Note: Descriptions are shown in the official language in which they were submitted.
27026-3 8
CA 02170150 2000-11-09
Dry Sorter for Very Fine Coal
The invention relates to an installation for separating forest granular
materials, in
particular finest coal, with an angled belt path supported in a support frame,
whose conveyor
belt cover is equipped with longitudinal grooves extending in the longitudinal
direction of the
belt conveyor, with a feed which feeds at the feed-side deflection roller from
the elevated
longitudinal side, a coal discharge provided at the front of the discharge-
side deflection
roller, and a rough material discharge provided at the lower longitudinal side
of the conveyor
belt cover. The invention also relates to a process for drying and classifying
finest material,
in particular finest coal, in which the finest coal is fed from the top edge
onto the endless
and angled conveyor belt cover of a belt conveyor, whereby the finest coal
granules are
retained in the grooves of the conveyor belt cover and are discharged at the
top of the belt
conveyor, while the rough coal granules run off via the angled conveyor belt
cover and are
removed via the lower longitudinal side of the conveyor belt cover.
In the classic method of classifying materials with different granule sizes,
the mixture
is passed over a screen provided with a suitable perforation and is then
separated into
overflow granules and pass-through granules. It is also a known practice to
vibrate the
screening surface in order to accelerate the separation of the granule classes
in this manner.
Such a screening classification is so far possible up to a granule size of 10
mm and below,
but becomes more difficult and less accurate the higher the finest granule
content is. In
particular in the case of roller cutting machines and continuous miners, the
finest granule
content is very high, whereas the rubbish content in this finest granule
content is very low.
Since the processing costs for finest coal are very high and the finest coal,
which is then
moist, must then also be dried, attempts have been made to classify this
finest coal by dry
method. GB-PS 7 225 from 1914 describes an installation for classifying finest
granule
materials - in particular, coal - in which a belt conveyor is equipped with a
groove profile
conveyor belt. Due to the angled belt conveyor, the fed fine materials remain
stuck in the
grooves and are separated from the rough material which falls off the sides of
the conveyor
across the grooves. When viewed over the length of the belt conveyor, support
rollers are
arranged transversely to the running direction, which, due to their mufti-
edged construction,
generate a vibration effect in order to compensate for the disadvantage caused
by the
relatively low incline of the conveyor. This results in an inaccurate rough
particulate
containing a relatively high finest granule content. If the belt conveyor were
to be placed at
a greater angle, the belt would slip even with a relatively high preload,
whereby this effect
would even be magnified by the vibration rollers. This would result in the
frequent standstill
and readjustment of the classifier.
The invention is therefore based on the objective of creating an installation
and a
process ensuring a frictionless and efficient continuous operation of a dry
classifier.
CA 02170150 2000-11-09
27026-38
According to the invention, there is provided an apparatus for separating fine-
grained
substances, particularly fine coal, comprising an endless conveyor belt having
a topside and
an underside, a support structure for holding the conveyor belt in an angled
position, a cover
layer on the topside of the conveyor belt, longitudinal grooves extending
lengthwise along the
conveyor belt, a feed side drivable deflection roller and a discharge side
drivable deflection
roller for moving the belt, supporting rollers at spaced intervals, at least
one supporting strip
on the underside of the conveyor belt for running on the supporting rollers,
pressure rollers
positioned above the supporting strip for maintaining a position of the
conveyor belt, a feed
for feeding substances onto the conveyor belt at the topside, a fine particle
discharger
adjacent the discharge side drivable deflection roller, and a coarse material
discharger
adjacent the conveyor belt.
Such an installation advantageously makes it possible to provide different
angles for
the belt conveyor, whereby in each case, independent from the selected angle,
the conveyor
belt cover is set by the supporting strip and the associated supporting
rollers and pressure
rollers in such a way that the respective desired separation effect is safely
attained. The
separation effect is also attained in particular due to the fact that because
of the selected and
adjustable angle, preferably 35°, no vibration rollers or similar
devices are needed. The
supporting strips are hereby arranged on the underside of the conveyor belt
cover, so that they
do not adversely affect the classification result, whereby it is also
advantageous that the
supporting rollers are also positioned between the carrying run and the
returning run, so that
they, as such, do not cause any adverse effect, but also cannot be affected
adversely by the
charged material. Only the pressure rollers, which ensure an even support
through the
supporting rollers, are provided on the top side in relation to the carrying
run, whereby they
can be secured by means of appropriate protection devices. In addition, only a
few of these
pressure rollers are required over the length of the belt, so that they, as
such, also do not
represent a hindrance to the operation of the belt conveyor. The advantage is
that such an
installation creates a dry classifier which is optimally suited for continuous
operation and
which enables constant, dry classification, so that the finest material can
already be separated
prior to feeding the fine coal to the jigging machine. The expensive drying
required in the
past is not longer necessary.
A useful embodiment of the invention provides that the conveyor belt cover is
equipped on both sides with a supporting strip which is associated at a
distance also with
supporting rollers positioned at the lower longitudinal side. This supports
the conveyor belt
cover on both sides, whereby the lower supporting rollers ensure that the
conveyor belt cover
or the conveyor belt run does not move upwards. Rather, it is precisely set by
the bilateral
arrangement of the supporting strip and the supporting rollers. However, in
the case of the
supporting rollers associated with the lower longitudinal side, the pressure
rollers are no
longer necessary, since here a folding-up or creeping-up from the area of the
supporting
rollers need no longer be feared.
Another useful embodiment provides that the returning run of the belt conveyor
is
associated at a distance with supporting rollers and pressure rollers, so that
even the carrying
run is held precisely, thus safely preventing slipping on the one hand, and
also a moving-up
of the belt in the angled position.
2
27026-38 ca o2moiso Zooo-ii-09
A useful embodiment concerning the supporting strip provides that the
underside of
the conveyor belt cover is glued to the supporting strip which is constructed
as a rectangular
rubber or plastic profile. This construction has the advantage that profiles
which correspond
to the respective application, i.e., to the necessary respective length of the
belt conveyor, can
be inserted. In the case of a correspondingly wide profile, the necessary
pressure can also be
easily absorbed by the supporting strip, thus ensuring the necessary securing
of the conveyor
belt cover.
In order to ensure that the conveyor belt cover is also set and supported
correctly via
the supporting rollers, the invention provides that the plastic profile has a
width
corresponding to the width of the supporting rollers, whereby, as a rule, the
supporting
rollers are somewhat wider than the supporting strips. In addition to the
rectangular
construction, other embodiments of the supporting strip would also be
conceivable, whereby,
according to one useful possibility, the plastic profile has a triangular
shape, whereby it
forms a right-angle triangle which rests with the angle legs enclosing the
right angle against
the underside or extends parallel to the belt, and whereby the supporting
rollers are
constructed correspondingly. This design makes it possible to provide the
necessary settings
together with the pressure rollers. Depending on the positioning of the
triangle, it is now
even possible to completely eliminate the pressure rollers.
In particular, the pressure rollers can be completely eliminated if the
plastic profile is
shaped so as to correspond to the supporting rollers which are constructed as
diabolo rollers,
or if rollers and profiles have reversed shapes. This construction of the
supporting rollers or
supporting strips also provides the necessary settings in the direction of the
creeping of the
conveyor belt, which is now not only prevented from moving downward in
relation to the
angled position, but also from lifting from the supporting rollers. Pressure
rollers are
thereby no longer necessary.
It has been pointed out before that the conveyor belt cover and the plastic
profile are
constructed as a structural unit. But it would also be conceivable that they
are integrated into
the conveyor belt cover so that they can be produced and shaped simultaneously
with the
conveyor belt during its manufacture.
The necessary processing result is attained, as described above, by the
longitudinal
grooves, whereby it is useful that these longitudinal grooves be associated
with the conveyor
belt cover by providing the conveyor belt cover with a belt surface with a
glued-on groove
profile web. This has the advantage, similar to the case of the glued-on
supporting strips,
that standard conveyor belts can be used which are complemented with the
groove profile
web or also the supporting strips. This also makes it possible to attain the
exact construction
of the grooves and bridges more optimally, since a suitable rubber web can be
used.
The exact setting of the belt conveyor or conveyor belt cover requires, as
described
above, both the positioning of the supporting strips or supporting rollers,
and also that of the
pressure rollers. In order to ensure both a correct and quiet guidance of the
pressure rollers
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27026-38 ca o2l~oiso Zooo-ii-09
here, the invention provides that the conveyor belt cover is provided at the
edge and on both
sides with non-grooved roll-off surfaces. In this way, the pressure rollers
are rolling off in a
precisely guided manner on this roll-off surface or the bilateral roll-off
surfaces in order to
ensure the exact setting of the conveyor belt cover.
According to the invention at hand, the conveyor belt cover with its groove
profile
web has longitudinally extending grooves and lands, whereby the lands are
equipped with
angled sides and rounded free edges. The groove profile track has identically
constructed
grooves and lands over the entire width in order to achieve a constant
separating result.
During the transport over the length of the belt conveyor, the rougher
granules are able to
separate in time from the fine or finest coal over the angled sides and
rounded edges, and are
able to escape over the lower longitudinal side. Only the actually desired
finest granules
adhere inside the grooves and are safely discharged at the top, whereby
experiments have
shown that practically no outsize granules, or less than 10 % outsize
granules, remain in the
forest coal.
An optimum separation can be achieved in particular in that the conveyor belt
cover is
equipped with lands with an approximately 50 % smaller width at the free end
than on the
connection side, which has the additional advantage that the lands retain
sufficient setting on
the web or in the groove profile web.
The belt conveyor is an endless conveyor, whereby the conveyor belt cover is
guided
over two deflection rollers arranged at the ends, of which one is equipped
with a drive. In
order to prevent or mvaimize flexing inside the supporting strip or the
supporting strips, the
invention provides that the conveyor belt cover is guided in the area of the
deflection rollers,
for which purpose these are provided on the edges with recesses holding the
supporting
strips. In this way, the conveyor belt cover runs on the surfaces which
project further, while
the supporting strips engage somewhat deeper into the deflection rollers and
are also
su~ciently supported there. This largely counteracts flexing, whereby the
supporting strips
are possibly also divided into sections in order to reduce the flexing even
further, in
particular in the case of deflection rollers with a small diameter.
A division of the supporting strips into individual sections may, however,
result in
problems for the supporting strips and contribute to higher wear. To avoid
this while
facilitating the deflection of the supporting strips or conveyor belt cover,
the invention
provides that the conveyor belt cover is equipped with supporting strips which
are equipped
with spaced-apart cut-outs which taper off in arc-shape towards the center of
the conveyor
belt cover and leave a reinforcing land. This preserves a continuous support
surface for the
supporting rollers, while the supporting strips are able to move apart or
together in the
remaining area when running around the deflection roller. This creates an
optimum design.
In order to be able to produce conveyor belt covers with practically any
desired
width, and to do this at reasonable cost, the invention provides that the
conveyor belt cover
is equipped with a groove profile web composed of several interconnected
partial webs. This
4
27026-38 ca o2l~oiso Zooo-ii-09
creates double-width lands in the contact area of the individual groove
profile webs, which,
however, does not adversely affect the effectiveness of the entire conveyor
belt cover or the
belt conveyor in its entirety. .
In order to even out the tension of the conveyor belt cover or to ensure an
adequate
transmission of the drive forces, the conveyor belt cover can be tightened via
the deflection
rollers which are positioned adjustably in the support frame. This makes it
possible to
increase, e.g., the preload during longer operation, or the preload can also
be reduced if the
load on the conveyor belt cover is small.
It has already been pointed out above that it can be useful to adapt the tilt
or angled
position of the belt conveyor to the respective circumstances. In order to be
able to
accomplish this in a simple and useful manner, the invention provides that the
conveyor belt
cover with the support parts, as well as the deflection rollers and drives, is
associated with a
support bracket which is part of the support frame and is positioned with the
lower
longitudinal side via pivot joints in the support frame, and is held at the
upper longitudinal
side by adjustment devices. In this way, the tilt of the entire part of the
belt conveyor can be
adjusted evenly without risking that the conveyor belt cover receives or has a
different tilt at
some points. The entire support bracket is simply swiveled more or less around
the pivot
joint, and its tilt is adjusted.
It is useful that the adjusting devices are constructed as adjusting spindles,
whereby
the adjusting spindles can be associated with motors in order to ensure a
uniform adjustment
for several, longitudinally distributed, spindles in this manner or to
facilitate the adjustment.
Naturally, it is also conceivable that the adjusting devices be operated
manually.
As has already been mentioned repeatedly, the rough granules pass over the
individual
lands and are discharged via the lower longitudinal side of the conveyor belt
cover, i.e., onto
a rough granule conveyor extending there in the longitudinal direction of the
belt conveyor.
In order to be able to safely catch the rough granules rolling off, it is
hereby provided that
the lower longitudinal side of the conveyor belt cover is associated with an
adjustable guide
rail. These rough granules, in a manner of speaking, are guided by this guide
rail into the
rough granule conveyor or are guided in such a way that they do not move past
the rough
granule conveyor.
In the long run, perfect operation of such a classifier is only possible if
the forest
granules are also discharged at the return. This is accomplished in that the
return run of the
belt conveyor is associated with cleaning brushes which engage with the groove
profile web.
These cleaning brushes are rotated as a result of being driven by the belt
conveyor or are
provided with corresponding drives, and ensure that the individual grooves are
always kept
clean after the belt has passed the return, which is usually provided with a
drive.
27026-38 ca o2l~oiso Zooo-ii-09
A uniform cleaning of the individual grooves according to the invention is
also
improved, in that the cleaning brushes are arranged on a shaft which is
provided with a
drive. Several cleaning brushes can hereby be arranged on one shaft and can be
driven or
braked by the shaft; and it is also conceivable that several shafts with
cleaning brushes can
be provided in order to ensure safe cleaning in this way. The shaft drive in
this case can be
switched so that the shaft, and therefore also the cleaning brushes, run
slower than the belt
conveyor, thus improving the cleaning effect even more.
Instead of the supporting strips and mechanical support device, the invention
also
permits a solution according to which the conveyor belt cover is equipped on
the underside at
the edge with permanent magnets arranged so as to correspond with the coils
associated with
the carrying belt. This linear motor drive can be designed here in such a way
that it only
supports the conveyor belt cover. But it is also conceivable that all drive
forces are
generated via this linear motor drive, so that it would fulfill two functions.
Since both the
permanent magnets and the coils are located in the dust-free area, this makes
a continuous
operation of this kind easily possible.
A process for the dry classification of finest material provides, according to
the
invention at hand, that the conveyor belt cover is supported so as to roll at
the edge of the
upper longitudinal side during the circulation, that the circulation speed of
the conveyor belt
cover andlor the charged amount and/or the belt width and belt length and/or
the angled
position of the conveyor belt cover is varied in accordance with the granule
structure of the
charged material, and that the conveyor belt cover is supported and guided
uniformly, thus
resulting in a quiet run, from the underside over the entire length of the
belt conveyor.
Such a process results in an execution which can be adapted exactly to the
respective
charged material without requiring a special design. Rather, the respective
variation can be
implemented by the respective examination of the charged material, so that an
increasingly
more uniform classification result can be achieved. But a continuous operation
is made
possible by this process in particular, because the belt conveyor is kept in
the respective,
necessary angled position, so that in particular the simplest possible
adjustment can be
performed, namely the change in the tilt of the belt conveyor.
According to a useful further development, the invention provides that the
circulation
speed and/or the feed volume and/or the tilt of the conveyor belt cover and/or
the belt width
and belt length is varied in accordance with the difference in the specific
weight of the
charged material, so that such a classifier can finally also be used for
sorting. Because of
this, the versatility of the process and the installation according to the
invention are
enormously high, and it can be used both for coal and in other areas.
For optimum execution of the process according to the invention, i.e., the
exact
setting of the belt conveyor or the conveyor belt cover, it is provided that
the latter be
supported on the upper and lower longitudinal sides so as to be rolling. As
has already been
explained above, the rolling setting both defines and changes the necessary
tilt of the belt
6
27026-3 8
CA 02170150 2000-11-09
conveyor, and prevents in the case of an uneven load, an upward slipping or
upward
creeping of the conveyor at the lower longitudinal side.
The invention is characterized in particular in that this installation, i. e.
, the dry
classifier, eliminates the former high expenditure of processing the forest
material in the
jigging machines of a processing plant. The finest material is already
separated prior to
being introduced into the jigging machine, and thus need not be subjected to
the expensive
drying. The processing result can be greatly influenced by the possibility of
a speed change
and adjustment of the tilt and in the process in particular, can also be kept
uniform while
considering the respective charged material. The dry classifier is based
essentially on a belt
conveyor, which, however, has a special design, yet still represents in
principle a known
technology. Its advantage is that it can process large amounts of forest coal
or forest
material. The dry classifier is also resistant to malfunction, in particular
if the grooves are
continuously kept free with cleaning brushes.
Other details and advantages of the object of the invention are derived from
the
following description of the related drawings showing a preferred exemplary
embodiment
with the details and parts required for this purpose. In the drawing:
Figure shows a simplified illustration of a frontal view
1 of the dry classifier,
Figure shows a section through the conveyor belt cover with
2 the supporting
strips on the edges,
Figure shows a special design of the supporting strips,
3
Figure shows a section through the groove profile web,
4
Figure shows an enlarged portrayal of the edge area of a
conveyor belt cover
with supporting strip,
Figure shows a detail view of the support bracket holding
6 the essential parts of
the belt conveyor,
Figure shows the cleaning brushes associated with the return
7 run,
Figure shows a lateral view of the suspension of the cleaning
8 brushes,
Figure shows a longitudinal section through the deflection
9 roller which is not
driven,
Figure shows a section through the deflection roller which
is equipped with a
drive.
Figure 1 shows the entire installation of the dry classifier 1, whose core
part is the
tilted belt conveyor 2. This belt conveyor 2 is arranged in a support frame 3
which is
provided with several parts for supporting and guiding the conveyor belt cover
4.
The finest material is transferred to the conveyor belt cover 4 via the feed 6
which is
associated with the upper part of the conveyor belt cover 4. This feed area is
constructed as
a vibration screen 7. The rough material passes over the conveyor belt cover 4
and is
discharged via the lateral rough material discharge 8 and transferred to the
rough granule
conveyor 9. Precise guidance is provided by the guide rail 10 which can be
adjusted in its
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27026-3 8
CA 02170150 2000-11-09
tilt and its distance to the rough material discharge 8. An overflow guide 11
is provided on
the opposing side of the rough material discharge 8, since the rough granule
overflow from
the vibration screen 7 is, after all, also supposed to be picked up by the
rough granule
conveyor.
The belt conveyor 2 has an endless, guided conveyor belt cover 4, whereby the
classification is performed via the correspondingly designed carrying run 14,
while the return
run 15 is used to return the conveyor belt cover 4.
The underside 16 of the carrying run 14 or the top side of the return run 15
are
provided with supporting strips 17, i.e., at the upper longitudinal side 18,
and, additionally,
there are supporting strips 19 at the lower longitudinal side 20. These
supporting strips 17,
19 are, in particular, glued to the underside 16. The supporting strips 17, 19
support or hold
the conveyor belt cover 4, so that there is always a uniform belt surface 21
available for
holding or classifying the charged material. The support frame 3 is hereby
associated with
brackets 22, 23 which roll off the supporting strips 17 and 19 and which
ensure that the
conveyor belt cover 4 is both unable to slip in the direction of the lower
longitudinal side 20,
or can be pushed up in the direction of the upper longitudinal side 18,
especially in the case
of an uneven load. The supporting rollers 22, 23 hereby ensure that the
conveyor belt cover
4 remains in the respective, exactly specified position, even in the case of
an extreme tilt of
the belt conveyor 2. This applies both for the carrying run 14 and the return
run i5, which
is also associated with supporting rollers 22, 23' .
In order to avoid a bending up or running up and escaping of the edge of the
conveyor belt cover 4, pressure rollers 25 which run below covers 24 are
provided. Figure
1 here clarifies that additional pressure rollers 25' roll off the underside
of the return run 15.
Figure 1 clarifies that the belt surface 21 of the conveyor belt cover 4,
which will be
specified further in the following figures, can extend at the specified tilt
(15 - 45 °, preferably
35 °). Such a belt surface 26 makes it possible that the finest
material remains in the grooves
shown in Figure 2, while the rough granules roll past the respective lands
and, as already
mentioned, leave the actual belt conveyor 2 or dry classifier 1 at the lower
longitudinal side
20. The tilt of the belt conveyor 2 can be adjusted since the entire belt
conveyor 2, in a
manner of speaking, is associated with a support bracket 29, as shown in
Figure 6. This
support carrier, which, in a manner of speaking, holds the conveyor belt cover
4 and the
associated parts of the support frame 3 in order to be able to operate the
belt conveyor 2
accordingly, can be swiveled about pivot joint 30 which is located at the
lower longitudinal
side 20. The swiveling is hereby accomplished via an adjusting device 31
which, as is
shown in Figure 1 and Figure 6, can be lifted via a spindle or similar device,
whereby this
spindle can also be equipped with a drive, thus easily enabling motorized
adjustment. It is
useful that two or more such adjusting devices 31 are arranged over the
longitudinal side of
the belt conveyor 2.
8
CA 02170150 2000-11-09
27026-38
Figure 1 shows a section of a conveyor belt cover 4. It is hereby clear that,
according to Figure 2, the rubber profiles 33 which function as supporting
strips 17 or 19 are
positioned on the underside 16. These rubber profiles 33 reach up to the belt
edge 34 or
form an even edge together with the latter, both at the upper longitudinal
side 18 and the
lower longitudinal side 20.
According to Figure 3, the supporting strip 17, 19 or the rubber profile 33
may also
have a triangular shape, whereby the straight sides 35 of the angle enclosing
the right angle
are used, for example, to form a connection with the conveyor belt cover 4, or
are part of
forming the belt edge 34. The third side 36 of the triangle functions as a
roll-off surface for
the supporting roller 23.
Figure 2 and Figure 3 show that, contrary to the rubber profiles 33, the
actual
conveyor belt cover 4 has a belt 37 which is also equipped with a weave or is
provided with
similar reinforcements.
Figure 2 as well as Figures 4 and 5 clarify that a groove profile web 40 is
glued onto
the actual belt of the belt conveyor 2, which then forms the conveyor belt
cover 4. This
groove profile web 40 has on both longitudinal sides 18, 20 roll-off surfaces
41 for the
pressure rollers 25. This has already been pointed out in the explanation of
Figure 1.
Between these roll-off surfaces 41 are uniformly constructed grooves 42, 44
and lands
43, 45, whereby the lands 43, 45 are provided with angled sides 46, 47 and
rectangular
grooves, while the free edges 49, 50 of the lands 43, 45 are rounded. This is
especially
clear in Figures 4 and 5.
The special shape of lands 43, 45 results in a smaller width in the area of
the free
ends 51 of the lands 43 and 45, while on the connection side 48 a
corresponding widening of
the land 43 and 45 is achieved. This results in an adequate stiffness of these
lands 43, 45, in
spite of the relatively deep grooves 42, 44.
Figure 5 clarifies how the flexing in the area of the deflection rollers,
which will be
explained below, is reduced, for which purpose the individual supporting
strips 17, 19 are
provided with spaced-apart cutouts 54. These cutouts 54 are hereby constructed
so that a
support land 55 remains towards the center of the conveyor belt cover 4. For
this purpose,
the cutouts 54 extend in arc-shape towards the center of the conveyor belt
cover 4 and taper
off at a distance to the support edge of the supporting strip 17, 19. This
results in a
continuous roll-off track for the rolling-off supporting rollers 22 or 23, so
that wear can be
kept remarkably low.
Seen over the width of such a conveyor belt cover 4, it is useful that several
groove
profile webs 40 or corresponding partial webs 56, 57 are arranged, so that it
is also possible
to adapt the width of the conveyor belt cover 4 according to the requirements.
Partial webs
56, 57 each abut each other with one land, thus resulting in a kind of double
land 58.
9
27026-3 8
CA 02170150 2000-11-09
Figure 6 has been mentioned already. In addition, it should be pointed out
that for a
smooth, uniform guidance, even over longer belt conveyors 2, reinforcing
rollers 59 and 60
have been provided once for the carrying run 14 and once for the return run
15. In relation
to the reinforcing roller 59, a smaller width is provided in each case, so
that the supporting
strips 17, 19 constructed at the sides can be taken into account. Also shown
here is a
pressure roller 25 and the cover 24 associated with it. 61 designates a
support part, which
stands for the reinforcing rollers 59, 60 and the support rollers 22, 23, as
well as the
pressure rollers 25. This totality of supporting parts 61 ensures the precise
setting of the
conveyor belt cover 4 over the length of the belt conveyor 2.
Figure 7 shows the bottom part of the belt conveyor 2, where the cleaning
brushes
64, 65 acting on the returning run in order to clean the groove profile web 40
are shown.
The cleaning brushes 64[sic], 65 shown here are positioned on a common shaft
66 and thus
rotate uniformly or, depending on the construction, also at a different speed,
whereby the
latter depends on the speed of the conveyor belt cover 4. It is however also
conceivable that
the shaft 66 is braked, so that the bristles 67 of the cleaning brushes 64, 65
perform a
specific cleaning action. But usually an unbraked design is adequate.
According to Figure 8, two or even three cleaning brushes 64, 64' are
positioned as a
compact cleaning unit, whereby, e.g., additional cleaning brushes can be
positioned on the
center shaft 66, resulting in a compact cleaning unit which is practically and
safely connected
to the support frame 3.
Figures 9 and 10 show the deflection roller 68 without drive, and the
deflection roller
69 with drive 70, whereby both are provided on the edge with recesses 71, 72
on which the
supporting strips 17, 19, which are not shown here, support themselves when
turning about
the deflection rollers 68, 69.
The deflection rollers 68, 69 are provided with a coating 73 which is supposed
to
promote a uniform transmission of the drive forces, especiaily in the area of
the deflection
roll 69 shown in Figure 10.
All mentioned characteristics, including those which can be derived only from
the
drawings, are considered to be essential to the invention both by themselves
and in
combination.
