. Patent Nos. 6,070,736, 8,113,358, 8,522,981, and U.S. Patent Pub. No.
2011/0036759, in the direction shown by arrow A in FIG. 17. In an exemplary
embodiment of the screen deck assembly 1013 including three screens 1010, the
screen deck assembly 1013 is inserted into the attrition screening device with
the
upper edge portion 1020 of a first screen 1010 being inserted first, followed
by a
second screen 1010 adjacent to the first screen 1010, and ending with the
lower edge
portion 1018 of a third screen 1010. Other orientations and configurations may
be
utilized, depending on the particular attrition screening device being
utilized, for
securing screen 1010 or screens 1010 to a support deck 1011 and inserting it
into the
attrition screening device.
In an exemplary embodiment, the screens 1010 for use in attrition screening
devices
such as sifters may include features disclosed and described herein for
screens 10
used in vibratory screening machines. See, e.g., FIGS. 4, 4A, 5, 6, 7, and 9.
For
example, screens 1010 may include features described with regard to screens 10
such
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as the materials, shapes and/or configurations of the upper surface, lower
surface, first
members, second members, third members, fourth members, fifth members, sixth
members, reinforcement members, and reinforcement rods. The third members,
fourth members, fifth members and/or sixth members may or may not include
reinforcement members and are generally configured to provide support to
screen
openings formed by first and second members. The screen 1010 may include first
members and second members without third members, fourth members, fifth
members and/or sixth members. The first and/or second members may be
configured
to include reinforcement members. In certain embodiments, reinforcement rods
may
be incorporated into members running parallel to the edge portions 1014, 1016
of the
screen 1010. Reinforcement rods provide stability to screen 1010 by preventing
unwanted deformations and/or hourglassing. In an
exemplary embodiment,
reinforcement rods may be integrated (including by molding integrally) with
fourth
members and/or sixth members. Reinforcement rods may be made of plastic,
metal,
polymer or any other suitable material with the necessary structural
properties. In an
embodiment of the present invention, screen 1010 may be pre-tensioned with
structural members, which may be internal or external and then clamped or
otherwise
secured to a member of a frame or support deck 1011.
First and second members may form a first integrally molded grid structure
that
defines screen openings in the screen 1010. Third and fourth members may form
a
second integrally molded grid structure. Reinforcement rods may be integrally
molded into fourth members. Fifth and sixth members may form a third
integrally
molded grid structure. Reinforcement rods may be integrally molded into sixth
members. As shown in the exemplary embodiment depicted in FIGS. 1, 2, 3, 4 5,
and
15, grid structures include bi-directional integrally molded reinforcement
members
forming support grids within the members. Although second and third grid
structures
are discussed herein, fewer or additional grid structures may be provided
depending
on the overall size and shape of the screen 1010 and support needed for the
screen
1010.
First members may be substantially parallel to each other and extend
transversely
between side edge portions 1014, 1016. In this embodiment, the first members
run
perpendicular to the side edge portions 1014, 1016. The second members may be
substantially parallel to each other and extend transversely between the lower
edge
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portion 1018 and the upper edge portion 1020. In this embodiment, the second
members run parallel to the side edge portions 1014, 1016. Second members may
have a thickness greater than the first members to provide additional
structural
support to screen openings in the screen 1010. First members and/or second
members
may include reinforcement members and may or may not be supported by
additional
support members or support grid structures.
In certain embodiments, reinforcement rods may be incorporated into at least
one of
the fourth and sixth members, respectively, and run from edges 1014 to 1016
(or vice-
versa). Reinforcement rods provide stability and prevent hourglassing or other
deformation of the screen along the side edge portions 1014, 1016 of the
screen 1010.
These embodiments may incorporate reinforcement members in first, second,
third,
fourth, fifth and/or sixth members. Reinforcement members may be incorporated
into
all or a portion of first, second, third, fourth, fifth and/or sixth members.
Third and fourth members may have a thickness greater than the first and
second
members. The greater thickness may provide additional structural support to
first and
second members. The third members may be substantially parallel and extend
transversely between the side edge portions 1014, 1016 and may have multiple
first
members therebetween. In this embodiment, the third members run perpendicular
to
the side edge portions 1014, 1016. The fourth members may be substantially
parallel
and extend transversely between the lower edge portion 1018 and the upper edge
portion 1020 and may have multiple second members therebetween. In this
embodiment, the fourth members run parallel to the side edge portions 1014,
1016.
Fourth members may have reinforcement rods integrally molded therein.
Reinforcement members may be molded integrally with the third and fourth
members.
Third and fourth members may be configured to have a minimal thickness through
inclusion of reinforcement members, while providing the necessary structural
support
to maintain the screen openings in the screen 1010 formed by first and second
.. members during sifter screening applications. The bi-direction support
system
provided by reinforced third and fourth members greatly reduces the thickness
of the
support members and provides for increased open screening area and overall
screen
efficiencies. Incorporation of reinforcement rods into fourth members may add
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stability to screen 1010 and prevents unwanted deformations and/or
hourglassing of
screen 1010.
Fifth members and sixth members may be included in the screens 1010. Fifth and
sixth members may have a thickness greater than the third and fourth members
and
may have a portion extending downwardly away from the lower surface of the
screen
1010. The greater thickness and portion extending downwardly may to provide
additional structural support to first and second members. Sixth members may
have
reinforcement rods integrally molded therein. The fifth
members may be
substantially parallel and extend transversely between the side edge portions
1014,
1016 and have multiple third members therebetween. In this embodiment, the
fifth
members run perpendicular to the side edge portions 1014, 1016. The sixth
members
may be substantially parallel and extend transversely between the lower edge
portion
1018 and the upper edge portion 1020 and have multiple fourth members
therebetween. In this embodiment, the sixth members run parallel to the side
edge
portions 1014, 1016. Reinforcement members may be molded integrally with fifth
and
sixth members. Fifth and sixth members may be provided for additional support
to
screen openings of the screen 1010 and may be configured to have a minimal
thickness through inclusion of reinforcement members, while providing the
necessary
structural support to maintain screen openings of the screen 1010 during
sifter
screening applications.
According to an exemplary embodiment of the present invention, a vibratory
screen
10 includes a flexible molded polyurethane body 12 having substantially
parallel side
edge portions 14, 16 at opposite ends of body 12, a lower edge portion 18
substantially perpendicular to the side edge portions 14, 16, an upper edge
portion 20
substantially perpendicular to the side edge portions 14, 16 and opposite the
lower
edge portion 18, an upper surface 22, a lower surface 24, first and second
members
101, 102 forming screening openings 26, the first members 101 extending
between
the side edge portions 14, 16 and the second members 102 extending between the
lower edge portion 18 and the upper edge portion 20. The body may also include
third and fourth members 203, 204. Third and fourth members 203 and 204 may
have
a thickness greater than the first and second members 101, 102. Third members
203
are substantially parallel and extend transversely between the side edge
portions 14,
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16 and have multiple first members 101 therebetween. Fourth members 204 are
substantially parallel and extend transversely between the lower edge portion
18 and
the upper edge portion 20 and have multiple second members 102 therebetween.
Reinforcement members 50 may be molded integrally with the third and/or fourth
members 203, 204. Reinforcement rods 1050 may be molded integrally with fourth
members 204. The body also includes fifth and sixth members 305, 306. Fifth
members 305 are substantially parallel and extending transversely between the
side
edge portions 14, 16. Sixth members 306 are substantially parallel and
extending
transversely between the lower edge portion 18 and the upper edge portion 20.
The
fifth and sixth members have a thickness greater than the third and fourth
members
and include reinforcement members 50 molded integrally therewith.
Reinforcement
rods 1050 may be molded integrally with the sixth members 306. Vibratory
screens
according to this configuration may have open screening areas greater than
forty
percent and mesh sizes ranging from approximate .375 mesh to approximately 400
mesh. By way of example, screens tested having the aforementioned
configuration
include a 43 mesh size screen, a 140 mesh size screen and a 210 mesh size
screen.
Each of these screens had open screening areas of approximately 40 percent to
approximately 46 percent. Such large screening areas for such fine mesh sizes
are
achieve through the relatively strong and thin grid framework created by the
third,
fourth, fifth and sixth members, 203, 204, 305, 306 and reinforcement members
molded integrally therewith. In the aforementioned exemplary embodiment and
examples, the size of each grid unit formed by the intersection of the third
and fourth
members, 203 and 204 is approximately 1" by 1". Generally, grid units may be
larger
for screens with larger screen openings and grid units are smaller for screens
with
smaller screen openings. This principle may be generally applicable for each
example
embodiment discussed herein. Grid units may also have a generally rectangular
shape
or any other suitable shape for supporting the screen openings.
According to an exemplary embodiment of the present invention, a screen deck
assembly 1013 for an attrition screening device such as a sifter includes the
above
described polyurethane screens 1010, as well as a support deck 1011. In an
exemplary
embodiment, a first screen 1010, second screen 1010, and third screen 1010 may
be
attached to a single support deck 1011. In an alternative embodiment,
additional or
fewer screens 1010 may be included. The side edge portions 1014, 1016 of each
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the first, second, and third screens 1010 may include grommets configured to
mount
the screens 1010 onto the support deck 1011. In an embodiment, each of the
first,
second, and third screens 1010 may be mounted onto the support deck 1011 and
tensioned using a plurality of spring clips 1060 and/or cast-in tension strips
1025. The
cast-in tension strips 1025 may be configured to distribute loads evenly
across each
screen 1010 and provide additional structural support for the grommets 1027 on
the
side edge portions 1014, 1016 of each of the first, second, and third screens
1010. In
an exemplary embodiment, each of the first, second, and third screens 1010 may
also
include a first overlap sealing member 1019 and second overlap sealing member
1019
both attached to and extending away from an outer border of the lower edge
portions
1018 of the each of the first and second screens 1010, the first overlap
sealing
member 1019 configured to overlap a portion of the second screen 1010, and the
second overlap sealing member 1019 configured to overlap a portion of the
third
screen 1019, such that seals are formed between the screens 1010.
According to an exemplary embodiment of the present invention, a method of
making
a vibratory screen, includes. creating a mold configured to fabricate the
vibratory
screen, the vibratory screening having a flexible molded polyurethane body;
installing
reinforcement members in the mold, the reinforcement members configured to be
molded integrally with the body; installing reinforcement rods in the mold,
the
reinforcement rods configured to be molded integrally with the body, filling
the mold
with polyurethane; and forming the vibratory screen that has: substantially
parallel
side edge portions at opposite ends of the body, a lower edge portion
substantially
perpendicular to the side edge portions, an upper edge portion substantially
perpendicular to the side edge portions and opposite the lower edge portion,
an upper
surface, a lower surface, first and second members forming screening openings,
the
first members extending between the side edge portions and the second members
extending between the lower edge portion and the upper edge portion, third and
fourth
members, the reinforcement rods molded integrally with at fourth members, the
third
members substantially parallel and extending transversely between the side
edge
portions and having multiple first members therebetween, the fourth members
substantially parallel and extending transversely between the lower edge
portion and
the upper edge portion and having multiple second members therebetween,
reinforcement members molded integrally with at least one of the first and
second
members.
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According to an exemplary embodiment of the present invention, a system for
screening materials includes an attrition screening device such as a sifter
and a screen
deck assembly including a support deck 1011 and the above described
polyurethane
screens 1010 secured thereto. In an exemplary embodiment, a first screen 1010,
second screen 1010, and third screen 1010 may be attached to a single support
deck
1011. In an alternative embodiment, additional or fewer screens 1010 may be
included. The side edge portions 1014, 1016 of each of the first, second, and
third
screens 1010 may include grommets configured to mount the screens 1010 onto
the
support deck 1011. In an embodiment, each of the first, second, and third
screens
1010 may be mounted onto the support deck 1011 and tensioned using a plurality
of
spring clips 1060 and/or cast-in tension strips 1025. The cast-in tension
strips 1025
may be configured to distribute loads evenly across each screen 1010. In an
exemplary embodiment, each of the first, second, and third screens 1010 may
also
include a first overlap sealing member 1019 and second overlap sealing member
1019
both attached to and extending away from an outer border of the lower edge
portions
1018 of the each of the first and second screens 1010, the first overlap
sealing
member 1019 configured to overlap a portion of the second screen 1010, and the
second overlap sealing member 1019 configured to overlap a portion of the
third
screen 1019, such that seals are formed between the screens 1010. The screen
deck
assembly 1013 may be inserted into the attrition screening device for
screening.
Screens 1010 and screen deck assembly 1013 may include the various features
described herein.
According to an exemplary embodiment of the present invention, a method of
installing the above described screen deck assembly 1013 in an attrition
screening
device such as a sifter includes mounting a screen 1010 onto a support deck
1011
such that it forms a screen deck assembly 1013, inserting the screen deck
assembly
1013 into the attrition screening device, and sifting a material. In an
embodiment, the
screen 1010 is mounted to the support deck 1011 and tensioned using a
plurality of
spring clips 1060 and/or cast-in tension strips 1025. Screens 1010 and screen
deck
assembly 1013 may include the various features described herein.
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Now, these urethane screens are longer lasting, simpler in design, more easily
removable and replaceable, lighter, and provide smaller, more consistent and
accurate
opening sizes than existing screens used in attrition screening devices such
as sifters.
The urethane screens do not have to be replaced for at least two months, as
opposed to
twice a week for current screens being used in attrition screening devices
such as
sifters. The non-blinding urethane configuration of the screens, including
tapered
screening openings, helps maintain a consistent feed rate over an extended
period of
operation of the attrition screening devices. Further, the superior properties
exhibited
by these screens eliminate the need for ball trays or ball boxes that are
currently used
in attrition screening devices such as sifters using wire screens to help de-
blind the
woven wire cloth. The elimination of the need for these ball trays or boxes
has the
additional benefit of reducing and/or eliminating the emission of hazardous
airborne
particles during the screening process, thus improving the health and safety
of those
operating these machines.
While preferred embodiments of the present invention have been disclosed, it
will be
appreciated that it is not limited thereto but may be otherwise embodied
within the
scope of the following claims.
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