FIELD OF THE INVENTION
The present invention relates to mechanical separators and screening
machines, and more particularly relates apparatus and method for
flexible sieve mat screening using a flip-flow type mat screening
apparatus. In an example configuration, a flip-flow type flexible mat
screening apparatus is provided with optimized relative elevation
positions for adjacent pairs of first and second mat supports. In one
configuration, a portion of the first mat support is arranged at a lowered
or offset position relative to adjacent second mat support (not shown in
the figure).
BACKGROUND OF THE INVENTION
Conventionally, various designs have been proposed for sieve mat
screening machines and one of the basic designs known in the art is a
sieve mat screening machine with fixed screen decks. In an attempt to
overcome the blinding problems associated with the rigid panels, It is
known to use screening apparatus which makes use of elastically
deformable screening panels formed of an elastomeric material. These
panels are attached to a so-called floating frame which shakes the panels
at a high frequency, thereby reducing the blinding effect associated with
rigid panels. This type of screening apparatus is sometimes referred to as
a "flip-flow" screen.
A problem associated with the "Flip-flow" technology is that it is relatively
expensive. In addition, in screening installations, e.g. in an ore treatment
plant, use is often made of several machines located one next to the
other. As a consequence replacing a conventional rigid screening unit
with a "flip-flow" type screening unit is both difficult and expensive.

Furthermore the down time required to replace an installed screening
machine with another technology like a flip-flow screen is substantial
and it is well understood that any interruption in the operation of a
mining or bulk material producing plant will have an adverse impact on
profitability. Besides, the decision to replace an existing screening
machine with a flip-flow screen is not guaranteed to solve the blinding or
screening efficiency problem. This results in a reticence to pay for a new
technology and interrupting plant production which has an adverse
impact on productivity where no or only a minor benefit may be
obtained.
Further, WO2016016322A1 tries to solve some of the aforesaid problems
by disclosing a screening apparatus, particularly for mining or bulk
material production plant, which comprises: at least one screen deck
having a support structure; a plurality of spaced apart clamp bars,
attached to the support structure, said clamp bars being formed, at least
in part, of a resiliently deformable elastomeric material; and a plurality of
resiliently deformable screening panels secured to said clamp bars.
However, the solutions provided by WO2016016322A1 through specific
arrangement of the various mat screening apparatus is not complete. For
example, in said prior art the arrangement of the components do not
cause the much needed acceleration. Further, the placement of the
floating frame is desired to such so that the flip-flow motion is optimum
to sieve the particles of sizes as low as possible. Furthermore, said prior
art implements additional hanging/supporting arrangement for placing
the floating frame. Additionally, the load bearing capacity of the
apparatus disclosed in the prior art is much lesser since the overall
structure disclosed is not configured in the manner to withstand more
acceleration.

Furthermore, US20050274653A1 a screening machine having an
elongated support frame with a mobile, deformable sieve mat, typically
comprised of a plurality of sieve mat sections and a series of alternating
first and second sieve mat supports mounted on the support frame and
extending transversely along the length, the sieve mat sections being
affixed to a pair of the first and second mat supports with the mat
supports being movable with respect to each other in the direction of the
length of the support frame. During cycling of the screening machine, the
individual screen mat sections are alternately tensioned and relaxed
creating a high-acceleration trampoline effect (“flip-flow” method).
However, in said patent application the components being used to
prepare the apparatus is made out of plastic and flexile non-metallic
fabrics where the ideally for best performance the material making up
the apparatus preferably needs to be metallic and welded profile.
Furthermore, the profile disclosed by said patent application is curved
which has its disadvantages again. Furthermore, the floating channel
mounting style as taught certainly needs improvement. Lastly, the
mechanism for fixing the screen deck in said patent application also has
a scope of great deal of improvement.
The present application has recognized certain problems and limitations
inherent in the prior sieve mat screening machines as also elucidated
above.
OBJECTS OF THE INVENTION
An object of the invention is to overcome the aforementioned and other
drawbacks existing in prior art systems and methods.

Another object of the invention is to develop a flip-flow type mat
screening apparatus and method for fine sieving of articles.
Yet another object of the invention is to prepare the screen deck of the
flip-flow type mat screening apparatus in a manner as to ensure
homogeneous distribution of materials across the screen deck.
Still another object of the invention is to mount the floating frame such
that (responsible for causing flip-flow motion) the damping ratio is.
higher.
Another object of the present invention is to ensure that the flip-flow type
mat screening has relatively higher strength than such apparatuses
existing in the prior arts.
SUMMARY OF THE INVENTION:
The present application discloses a flip-flow type mat screening
apparatus for fine sieving of articles as described in Fig.1 vividly. In one
aspect, the apparatus includes a support frame mounted on a base. The
apparatus further includes, a screen deck having plurality of mat
sections spaced transversely across the length of the support frame
where plurality of mat sections are secured to plurality of lifting lugs
.Further, the apparatus includes, a side plate mounting a plurality of
cross members, a vibration assembly, a feed box, a discharge lip, the
plurality of lifting lugs and a plurality of back plates where the vibration
assembly is configured to vibrate the screen deck and providing desired
torque thereof. Furthermore, the apparatus includes a spring assembly

pivotally connected to the side plate via a spring pad where the assembly
comprising a plurality of supporting springs and a spring pivot. Further,
in an aspect, the spring pivot is configured to apply material load fed on
the screen deck via a feed box to the plurality of supporting springs,
thereby changing slope of the screen deck. Furthermore, the apparatus
includes a floating frame having side angles, rubber blocks and side
channels configured to generate flip-flow motion in the screen deck
disposed in the support frame. The apparatus further includes a motor
assembly mounted relative to the side plate configured to operate the
aforesaid apparatus.
In another aspect, the present application disclosing a flip-flow type mat
screening method for fine sieving of articles includes fixing a screen deck
on a support frame. The method further includes, vibrating the screen
deck and feeding matter to be screened onto the screen deck towards a
feed end thereof. Furthermore, in an aspect, the method includes moving
the matter to be screened from the feed end to chute, wherein chute is a
discharge end.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The drawings refer to embodiments of the invention in which:
Fig. 1 illustrates a live frame assembly of Flip-Flow Screen.
Fig. 2 illustrates a 3D view of the flip-flow type mat screening apparatus
for fine sieving of articles.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
Although the disclosure hereof is detailed and exact to enable those
skilled in the art to practice the invention, the physical embodiments
herein disclosed merely exemplify the invention which may be embodied
in other specific structure. While the preferred embodiment has been
described, the details may be changed without departing from the
invention, which is defined by the claims.
It will be apparent, however, to one of ordinary skill in the art that the
present invention may be practiced without specific details of the well
known components and techniques. In other instances, well known
components or methods have not been described in detail in order to
avoid unnecessarily obscuring the present invention. Further specific
numeric references should not be interpreted as a literal sequential
order. Thus, the specific details set forth are merely exemplary. The
specific details may be varied from and still be contemplated to be within
the spirit and scope of the present invention. The features discussed in
an embodiment may be implemented in another embodiment.
For the purposes of this description, this machine is referred to as a “flip-
flow” type screening machine. Additionally, in certain embodiments, the
present invention builds upon the disclosures of WO2016016322A1 and
US20050274653A1 which are all hereby incorporated by reference in
their entirety.

Further, it may be noted that the terms Screen/PU deck/ Screen deck/
are used interchangeably throughout the specification and hence should
not be considered to be a source of confusion for a person skilled in the
art for the purpose of enabling the disclosed invention.
Improving upon the conventional apparatuses and methods discussed at
length above, the present disclosure in Fig.1 shows a live frame assembly
of Flip-Flow Screen. The brief description of the important components
of the flip-flow type mat screening apparatus as shown in Fig. 2 is
explained below:
1) SCREEN/PU DECK (1) – In this screen we are using only PU deck
to proper the screen. Other media is not applicable for this application.
Thickness of the panel is approx 3 to 6 mm as per requirement.
2) LIFTING LUG (2) – It is a safety feature of the screen. This is
helpful for easy & safe handling of screen.
3) FEED BOX (3) – It takes the impact load of the feeding material of
the screen. It also helps to split the material.
4) BACK PLATE (4) – It restricts the spillage of the material from back
sides. It also helps to guide the material to undersize chute (not shown in
the figure).
5) SIDE PLATE (5) - It’s a most important part of the screen. All cross
members, Bucker-up frame, Vibrator Assy., Feed box, Discharge lip,

Lifting lug and back plates are bolted in same plate. It also helps to guide
and restrict the spillage of the material.
6) SPRING PIVOT (6) – It is used to apply the screen load to
supporting springs. It also helps to change the slope of the screen.
7) SPRING PAD (7) – It is used to guide the supporting spring.
8) VIBRATOR ASSY. (8) – It is the main sub-assembly of the screen. It
creates vibration in the screen and provides a desire torque.
9) DRIVE PULLEY (9) – Its use is to drive the machine through V-belt.
10) MOTOR (10) – It is used to generate the power to run the screen.
Generally this type of motor starting torque is 200 %.
11) MOTOR BASE (11) – It’s a pivoted type base. Screen motor sits on
this base. This base is able to take the shock load for smooth running.
12) SUPPORTING SPRING (12) – It takes the screen weights. Its main
function is restricting the vibration to transfer in structure. Its material
is spring steel or Rubber spring.
13) BUCKER UP FRAME/ BU-FRAME (13) – It’s mainly used for fixing
the PU Panel & takes the material load of feeding material.
14) FLOTING FRAME (14) – It consists of Side angles, rubber blocks &
Side channels. It helps to create the flip flow motion in screen.

15) DISCHARGE LIP (15) – It helps to guide the material form screen to
discharge chute is a controlled way.
16) V-BELT (16) – It helps to transfer the torque from motor to screen.
17) COUNTER WT. GUARD (17) – It’s a safety part of the screen. It
covers the rotating parts like counter weights.
18) DRIVEN PULLEY (9) – It helps to transfer the torque to screen.
Further, in an aspect, the sieve mat may be formed of any suitable
material which has the desirable properties of flexibility and strength in
addition to abrasion, rust and corrosion resistance depending upon the
particular application. For example, the material used for the sieve mats
is mechanically strong, such as a resilient elastomer with a balanced
range of properties which is able to withstand deformation without loss
of elasticity or dimensional accuracy. One such material is a resilient
flexible polymer, for example, such as polyurethane. In various
embodiments, the sieve mats may be of any suitable construction, such
as: single homogenous material construction; a multiple material
construction such as one with reinforcements such as internal cables or
bars; or multiple layer construction such as one with a suitable screen
backing or other layers.
In another configuration, the motion of the sieve mat sections (19) is
such that in the un-flexed condition (with adjacent carrier supports in
the nearer position to each other), a sag or drape will be formed. Then
moving to the flexed condition (with adjacent carrier supports moved to
the more distant position to each other), the mat section will be snapped

toward a flatter/straighter form. This motion is akin to holding a piece of
paper, forming a drape, and then in a quick motion pulling taught.
Referred to as a flip-flow method, during the cycling of the screening
machine, the flexible mat sections are individually tensioned and relaxed
which breaks or loosens the adhesive bond between materials and
between the material and the sieve mats. In the upstroke, material is
impelled upwardly functioning much like a trampoline and air is drawn
into and through the material. The motion is such that in an example
screening machine, the acceleration on the support frame (20) is about 3
g's, but the material on the sieve mat may experience up to about 50 g's.
Sieve mat flexing may also stretch or bend the mat perforations helping
to release particles that might become lodged in the perforations, a
process called “breathing.” The flip-flow method is useful for screening a
wide variety of materials, such as recycling (auto shredder residue,
crushed glass, food scraps, compost, etc.); sorting wood products (wood
chips, sawdust, wood pulp); removing abrasive fines from boiler fuel;
mineral processing and quarrying applications (sand, ore, excavated
soils, etc.); and other applications. The flip-flow machine may be
particularly useful for the more difficult applications such as:
o screening of moist, sticky, wet and fibrous materials;
o screening of small particles (separation up to (-3) mm);
o screening of materials with a high percentage of fines;
o Screening of near size particles with efficiency as above as 95%.
In another embodiment, the floating frame (14) may be mounted in a
sandwich format for attaining higher damping ratio. In another preferred
embodiment, the screen deck (1) is fixed across the support frame using
wedge-fixing i.e. the mat sections (19) are connected via fastening wedges
or suitable. Further, in another aspect end points of the screen deck (1)

is straight i.e. the profile is straight. Further, in another aspect, the
profiles are manufactured using metallic and welded profile for lending
higher strength to the apparatus.
The foregoing is considered as illustrative only of the principles of the
invention. Furthermore, since numerous modifications and changes will
readily occur to those skilled in the art, it is not desired to limit the
invention to the exact construction and operation shown and described.
While the preferred embodiment has been described, the details may be
changed without departing from the invention, which is defined by the
claims.

WE CLAIM :
1. A flip-flow type sieve mat screening apparatus particularly for fine
sieving of particles, said apparatus comprising:
a support frame(20) mounted on a base;
a screen deck (1) having plurality of mat sections (19) spaced
transversely across the length of the support frame (20), said
plurality of mat sections (19) secured to plurality of lifting lugs (2);
a side plate (5) mounting a plurality of cross members, a vibration
assembly (8), a feed box (3), a discharge lip (15), the plurality of
lifting lugs (2) and a plurality of back plates (4), said vibration
assembly (8) configured to vibrate the screen deck (1) and
providing desired torque thereof;
a spring assembly pivotally connected to the side plate (5) via a
spring pad (7) said assembly comprising a plurality of supporting
springs (12) and a spring pivot (6), said spring pivot (6) configured
to apply material load fed on the screen deck (1) via a feed box (3)
to the plurality of supporting springs (12), thereby changing slope
of the screen deck (1);
a floating frame (14) having side angles, rubber blocks and side
channels configured to generate flip-flow motion in the screen
deck (1) disposed in the support frame (20);
a motor assembly mounted relative to the side plate (5) configured
to operate said apparatus;

2. The apparatus as claimed in 1, wherein the screen deck (1) is
prepared from polyurethane plastic material.
3. The apparatus as claimed in 1, wherein the fine sieving of particles
comprises screening fine particles equal to or below 3 mm.
4. The apparatus as claimed in 1 or 3, wherein the fine sieving of
particles comprises screening efficiency of about and over 95 %.
5. The apparatus as claimed in 1, wherein the motor assembly
pivotally connected to a motor base (11) comprises a driver pulley
(9) configured to drive the vibrator assembly (8) through a V-belt
(16), a motor (10) configured to power operation of the screen deck
(1), a driven pulley (18) to transfer the torque to the screen deck (1)
via the vibrator assembly (8), a counter wt. guard (17) configured
to provide counter weights to rotating vibrator assembly (8).
6. The apparatus as claimed in 1 and 2, wherein a bucker up frame
(13) is configured to fix the screen deck (1) made of polyurethane
plastic material.

7. A flip-flow type sieve mat screening method particularly for fine
sieving of particles, said method comprising:fixing a screen deck (1)
on a support frame (20);
vibrating the screen deck (1) and feeding matter to be screened
onto the screen deck (1) towards a feed end thereof;
moving the matter to be screened from the feed end to chute,
wherein chute is a discharge end;