Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02240693 1998-06-15
WO 97128906 PCTlGB97/00385
SCREEN FOR VIBRATING SEPARATOR
The invention relates to a screen for use in a
f
shale shaker.
Vibrating screens have been employed for many years
to separate particles in,a wide array of industrial
applications. One common application of vibrating
screens is in drilling operations to separate particles
suspended in drilling fluids. The screens are generally
flat and are mounted generally horizontally on a vibra-
ting mechanism or shaker that imparts either a rapidly
reciprocating linear, elliptical or circular motion to
the screen. Material from which particles are to be
separated is poured onto a back end of the screen,
usually from a pan mounted above the screen. The mater-
ial generally flows toward the front end of the screen.
Large particles unable to move through the screen remain
on top of the screen and move toward the front of the
screen where they are collected. The smaller particles
and fluid flow through the screen and collects in a pan
beneath the screen.
A vibrating screen may be formed from one or more
layers of wire mesh. Wire mesh is generally described
with reference to the diameter of the wires from which
it is woven, the number wires per unit length (called
a
mesh count), and the shape or size of the openings be-
tween wires. Wire mesh comes in various grades.
'Market" grade mesh generally has wires of relative
large diameter. "Mill" grade has comparatively smaller
diameter wires and "bolting cloth" has the smallest
diameter wire. The type of mesh chosen depends on the
application. Smaller diameter wires have less surface
and thus less drag, resulting in greater flow rates.
Smaller diameter wires also result, for a given opening
size, in a larger percentage of open area over the total
area of the screen, thus allowing greater flow rates and
CA 02240693 2005-08-25
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increased capacity. However, screens of bolting cloth
tear more easily than market or mill grade screens,
especially when used in harsh conditions such as
drilling and mining operations. The smaller diameter
wires tend to have less tensile strength and break more
easily, and the finer mesh also tends not to retain its
shape well.
Most meshes suffer from what is termed as "near
sized particle blinding". During vibration, wires
separate enough to allow particles of substantially the
same size or slightly larger than the openings to fall
between the wires and become lodged, thus "blinding" the
openings of the screen and reducing capacity of the
screen. If a particle becomes lodged when the wires are
at a maximum distance apart, it is almost impossible to
dislodge the particle. Sometimes, however, wires will
subsequently separate further to release the lodged
particle. Unfortunately, some wire mesh, especially
bolting cloth, is tensioned. Tensioning restricts
movement of the wires. Restricting movement assists in
holding the shape of the wire mesh, keeping the size of
the openings consistent to create a more consistent or
finer "cutting point" and reducing abrasion from wires
rubbing against each other. However, restricted
movement of the wires reduces the probability that, once
a near sized particle becomes stuck, the wires will
subsequently separate to allow the particle to pass.
Use of smaller diameter wires, with smaller profiles,
helps to reduce blinding. With a smaller diameter wire,
a particle is less likely to become lodged midway
through the opening.
Multiple layers of mesh may be used to alleviate
blinding. U.S. Patent No. 4,033,865 to Derrick, Jr.,
describes layering two meshes in a manner that results
in at least one wire of the lower of the two meshes
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bisecting each opening in the upper mesh. The openings
in each mesh are at least twice as wide as the diameters
of the wires and the lower mesh has openings the same
sire as or slightly larger than the openings in the
upper mesh. The lower mesh, when held tightly against
the upper mesh, prevents particles from migrating far
enough into an opening in the upper mesh to be trapped.
Some relative movement of the layers also helps to
dislodge particles caught in the upper layer. The two-
layer arrangement has the further benefit of a finer
"cutting point," allowing smaller particles to be se-
parated out. A third 'backing" layer of relatively
coarse, mill grade mesh is often used to carry most of
the load on the screen and to increase the tensile
strength of the screen.
Another problem faced in most applications is the
inevitable tearing of the screen. The problem can be
especially acute in heavy duty applications such as
drilling and mining. A torn screen must be replaced or
2O repaired. To facilitate repair, the screen layers are
bonded to a flat rigid or semi-rigid support panel that
has a pattern of large openings, forming on the screen
a
plurality of small cells of wire mesh. When a tear
occurs in 'the screen, the mesh remaining within the cell
in which the tear occurred is cut out and the cell is
plugged. The capacity of the screen is diminished but
its life is extended. Typically, several cells of a
screen can be repaired before its capacity drops far
enough to require replacement. Unfortunately, bonding
the screen to the support panel further restricts rela-
tive movement of the layers and the wires in each mesh
layer, thus compounding the problem of blinding.
Blinding and tearing of the screens are inevitable,
and thus capacity of the screen continually drops
through its useful life. Although capacity can be
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increased by increasing the total area the screens, the
size of the screen is limited in most applications, such
as on drilling rigs, especially those on offshore
platforms. There has thus been generally a trade-off
between capacity, longevity, repairability and
resistance to blinding of the screens.
According to one aspect of the present invention
there is provided a screen for use in a shale shaker,
which screen comprises:
(a) a support panel formed with a series of alternating
substantially parallel ridges and channels, wherein at
least the top of one of said ridges is substantially
flat and is provided with at least one elongate opening
which is wholly contained within said ridge: and
(b) at least a first layer of mesh bonded to said
support member, the arrangement being such that, in use,
if the mesh covering said elongate opening in said ridge
is punctured said mesh overlying said elongate opening
can be removed and the open cell formed thereby fitted
with a plug.
The ridges and channels increase the surface area
of the screen without increasing the overall dimensions
of the screen, thus improving flow capacity.
Additionally, with the vibration, particles tend to drop
into the channels, leaving the tops of the ridges
exposed to fluids for relatively unimpeded flow through
the screen that further improves flow rates.
Furthermore, the ridges and channels tend to assist in
distributing separated particles across the screen.
Uneven distribution, due to for example rolling of the
screen from side to side when used on offshore
platforms, degrades the flow capacity of the screen.
According to another aspect of the invention there
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is provided a frame for supporting a screen, which frame
comprises a plurality of spaced-apart strips secured to
and between spaced-apart sides, characterised in that at
least one of said strips is provided with at least one
projection to be received in a corrugation in a
corrugated screen.
The present invention also provides a panel for a
screen, said panel comprising a plurality of groups of
perforations, each group comprising six generally equal
triangular apertures arranged with their apices facing a
central portion, wherein the apices of two opposing ones
of said triangular apparatus are spaced apart further
than the apices of opposed ones of the remaining
triangular apparatus.
Preferably, in the above one aspect, the bottom of
the channels are generally 'v' shaped, the bottom of at
least one of the channels is substantially flat and is
provided with at least one elongate opening which is
wholly contained within the channel, such that, in use,
the mesh is positioned to cover the elongate opening in
the channel, the mesh is capable of being punctured and
removed and the open cell formed thereby fitted with a
plug.
Desirably, the channel of the one above aspect and
the ridge include sides, at least one of which is
provided with at least one elongate opening which is
wholly contained within the side such that, in use, the
mesh is positioned to cover the elongate opening in the
side, the mesh capable of being punctured and removed
and the open cell formed thereby fitted with a plug, the
elongate opening only extends across the side or the top
of the ridge or the elongate opening only extends across
the side or the bottom of the channel.
Moreover, it is preferable the above one aspect
further comprises a second layer of mesh bonded to the
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support panel , and a third layer of mesh bonded to the
support panel.
In the one other aspect of the present invention
there is provided a screen assembly for a vibratory
separator, the screen assembly comprising a corrugated
support plate having a plurality of alternating raised
portions and lower portions, the corrugated support
plate having a plurality of spaced apart openings
therethrough, a screen frame with a first pair of spaced
apart first sides and a second pair of spaced apart
second sides, the first sides spaced apart by the second
sides and connected thereto, the frame having a
plurality of spaced apart support strips extending
beneath the corrugated support plate, each support strip
independent of and not connected to the other support
strips along its length, each support strip having two
spaced apart ends each connected to a spaced apart side
of the frame and to which the corrugated support plate
is secured, wherein each support strip has at least one
projecting portion for reception within a raised portion
of the corrugated support plate, and screening material
on the corrugated support plate.
It is desirable the plurality of spaced apart
support strips are made of a material from the group
consisting of metal, plastic, fiberglass, rubber or
cermet, the spaced-apart openings of the corrugated
support plate are triangular, the spaced-apart openings
are positioned side-by-side in an array that extends
across substantially all of the corrugated support
plate, and the array comprises rows of triangular
openings, each row including a repeating pattern of a
first, second, and third triangular opening, the first
and third triangular openings positioned with a main
base down and a vertex pointing away from the base, the
second triangular opening positioned between the first
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and third triangular openings with a primary vertex
pointing toward a line connecting the bases of the first
and third main triangular openings and positioned
between sides of the first and third triangular
openings, the second triangular opening with a primary
base disposed beyond a line between the vertices of the
first and third triangular openings that point away from
their main bases.
It is further desirable the first triangular
openings of adjacent rows are positioned with their main
bases in a side-to-side relationship, the third
triangular openings of adjacent rows are positioned with
their main bases in a side-to-side relationship, the
second triangular openings of adjacent rows are
positioned with their primary vertices pointing at each
other, the corrugated support plate has two spaced-apart
opposed sides, each of the sides having an upturned edge
to facilitate anchoring the screen assembly to the
vibratory separator, and further comprises the screening
material comprising at least one wire mesh secured on
the corrugated support plate.
Further desirable is the at least one wire mesh is
a plurality of wire meshes. It is also further
desirable the above further comprises the corrugated
support plate made of metal, and bonding material
bonding the at least one wire mesh to the corrugated
support plate.
Preferably, the bonding material is an adhesive and
adhesive envelops solid areas of the corrugated support
plate between the spaced-apart openings of the
corrugated support plate.
It is also further desirable the corrugated support
plate is made of metal and the at least one wire mesh is
bonded directly to the corrugated support plate with no
plastic grid therebetween.
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Moreover, it is preferable the adhesive is cured
and the at least one wire mesh is in tension on the
corrugated support plate due to thermal expansion
effected during curing of the adhesive, the above
further comprises a series of openings at opposed sides
of the corrugated support plate beneath the raised
portions, and a plug in each opening beneath a raised
portion, the at least one projecting portion is at least
two projecting portions, each of the at least two
projecting portions projecting into a raised portion of
the corrugated support plate, and for each raised
portion of the corrugated support plate there is a
corresponding projecting portion of each support strip.
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For a better understanding of the present invention
reference will now be made, by way of example, to the
accompanying drawings, in which:-
Figure I is an exploded end view of a screen;
Figure 2 is a plan view of the screen of Figure 1
with parts removed for clarity;
Figure 3 is a plan view of an alternative embodi-
ment of screen with parts removed for clarity;
Figure 4 is an exploded end view of the screen of
Figure 3;
Figure 5 is a perspective view of an end portion of
a screen similar to that shown in Figures 3 and 4 under-
going repair;
Figure 6 is a top plan view of a plug for repairing
the screen of Figure 5;
Figure 7 is a cross-section of a plug of Figure 6,
taken along section line 7-7;
Figure 8 is an end view of a portion of a screen
similar to that shown in Figure 5 mounted to the basket
of a shaker, showing a latching mechanism for securing
the screen to the shaker;
Figure 9 is a side view of the screen illustrated
in Figure 1;
Figures 10 and 11 are end views of screens in
accordance with the present invention;
Figure 12 is an end view of an alternative plug;
and
* * *
Fig 13a is a plan view of a frame in accordance
with the present invention for supporting a screen;
Fig. 13b shows, to an enlarged scale, a detail of
the frame shown in Fig. i3a;
Fig. 13c is an end view of the frame shown in Fig. ,
13a;
Fig. 1~ shows one alternative detail to the detail
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Wo 97rz89o6 PCT/GB97/00385
shown in Fig. 13b;
,a Fig. 15 shows another alternative detail to the
detail shown in Fig. 13b;
* * *
Fig. 16 is a plan view of a panel for a screen;
Fig. 17 is a plan view of a panel for a screen in
accordance with the present invention;
Fig. 18 is a perspective view of a screen;
Fig. 19 shows, to an enlarged scale, a detail of
the screen shown in Fig. 18;
Figs. 20 to 24 show end views of five different
embodiments of corrugated panels mounted on supports.
Referring to Figures 1 and 9, there is shown a
screen 100 which includes a first Layer 102 of wire mesh
and a second layer 104 of wire mesh. Preferably, the
first layer 102 is made from a web of bolting cloth
grads wire mesh. The second layer 104 is a backing
mesh. The first and the second layers 102, 104 are
supported on a panel 106. The panel 106 is formed to
create a plurality of ridges 108 running the length of
the screen 100, defining therebetween a plurality of
channels 110. The channels 110, which can be clearly
seen in Figure 2 (in which the first layer 102 and
second layer 104 of wire mesh have been omitted for
clarity), run the length of the screen 100 from the back
end of the screen 100 to its front end 112. Attached to
each side of the screen are hook straps 114. Each hook
strap 114 is bonded to the frame 106 and the first layer
102 and second layer 104. Steel straps 116 support the
first and second layers 102, 104.
The screen is secured to a shaker in a well. known
manner by hooking around the hook straps 114 and tight-
ening rails disposed along the edges of the basket of
a
shaker (not shown). A series of stringers below the
screen (not shown) cause the screen to bow as the rails
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pivot downwardly as they are tightened.
During operation, material containing solids to be
separated is poured onto the back of the screen. Solids
tend to collect in the channels and move towards the
front end 112 of the screen 100 when the screen is
vibrated. Fluid and particles smaller than the openings
in the finest layer of mesh flow through the mesh along
the sides of ridges 108 and the bottoms of channels 110.
Referring now to Figures 3 and 4, in an alternate
embodiment of screen 400, a first layer 402 of wire
mesh, a second layer 404 of wire mesh and a third layer
405 of wire mesh ( the layers 402, 404, 405 are shown
only in,Figure 4 exploded away from panel 302) are
bonded to panel 302.
The first and second layers (402, 404) are a bol-
ting cloth grade wire mesh. The third layer 405 is a
mill grade or market grade wire mesh supporting the
first and second layers 402, 404. The panel 302 is
formed from a sheet of metal by punching or cutting an
array of elongated, rectangular openings 304 into the
sheet of metal according to a predetermined pattern.
The openings have uniform size and shape. The sheet is
then bent with a press or rolled into a corrugated
configuration substantially as shown in Figure 4. The
corrugated configuration is comprised of alternating
series of triangular shaped ridges 306 and flat bottom
channels 308. Each triangular ridge 306 has two sub-
stantially flat side surfaces separated by a narrow peak
309.
Along each end of the panel is bonded a frame 310.
Frame 310 is contoured to fit and provide support for
the ridges 306. The screen is formed so that its side
edges run along the peak of a ridge 306. Terminating
the sides of the screen along a ridge helps to prevent
material from falling between the screen and the inside
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wall of a shaker basket (not shown) over which the
screen is placed.
Each opening 304 is located on a flat surface of
either a side of a ridge or a bottom surface of a chan-
nel. The rectangular shape of the openings allows as
much of the flat surface to be cut with openings as is
possible while leaving enough solid area to remain to
form a gr~.d or lattice-like structure that will retain
its shape and not break during normal use.
Once the panel is formed, the first layer 402, the
second layer 404 and the third layer 405 of wire mesh
are heated and then banded to the panel. The heating
expands the wire mesh. After the wire mesh a.s bonded
to
the panel, it cools and contracts, thus tensioning the
wire mesh. Tensioning helps to maintain uniformity of
the wire mesh and to keep the first 402 and second 404
layers of wire mesh together during operation, thus
giving the screen a finer cutting point. Tensioning the
wire mesh also assists in conveying particles to the end
of the screen. A slack screen will not convey particles
as well, especially when heavily loaded.
Referring now to Figure 5, a perspective view of s
portion of a screen 400 shows a layer of wire mesh 502,
which includes wire mesh webs 402, 404 and 405 (Fig. 4)
bonded to panel 302. Should a tear develop in wire mesh
layer 502, the wire mesh surrounding the tear is cut
from around the opening 304 in which the tear occurs.
A
plug 504 is then inserted into the opening in the screen
to seal the screen.
Referring now to Figures 6 and 7, plug 504 is made
of an elastic rubber or similar elastomeric material.
lts width and length are very slightly larger than one
of the openings 304. Tt has a flat top section surroun-
' - ded on all sides by a skirt-like side edge 702. The
side edge is adapted for enabling the plug to be manual-
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ly inserted into one of the openings 304 and to seal
securely against the side of the opening. The side ,
edges have an outwardly tapering bottom section 704 and
a channel 706. The tapering bottom section is suffici
ently flexible to deflect,inwardly under force of the
edges of the opening when the plug is pushed into the
opening. Deflection of the bottom of the sides pulls
inwardly a lower edge of channel 706, thereby providing
sufficient clearance to push the plug further down into
an opening 304 to the point the upper edge of the chan-
nel engages the upper edge of the opening. The width of
channel 706 is slightly larger than the thickness of the
edge of an opening 304 (which includes the thickness of
the panel and two layers of wire mesh). Therefore, the
bottom tapering section 704 springs back, locking the
plug into place and sealing it against the edges of the
opening. Support ribs 708 provide lateral strength to
the plug so that it does not deflect downward when
loading during operation, in a manner that would pull
the top edge of the channel away from the edge of the
opening and allow the load to force the plug through the
bottom of the opening.
Referring to Figure 8, the screen 400 a.s secured to
a basket of a shaker (not shown) using cam latch 804.
Cam latch 804 is secured to side wall 806 of the basket
802. A latching end of latching bar 808 extends through
an opening in the wall to engage the top of screen and
to force the screen against bracket 810. Handle 812
pivots about pin 814. U-bolt 816 is connected through
rod 818. Rod 818 extends through handle 812. The other
end of the U-bolt {not seen) is connected in a similar
fashion to ether end of the rod so that the U-bolt is
permitted to swing about rod 818 under the handle 812.
When handle 812 is pivoted upwardly, the saddle of the
U-bolt lifts up on latching bar 808, causing the latch-
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ing bar to pivot about pin 820 and press against the
screen. Pulling down on handle 812 lowers the saddle of
U-bolt 816, permitting the latching bar to pivot coun-
ter-clockwise and release the screen. To assist in
quickly replacing the screen, slot 822 allows pin 820
to
be moved back and thus allows the latching member 808
to
be pulled behind the side of the basket.
Fig. 10 shows a screen 900 lake the screen 100
(Figs. l, 2) with a similar length and width (see Fig.
2), but with a somewhat different screen shape as viewed
from the end (e.g. as in Fig. 1). The screen 900 has a
first layer of wire mesh 902 and a second layer of wire
mesh web,904 mounted on a perforate panel 926'. It is
within the scope of this invention to use only one
screening layer for any screen described herein or to
use three or more layers. A frame 906 (like the frame
of the screen 100) supports the mesh and/or screening
layers. In one aspect the layers shown for the screen
rest one on top of the other and in another aspect one
or more or all of the layers are bonded together and in
another aspect they are bonded to the frame across their
entire surfaces or only around the periphery thereof.
The frame 906 is configured and shaped to correspond to
the corrugated or undulating shape of the layers) above
it; alternatively the layers) may be made to correspond
to the shape of the frame. Ridges 908 have relatively
elongated fiat tops as compared to the apices of the
ridges of the screen 100 and flat valleys 912 of the
frame 906 are relatively short as compared to the val-
leys of the screen 100. The elongate flat tops facili-
tate the insertion of an effective plug if the ridge is
damaged. It is within the scope of this invention for
the ridges and valleys to have any desired width or
shape.
Fig. 11 shows a screen 920 like the screens 100
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(Figs. 1, 2) and 900 with a similar length and width
(see Fig. 2), but with a somewhat different screen shape
as viewed from the end. The screen 920 has a first
layer of wire mesh 922, a second layer of wire mesh web
924 and a third layer of mesh or screening 928. A panel
926 (like the panel of the screen 900) supports the mesh
and/or screening layers. In one aspect the layers shown
for the screen rest one on top of the other and in
another aspect one or more or all of the layers are
bonded together and in another aspect they are bonded to
the frame across their entire surfaces or only around
the periphery thereof. The screens 900 and 920 may be
used with or without straps (e.g. as the straps 114 and
116, Fig. 9). Individual cells of the screens 900 and
920 may be shaped as the individual cells of the screens
of Figs. 2 and 3 or they may be any desired shape,
including but not limited to, oval, square, trapezoidal,
or triangular (acute, obtuse, isosceles, congruent).
The cells of the screens 900 and 920 are repairable as
are cells of the previously-described screens.
Fig. 12 shows a plug 950 for plugging off a cell of
a screen according to the present invention. The plug
950 has a body member 952 and ears 956 which project
from legs 954 depending on the body member 952. The
plug 950 is made from a resilient material so the legs
954 are bendable to permit the ears 956 to enter a call
to be repaired and then expand outwardly so the ears
catch and hold on an edge of the cell.
It is within the scope of this invention to have a
plug held in a cell by friction fit, any "snap fit"
structure, welding or adhesive. Accordingly, a plug may
be any desired shape to fit in and mate with the shape
of a cell. The plug may be solid or it may be solid with
openings, holes or perforations therethrough. In one
aspect in which a cell is not initially behind a torn
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screen area a cell or cells is placed at the torn cone
area on one side of the screen and a plug is inserted
into the cell from the other side of the screen to
repair a torn area.
* *
Fig. 13a shows a screen frame 500 according to the
present invention with a plurality of spaced-apart
strips 502 (made of any suitable metal or metal-like
material) secured to and between spaced-apart sides 504.
Each end 506 of each strip 502 is received and held in a
recess 524 in a side 504. The recess 524 corresponds in
shape to the shape of the end 506 and a shoulder 526 of
each strip 502 abuts a side 504. The end 506 may be
inserted into the recess 524 from the side (to the left
in Fig. 13b) or from above or below. The top and bottom
strips 502 (as viewed in Fig. 13a) each has two humps or
ridges 553 {see Fig. 13c) which are located, sized, and
configured to be received in corresponding corrugations
of a corrugated plate and/or corrugated screen assembly.
It is within the scope of this invention for each strip
to have one, two, or a plurality of multiple humps or
ridges. In one aspect there is one hump or ridge for
each corrugation of a superimposed plate and/or screen
assembly.
Fig. 14 shows a strip interlocking structure which
includes a bulb 505 at each end of a strip 503 (disposed
in a frame as are the strips 502). The bulb 505 is in a
recess 525 in a side 501 (like the sides 504). The bulb
505 is lifted out from the recess 525 for removal or
inserted into it from below or above for installation.
Fig. 15 shows a strip interlocking structure which
includes a tongue 509 at each end of a strip 508 (dis-
posed in a frame as are the strips 502). The tongue 509
is in a recess 530 in a side 507 (like the sides 504).
The tongue 509 is lifted out from the recess 530 for
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removal or inserted into it from below or above for
installation. An enlarged end 531 resides removably in
a recess 532 and prevents the strip 508 from
inadvertently moving out from the recess 530 to the side
(to the left in Fig. 15).
Fig. 16 shows a pattern of triangular openings in a
perforated panel 510 (made of metal or metal-like
material). The openings 511 are positioned side-by-side
in an array that extends across substantially all of a
panel. The panel may be corrugated or flat or a
combination thereof with alternating flat and corrugated
portions.
Fig. 17 shows the pattern of the triangular
openings for the perforated plate 512. It will be noted
that openings 514 and 515 are spaced apart from each
other slightly more than the middle openings of the
plate 510 producing, in certain embodiments, stronger
central portions 550. The panel may be corrugated or
flat or a combination thereof with alternating flat and
corrugated portions.
In the pattern of openings as in Fig. 17, the
pattern is shifted slightly as compared to that of the
plate 510 to optimize use of a screening surface. For
example, a screen using the pattern in Fig. 16 and a web
width (distance between two adjacent openings) of 3.17mm
(0.125"), has a border on each edge. By shifting the
triangle openings to the pattern of Fig. 17, a web width
of 3.17mm (0.125") may be maintained while decreasing
the border. This allows more openings in the screen of
Fig . 17 as compared to that of Fig . 16 , thus increasing
surface area and improving appearance.
In the pattern of Fig. 16, the openings are
arranged in rows with bases and peaks alternating. The
peak of one opening is level with the base of the next.
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In the pattern of Fig. 17 the openings 5i3 are moved
claser together and the peaks of the openings 513 are
not level with the base of the opening 514 or 51,5.
Figs. 18 and 19 show a screen 530 with a corruga
ted support panel 540 (preferably made of metal) having
a plurality of triangular openings 538 (not shown in
Fig. 18; see Fig. 19 ) thereacross the surface of and
therethrough; optional upturned edges 534 and 537 for
anchoring the screen 530 to a vibratory shaker; wire
mesh or meshes 539 secured to the panel 540; and plugs
535 at both ends to plug ridge openings 532 at each end
of the corrugations of the plate 540. The plate 540
rests on~.and is secured to a strip or strips 551 (alter-
nately a frame of multiple strips crass-crossing the
plate 540 or a series all in the same direction, or a
perforated glate may be used). In one aspect the
strips) 551 are omitted. The strips 551 may be made of
any suitable material, including, but not limited to,
metal, plastic, fiberglass, rubber, or cermet.
A screen according to the present invention may be
made without a plastic grid located between a lower
panel and screens) or meshes) above the plastic grid.
when screening material is bonded to a corrugated per-
forated panel (e. g. as in Fig. 19), thermal expansion
guts the screening material in tension. Such a result
is not produced when a plastic grid process is used. A
metal corrugated perforated panel withstands tension
induced thereon by screening material applied and/or
bonded thereto. In one aspect the panel is first covered
with adhesive (e. g. powdered epoxy) then the meshes)
and/or screens) are placed on the panel. Upon curing of
the epoxy, adhesive 541 covers or envelops part of the
mesh/scresn at the solid areas of the panel.
Figs. 20-24 present a variety of configurations for
corrugated perforated panels according to the present
CA 02240693 1998-06-15
WO 97128906 PCT/GB97/00385
- 16 -
invention and/or for strips according to the present
invention.
Fig. 20 shows a corrugated panel A on a support
strip B having optional
mounting hooks C.
Fig . 21 shows a corrugated panel D on a support
strip E. Optionally, mounting hooks may be used with
such an assembly.
Fig. 22 shows a support strip F. A corrugated
perforated panel may have such a configuration and
mounting hooks may be used with the strips or with the
plate.
Fig. 23 shows a support strip G. A corrugated per-
forated panel may have such a configuration and mounting
hooks may be used with the strips or with the plate.
Fig . 24 shows a corrugated panel H on a support
strip I having optiona l mounting hooks J.
Any mesh, meshes, screen, screens, screening mater-
ial ( s ) or any combination
thereof or any such
as de-
scribed herein may be used with any of the items shown
in Figs. 13-24.
3D
