ECRAN AJOURE

SCREEN

Abrégé anglais

Abstract

In a screen consisting of a supporting frame (1) which
is covered with apertured (6) screen elements (2) of
resilient material, said screen elements (2) are well
supported and particularly easy to replace without
intervention, e.g. by way of welding, as they have
longitudinal guide grooves (7) which have a profile
serving to be snapped on to the upper layer (3) of the
supporting frame (1) and such a depth that the lower
layer (4) of the supporting frame (1) engages the
underside of the screen elements (2). In a preferred
embodiment the wires or bars in the lower layer (4) of
the supporting frame are disposed so as to be out of
alignment with the apertures (6) of the screen elements
so that also the wires in this layer are protected
against wear.

Revendications

Claims:
1. A screen consisting of a supporting frame on whose
upper side rectangular, mutually adjoining, apertured
screen elements of resilient material are detachably
attached, characterized in that the supporting frame
consists of an upper and a lower layer of substantially
rectilinear, mutually parallel metal bars, the bars in the
upper layer being disposed transversely to the bars in the
lower layer and joined with the bars of said layer in the
intersections, each screen element having at its underside
at least two longitudinal guide grooves located outside
the areas of the apertures, said guide grooves having a
profile permitting said grooves to be snapped on to the
upper layer of bars of the supporting frame, said guide
grooves having such a depth that the lower layer of bars
of the supporting frame can engage the underside of the
screen elements.


2. A screen according to claim 1, characterized in that
the bars in the lower layer of the supporting frame are
disposed so as to he out of alignment with the apertures
of the screen elements.



3. A screen which comprises a supporting frame on whose
upper side mutually adjoining, apertured screen elements
of resilient material with substantially rectangular
borders are detachably supported, said supporting frame
comprising an upper and a lower layer of substantially
rectilinear, mutually parallel metal bars, the bars of
the respective layers lying essentially in only their
own layer, the bars in the upper layer being disposed
transversely to the bars in the lower layer and joined
with the bars of said lower layer at intersections of
said bars of said respective layers, each screen element
having at its underside at least two longitudinal guide
grooves located at borders outside the areas of the






apertures, said guide grooves being constructed and
arranged to be snapped onto the upper layer of bars, said
guide grooves having sufficient depth that the lower layer
of the bars of the supporting frame can engage the under-
side of the screen elements when the screen elements are
supported by the upper layer.


4. A screen according to claim 3, in which opposing sides
of the guide grooves are provided with recesses for accomo-
dating the passage of the transversely extending bars of
the lower layer.


5. A screen according to claim 4, in which the bars in
the lower layer of the supporting frame are disposed so as
to be out of alignment with the apertures of the screen
elements.


6. A screen according to claim 3, in which a plurality of
apertures in the screen element lie within the rectangular
borders of said screen element.


7. A screen according to claim 3, in which the bars of
both layers are substantially round.


8. A screen according to claim 3, in which the bars of
both layers are substantially uniform in shape.

Description

A screen

The invention relates to a screen consisting of a
supporting frame on whose upper side mutually adjoining,
apertured .screen elements of resilient material with sub-
stantially rectangular borders are detachably attached,

The apertured screen elements of resilient material are
primarily to serve as wear-resistant screen means proper,
but also have the task of protecting the supporting frame
a~ainst the wear caused by the material treated by the
screen.

llowevcr, the screen elements are nevertheless worn or
otherwise damaged over an ex~ended period o~ time, e.g. by
~alling screen material, and must therefore be replaceable.

Norwegian Published Application 142 943 ~published on
November 21, 1977, inventor: Kur~ ~olff~ discloses a
lS screen of the type mentioned above, in which the replace
able screen elements are attached to the supporting frame
by means of stud-shaped fasteners. Th s technique is
vitiated by the drawback that it requires the use of a
very large number of fasteners, which can easily be lost
and which can spring up when the frame is deflected~
Moreover, the fasteners are damaged more or less when
the screen elements are replaced.


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Screens have been developed in which the fasteners are
integral parts of the screen elements~ However, this
involves a very complicated manufacturing process which
adds to the manufacturing costs of ~he screen elements.
The integral fasteners moreover break when the indLvidual
screen elements are replaced. ~he resulting bottom frame
becomes heavy, which reduces the vibra~ion capacity of the
machine ~

West German Gebrauchsmus~er No. 7 838 335 applied for by
Gummi-Kuper GmbH & Co, Kg. and published on April 5, 1979,
discloses a further development of a screen where the
screen elements are attached by means of fasteners, which
are firmly conrlected to a supporting structure~ These
fasteners are rectilinear, specially made metal prQfiles
l.S with an upwardly open U-shaped cross-section, whose
~ree forks are extended at th~ top and lockingly engage
longitudianl notches in the edges of their respective
one of two adjoining screen elements. Thus, the screen
elements are only supported at their longitudinal edges
2~ as there i5 nc supporting frame, and the load capacity
o~ the screerl i5 therefore not fully satisfactory.

Another known screen comprises a supporting frame of
woven, speciall~ made profile wires which are disposed
perpendicularly to one another and to which rubber screen
elements are attached, the screen elements being provided
along all their edges with downwardly open grooves which
can be clamped onto the wire netO The wire net cannot
carry large loads without being deflected~ and this con-
struction is therefore not capable of supporting the
screen elements to a satisfactory degree either. The
rubber in the screen elements must moreover be so thin
that it can easily be replaced, but this signi~icantly
reduces the wear resistance.



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The object of the invention is to form the screen elements
so that, without the use of loose fas~enersl they can be
attached directly to and be firmly supported by a very
rigid and pressure resistant supporting frame, which is
quite conventionally attached without any intervention in
the machine by way of welding, and from which the screen
elements are easy to remove or mount in case of replace-
ment. It is a further objec~ that the screen is easy
to adapt to various mesh sizes by replacing the screen
elements by others which have different aperture sizes,
but fit on the same supporting rame, which ~an he con
ventionally replaced easily and rapidly by a supporting
frame of a differen~ module

These objects are achieved according to the invention by
constructing the screen defined in the foregoing so that
the supporting frame consists of an upper and a lower
layer of substantially rectilinear r mutually parallel
metal bars, the bars in the upper layer being disposed
transversely to the bars in the lower layer and joined
~o wlth the bars of said layer in the intersections, each
screen element haviny at its underside at least two
longitudinal guide grooves located outside the area of the
apertures~.said guide grooves having a profile permitting
said grooves to be snapped on to the upper layer of bars
of the supporting frame, said guide grooves having such a
depth that the lower layer of bars of the supporting frame
can engage the underside of the screen elements. When the
individual screen elements are to be replaced, they are
just pulled upwards with a certain force in a direction
perpendicular to the plane of the supporting frame so as
to remove the clamping effect of a snap fastener nature
between the guide grooves and the upper layer of metal
bars in the supporting frame~ The new screen elements are
then brought into place with the guide grooves just above
the upper layer of metal bars and are snapped on by being


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pressed downwards. The overall screen or mesh area can be
increased by 20 to 30~ over the previous know~ construc~
tions owing to the effective support provided by the frame.

The supporting frame may be a standard screen of the type
which was previously used for screening purposes and which
can be mounted on all known screening machines without
changing the frame of the machine or its set-up.

The screen elements themselves may have a mesh opening
from 1 mm and up to 100-120 mm without any change of the
supporting frame. The supporting frame for such a screen
may easily be produced even under the simplest manufac~
turing conditions merely by inverting the screen elements
alld then placing round bars in the guide grooves, where
they may then be attached to form a net, which in turn is
welded correctly to~ether when the round bars have been
removed from the screen elements.

The m~nu~actured screen elemen~s are also advantageous in
term~ o~ casting~ They can be made of plastics or rubber
or another resilient material, which may optionally be
reln~orcedO

When the wires or bars in the lower layer of the support~
ing frame are disposed so as to be out of alignment with
the apertures of the screen elements, provision is made
for support to the full extent of the bars in the lo~er
layer of the supporting frame, and these bars are covered
at the same time and thus protected in their full extent
by the screen elements.

The invention will be described more fully below with
reference to ~he drawing, which shows a perspective view
of an embodiment of a screen according to the invention,
seen obliquely from below.


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The drawing shows a supporting frame l and two identical
screen elements 2, one of which is shown attached to the
supporting frame 1, and other is shown in a position
vertically above the supporting frame l.

The supporting frame 1 consists of a plurality of recti-
linear, mutually parallel metal bars 3, which are disposed
in an upper layer, and a plurality of likewise rectilinear~
paralLel metal bars 4, which are disposed perpendicularly
to the bars 3 of the upper layer and are a~tached to the
underside of the upper metal bars 3, e.g. by welding, in
the intersections S of the wires 3,4. It will be noted
that the bars 3 of the upper layer and the bars 4 of the
lower layer lie in only their own layer. Bars 3 and 4
are generally uniform in shape.

The screen elements 2, which have rectangular borders are
provided with aper~ures 6 through which the material to
b~ treated i5 passed. The screen elements have on their
unclerside three guide grooves 7, which are not aligned
with the areas o~ the apertures 6 and have such a profile
that they can be snapped on to the upper layer of metal
wires 3 in the supportin~ ~rame.

The guide grooves 7 have such a depth that the lower layer
of bars 4 of the supporting frame engages the underside of
the screen elements 2 when the screen elements are attached
to the supporting frame l. Moreover, the metal bars 4 in
the lower layer of the supportiny frame l are disp~sed so
that they are out of alignment with the apertures 6 of the
screen elements 2.

In the shown embodiment the sides 8 and 9 of the guide
grooves 7 extend downwardly past the lowest layer of metal
bars 4 and are therefore provided with recesses lO at each
intersection for the passage of the metal bars 4 .


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