Note: Descriptions are shown in the official language in which they were submitted.
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ROLLER CRUSHER HAVING AT LEAST ONE ROLLER COMPRISING A
FLANGE
This application is a divisional of Canadian Patent Application No. 2,870,044,
filed on April 19, 2013.
Technical field
The invention relates to a roller crusher having two generally parallel
rollers arranged to rotate in opposite directions, towards each other, and
separated by a gap, each roller having a first end and a second end.
Background art
When crushing or grinding rock, ore, cement clinker and other hard
materials roller crushers may be used having two generally parallel rolls
which rotate in opposite directions, towards each other, and which are
separated by a gap. The material to be crushed is fed by gravity or choke-fed
into the gap. One type of roller crusher is called high pressure grinding
rollers
or high pressure roller crushers. This type of roller crusher uses a crushing
technique called interparticle crushing. Here, the material to be crushed or
pulverised is crushed not only by the crushing surface of the rolls, but also
by
particles in the material to be crushed, hence the name interparticle
crushing.
One example of a high pressure grinding roller is described in
EP-516 952. The document discloses an improved roll for a roller press
capable of withstanding very high nip forces in a press nip for interparticle
crushing. The roller press has a plurality of spaced wear-resistant surface
members embedded in the pressing surface of the roll which are of a material
harder than the material of the roll surface surrounding the inserts. By
varying
the size and number and material properties of the embedded pieces, the
wear of the press roll is matched to the materials to be comminuted to
minimize wear and to match the wear profile along the roll with extended
pressing use.
A general problem associated with existing high pressure grinding
rollers is that the ratio between the roller diameter and the roller width is
very
important due to a significant edge effect, i.e. the crushing result is
reduced at
the edges of the rollers. This is because of the fact that material can escape
over the edges of the rollers thereby reducing the crushing pressure on the
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material towards the gap at the edges of the rollers. Thus, these roller
parameters cannot be varied to the desired extent.
Summary of the invention
It is an object of the present invention to provide an improvement of the
prior art. More particularly, it is an object of the present invention to
provide a
roller crusher for which the roller diameter and the roller width can be
varied
more freely without a reduced crushing result.
These and other objects as well as advantages that will be apparent
from the following description of the present invention are achieved by roller
crusher according to the independent claims.
A roller crusher having two generally parallel rollers arranged to rotate
in opposite directions, towards each other, and separated by a gap is
provided. Each roller has a first end and a second end. The roller crusher
comprises a flange attached to at least one of the ends of one of the rollers.
The flange extends in a radial direction of the roller, and has a height above
an outer surface of the roller which is sufficient to extend across the gap
substantially along a nip angle of the roller crusher. This is advantageous in
that the flange eliminates the weakness spot at the edge of the rollers. The
flange will help maintaining the material on the outer roller surface. That is
to
say, due to the flange, the material is prevented from falling over the edge
of
the roller. This will in turn help increasing the pressure on the material
towards the gap between the rollers at the edge of the rollers. By eliminating
the weakness spot at the edge of the rollers, the roller diameter and the
roller
width can be varied more freely without a reduced crushing result.
Additionally, the flanges will facilitate the providing of an autogenous
protection layer on the rollers, consisting of the material to be crushed.
The height may be sufficient to extend across the gap substantially
along a nip angle of the roller crusher, when the gap is set to a maximum
operational gap. The advantages mentioned above will thus be achieved at
the most critical moment of the crushing operation.
The flange may comprise a feeding structure on the inside of the
flange, said structure extending from the inside of the flange towards the
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other end of the roller. This is advantageous in that the structure will help
increasing the pressure on the material towards the gap between the rollers
at the edge of the roller even further. The structure will engage with the
material which will be moved inside the crushing area and the pressure will be
optimized.
The structure may be arcuate, continuous, intermittent, or a
combination thereof. These are preferred embodiments of the structure.
The flange may be made of a first material and the structure of a
second material, said second material being harder than said first material.
This way, the structure will act as a wear-resistant element and protect the
flange from wear. The structure will also help creating and holding an
autogenous protection layer on the flange.
The flange may be divided into a plurality of segments, which is
advantageous in that both the manufacturing and mounting of the flange will
be facilitated. The flange may be attached to the roller by means of adhesive,
bolting, screwing, welding, brazing or any other suitable fastening technique.
The roller crusher may comprise a flange attached to each end of one
of said rollers, respectively. The advantages mentioned above will thus be
achieved on both ends of the roller.
Generally, all terms used in the claims are to be interpreted according
to their ordinary meaning in the technical field, unless explicitly defined
otherwise herein. All references to "a/an/the [element, device, component,
means, etc]" are to be interpreted openly as referring to at least one
instance
of said element, device, component, means, etc., unless explicitly stated
otherwise. Further, by the term "comprising" it is meant "comprising but not
limited to" throughout the application. Lastly, the "nip angle" is defined as
the
angle between the horizontal plane extending through the centre of a first and
a parallel second roller, and a straight line which is drawn from the centre
of
the first roller to and through a point on the parallel second roller, at
which
point an active engagement between the second roller and the material to be
crushed is started. In the literature concerning this subject, two different
nip
angles are provided. One nip angle concerns single particle crushing, and
one nip angle concerns interparticle crushing. The nip angle concerning
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interparticle crushing is obviously smaller than the nip angle concerning
single
crushing. Note that, in the present application, the nip angle concerning
interparticle
crushing is intended.
In some embodiments of the present invention there is provided a roller
crusher
having two generally parallel rollers arranged to rotate in opposite
directions, towards
each other, and separated by a gap, each roller having a first end and a
second end,
said roller crusher comprising: a flange attached to at least one of said ends
of one of
said rollers, said flange extending in a radial direction of said roller, said
flange having
a height above an outer surface of said roller which is sufficient to extend
across said
gap substantially along a nip angle of said roller crusher, wherein said
flange
comprises a feeding structure on an inside of the flange, said feeding
structure
extending from the inside of the flange towards the other end of the roller.
Brief description of the drawings
The above, as well as additional objects, features and advantages of the
present invention, will be better understood through the following
illustrative and
non-limiting detailed description of preferred embodiments of the present
invention,
with reference to the appended drawings, where the same reference numerals
will be
used for similar elements, wherein:
Fig. 1 is a perspective view of a roller crusher according to one exemplary
embodiment of the invention,
Fig. 2a is a perspective view of a roller of the roller crusher having two
flanges
extending in a radial direction of the roller,
Fig. 2b is a perspective view of a segment of one of the flanges in Fig. 2a,
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Fig. 3a is a perspective view of a roller of a roller crusher having two
flanges extending in a radial direction of the roller,
Fig. 3b is a perspective view of a segment of one of the flanges in Fig. 3a,
Fig. 4a is a perspective view of a roller of a roller crusher having two
flanges
extending in a radial direction of the roller,
Fig. 4b is a perspective view of a segment of one of the flange in Fig. 4a,
and
Fig. 5 is a side view of the roller crusher in Fig .1, when having one flange
only.
Detailed description of preferred embodiments of the invention
Fig. 1 illustrates a roller crusher 1 according to one exemplary embodiment of
the invention. The roller crusher 1 has two generally parallel rollers 2
arranged to
rotate in opposite directions, towards each other, and are separated by a gap.
Each
roller 2 has a first end 3 and a second end 4. The roller crusher 1 comprises
a
flange 5 attached to the first and second end 3, 4
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of one of the two rollers 2 of the roller crusher 1. The flanges 5 extend in a
radial direction of the roller 2 and have a height H above an outer surface 6
of
the roller which is sufficient to extend across the gap substantially along a
nip
angle a of the roller crusher 1. The height H is sufficient to extend across
the
5 gap substantially along a nip angle a of the roller crusher 1 when the
gap is
set to a maximum operational gap. The flanges 5 are plain and will help
maintaining material to be crushed on the outer roller surface 6. That is to
say, due to the flanges 5, the material is prevented from falling over the
edge
of the roller 2. The flanges will also facilitate the providing of an
autogenous
protection layer on the rollers, consisting of the material to be crushed. The
flanges 5 are divided into a plurality of segments 7 in order to facilitate
the
manufacturing and mounting of the same. The flanges 5 are, for example,
attached to the roller 2 by means of adhesive, bolting or screwing.
In Fig. 2a, the roller 2 of the roller crusher 1 having a flange 5 on each
end 3, 4 and extending in a radial direction of the roller 2 is illustrated.
The
flanges 5 are plain and will eliminate the weakness spot at the edge of the
rollers 2. The flanges 5 will help maintaining the material on the outer
surface
6 of the rollers 2 and prevent the material from falling over the edge of the
roller 2. This will in turn increase the pressure on the material towards the
gap
between the rollers 2 at the edge of the rollers 2.
Fig. 2b illustrates a segment 7 of the flange 5 in Fig. 2a. As stated
above, the flanges 5 are divided into segments 7 in order to facilitate the
manufacturing and mounting of the same. However, the flanges 5 can
naturally be designed as one single unit.
In Fig. 3a, a second embodiment of the roller 2 of the roller crusher 1 is
illustrated. Here, the flanges 5 comprise a feeding structure 8 on the inside
of
the flanges 5. The structure 8 extends from the inside of the flange 5 towards
the other end 3, 4 of the roller 2. The structure 8 is continuous and arcuate.
The structure 8 will increase the pressure on the material towards the gap
between the rollers 2 at the edge of the roller 2. The material will engage
with
the structure 8 and be pressured towards and through the gap, i.e. the
material will be choke-fed into the gap.
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Fig. 3b illustrates a segment 7 of the flange 5 in Fig. 3a. Naturally, also
the flanges 5 according to this second embodiment can be designed as one
single unit.
In Fig. 4a, a third embodiment of the roller 2 of the roller crusher 1 is
illustrated. Here, the flanges 5 also comprise a feeding structure 8 on the
inside. However, the structure 8 according to this embodiment is intermittent.
Fig. 4b illustrates a segment 7 of the flange 5 in Fig. 4a. Naturally, also
the flanges 5 according to this third embodiment can be designed as one
single unit.
In Fig. 5, a side view of the roller crusher 1 is illustrated in order to
facilitate the understanding of the nip angle a. A first straight line has
been
drawn from the centre of the right roller 2 to and through a point on the left
roller 2, at which point an active engagement between the left roller 2 and
the
material to be crushed is started. The nip angle a is measured between the
horizontal plane extending through the centre of the left and right roller,
and
said first straight line. It is the smaller of the two possible angles which
can be
obtained in accordance with the definition presented above. In the
embodiment illustrated in Fig. 5, the height H of the flange 5 above the outer
surface 6 of the roller 2 is sufficient to extend across the gap substantially
along the nip angle a of the roller crusher 1.
During the crushing operation of the roller crusher 1, the material to be
crushed is transported to the roller crusher 1 by means of a feeding
arrangement and is introduced into a funnel of the feeding arrangement. The
material to be crushed is then fed to the gap between the two rollers 2 of the
roller crusher 1. The flange 5 of the roller crusher 1 will help maintaining
the
material on the outer roller surface 6 of the rollers 2 and help increasing
the
pressure on the material towards the gap between the rollers throughout the
width of the rollers 2, especially at the edge of the rollers 2. When the
material
has been crushed by means of the two parallel and rotating crushing rollers 2,
it travels by gravity out of gap in order to be transported from the unit.
The invention has mainly been described above with reference to a few
embodiments. However, as is readily appreciated by a person skilled in the
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art, other embodiments than the ones disclosed above are equally possible
within the scope of the invention, as defined by the appended claims.
For instance, the structure may be of any suitable size and shape, for
example straight, inclined, curved, ring shaped, double or single.
The size and shape of the flanges may also be varied to include a
plurality of structures. If the flanges comprise a plurality of structures,
these
structures may be of different size and shape.
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