Abstrict The invention relates to a multi-roller crusher for the comminuting
of mineral mill-feed, whereby the crushing roll are provided with
crushing teeth, extending in the circumferential and longitudinal
axial directions. Viewed in plan, the crushing teeth are arranged
on each crushing roller such that several serial crushing teeth
groups are formed behind each other, the imagined connection lines
of which run successively at an inclined angle to the plan (1',2')
of each crushing roller outer edge in the direction of the crushing
roller centre.
Claims The invention claimed is:
1. A multi-roller crusher for comminuting mineral material to be
crushed comprising two juxtaposed counter rotating crushing rollers
receiving lumps of mineral material to be crushed between them,
the crushing rollers being provided with radially projecting individual
and discrete crushing teeth spaced apart both in a peripheral direction
and in a circumferential and longitudinal axial, direction in a
developed view of each crushing roller in plan view, the crushing
teeth are so arranged that they form a plurality of successive crushing
tooth groups, whose imaginary connection lines at a presettable
angle of inclination in relation to the developed view, extend towards
one another from a respective outer edge of the crushing roller
in the direction of a crushing roller center, the adjoining and
opposite crushing teeth of the crushing tooth groups defining in
an intake region between the counter-rotating crushing rollers continuously
repetitive, primary crushing chambers, the imaginary connection
lines of the crushing tooth groups of each crushing roller, in relation
to the developed view being so oriented towards one another that
arrows are formed, which are oriented towards one another.
2. The multi-roller crusher according to claim 1 wherein the imaginary
connection lines of the individual crushing tooth groups are straight
lines.
3. The multi-roller crusher according to claim 1 wherein the imaginary
connection lines of the individual crushing tooth groups are curves
with presettable curvature.
4. The multi-roller crusher according to claim 1 wherein the individual
crushing tooth groups of each crushing roller are arranged essentially
in mirror-image in relation to one another.
5. The multi-roller crusher according to claim 1 wherein the imaginary
connection lines of the individual crushing tooth groups extend
toward one another at unequal angles of inclination.
6. The multi-roller crusher according to claim 1 wherein the ratio
between the outer roller diameter and the tooth height is 5:1 the
number of teeth in the peripheral direction of each crushing roller
(1 2) being between four and nine teeth.
7. The multi-roller crusher according to claim 1 wherein the crushing
rollers are driven synchronously by a drive mechanism.
8. The multi-roller crusher according to claim 1 wherein one of
said crushing rollers is provided to serve as a master roller, while
the other crushing roller for approximate synchronization or crushing
roller positioning is subjected to a control system for fine adjustment
in relation to said one crushing roller.
9. The multi-roller crusher according to claim 1 wherein the crushing
rollers are driven asynchronously in order to attain an optimal
differential velocity.
10. The multi-roller crusher according to claim 9 independent drives
are assigned to each crushing roller.
11. The multi-roller crusher, defined in claim 9 wherein the differential
velocity of the crushing rollers is controlled or adjusted by at
least one frequency converter, a hydraulic drive or a mechanical
step-down gear unit.
Description CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national stage of PCT/EP02/03666 filed 3
Apr. 2002 and is based upon German national application 101 20 765.4
of 27 Apr. 2001 under the International Convention.
FIELD OF THE INVENTION
The invention relates to a multi-roller crusher for comminuting
mineral material to be crushed, the crushing rollers being provided
with radially projecting crushing teeth, extending both in the circumferential
and longitudinal axial directions.
BACKGROUND OF THE INVENTION
The practically viable methods of comminution differ by is the
type of stress or deformation of the particles to be comminuted
in the crushing chamber. When stressing the particles between two
roller surfaces, pressure, shear and tensile stresses are generated
in the particles. The design of the roller surface as well as the
rate of rotation determine the type of stress and the intensity.
U.S. Pat. No. 3240436 describes a crushing apparatus for solid
materials. In this case glass products, such as television tubes
or the like are regarded as solid materials.
The counter-rotating crushing rollers are driven synchronously
by way of a joint drive mechanism and comprise crushing teeth in
the form of annular gears and arranged in the peripheral and longitudinal
axial directions. The cross-section through each crushing roller
shows a plurality of crushing teeth per annular gear so that in
the region where the individual crushing teeth of the two crushing
rollers comb with one another relatively small crushing chambers
are formed in the entry region above the crushing rollers. It is
shown that even relatively large glass products may be gripped by
the teeth and are pre-crushed in the course of a first crushing
process. As the crushing gap of the counter-rotating crushing rollers
further decreases, a second, subsequent comminution is performed.
EP-B 0 167 178 describes a mineral crusher comprising two crushing
rollers, each of them equipped with a number of mineral crusher
teeth projecting radially from the roller, the teeth on each roller
being arranged in groups, extending in peripheral direction, spaced
axially along the roller, the groups of teeth extending in peripheral
direction being so arranged on a roller that they are positioned
between adjoining groups of teeth of the other roller, extending
in the peripheral direction and being axially spaced apart from
them, so that in the event of counter-rotation of the rollers the
teeth of the individual groups pass between two axially spaced teeth
in adjoining groups of teeth on the other roller, seizing in the
course thereof mineral lumps between one another, effecting the
breaking up or crushing of the said lumps. The teeth of each roller
are so arranged in relation to one another and are of such size
and shape that they define a number of discrete, peripherally spaced,
spiral or helical configurations extending along the roller. Each
roller includes therefore tooth formations extending spirally from
one end to the other, in which context the helix may run in the
same or in the opposite direction. The object and purpose of the
spiral or helical configuration of the crushing teeth is based on
transporting the material to be comminuted in the longitudinal direction
of the crushing rollers and in comminuting the former during transport.
However, an arrangement of the spiral or helical tooth formation
in the same direction would in this case be non-sensical, as no
defined transport can be performed. This is only possible when the
helices are arranged counter-directionally.
A mineral crusher designed in this manner comprises relatively
few teeth per annular gear, viewed in the peripheral direction,
so that with counter-rotating rollers a larger crushing chamber
is formed already, serving to comminute larger lumps as well. However,
it is a drawback of this mineral crusher that the material to be
crushed must be fed essentially from the end face side in order
to exploit the transport effect, thereby causing various conditions
of wear--even when considering the transport of the material in
the longitudinal direction of the rollers.
If the material were to be fed elsewhere than at the end, transport
would take place, but it would not be optimal and it would be undefined.
The present invention is based upon the state of the art as established
by EP 0 167 178 i.e. by a slow running double roller crusher. Such
machines are used both for the comminution of medium-hard rock as
well as for materials with a tendency to cake, i.e. brown and hard
coal, limestone, clay marl and similar raw materials. Parallel and
counter-rotating crusher rollers are equipped--as set out in the
characterising part of the first patent claim--with crushing teeth,
the size, shape and configuration of which define, during the interaction
of both rollers, a crushing chamber, ensuring the required quality
of the discharge particle size and the throughput performance during
comminution.
OBJECTS OF THE INVENTION
It is an object of the invention to optimize the multi-roller crusher
described in the PREAMBLE of the first patent claim of EP 0 176
178 in such a manner that, in contrast to EP 0 176 178 due to the
formation of simultaneously effective primary crushing chambers
substantially more large-grained lumps may also be comminuted parallel
and effectively in less time, in order, thereby, to attain an increase
of the effective comminution output. Wear should occur uniformly
across the length of the roller, with regard to the serviceable
life of the multi-roller crusher.
SUMMARY OF THE INVENTION
This object is attained in that when viewing the developed view
of each crushing roller in plan view, the crushing teeth are arranged
on each crushing roller such that they form a plurality of successive
crushing teeth groups, the imaginary connection lines of which,
at a presettable angle of inclination in relation to the plan view,
extend towards one another from each crushing roller outer edge
in the direction of the crushing roller center.
The invention therefore is a comminuting apparatus, whose crushing
rollers are equipped with a small number of large tooth formations,
viewed over the periphery. The ratio between the outer diameter
of the roller and the tooth height should in this case be less than
5:1 in which context the number of teeth, seen in the peripheral
direction of each crushing roller, should be small, e.g. limited
to nine teeth.
The fewer teeth are present over the periphery, uniformly spaced
from the center, and over the outer diameter of the crusher rollers
and the lower the peripheral velocity and therefore the tooth engagement
frequency, the more aggressively the roller surface acts on the
material to be fed, ensuring effective material intake. Because
of the small basic diameter of the crushing rollers in relation
to the center distance, the tooth height and an axial tooth separation,
in the case of this type of crushing chamber design, relatively
large free spaces are created between the adjoining and opposite
crushing teeth in the region between the crushing rollers. In particular,
due to the mutually facing arrow configuration, viewed in the longitudinal
direction of the rollers, two successive primary crushing chambers
of approximately the same size are formed. The person skilled in
the art considers the continuous formation of deep three-dimensional
troughs for the entry of large material lumps on the roller surfaces
as primary crushing chambers.
The actual comminution process of larger material lumps commences
in this case with positive material feeding. The material lumps
are seized between two or more corresponding crushing teeth of the
crushing rollers and undergo a first size reduction. With further
rotation of the crushing rollers the combing of the corresponding
teeth formations brings about the formation of secondary crushing
chambers, in which the pre-crushed or smaller material is clamped
and is locally stressed under bending and shearing action. In this
step the comminution is performed between the crushing teeth diameter
and the basic diameter of the crushing rollers, or, respectively,
between the tooth front and the tooth back of the opposing crushing
roller.
To that extent the type of comminution is to be considered analogous
to that described in EP 0 167 178. However, in contrast to the state
of the art, in the sense of momentary views taken over the length
of the roller, large intake regions are brought about either simultaneously
one behind the other or continuously forming anew, so that in this
case, contrary to the state of the art, a substantially higher portion
of coarse material may be pre-crushed, which considerably increases
the effective comminution output. In view of the fact that, contrary
to the state of the art, material transport is now brought about
on both sides, intake of the material to be crushed may now take
place centrally from above, i.e. directly into the developing larger
crushing regions. Wear of the multi-roller crusher according to
the invention, viewed over its length, is substantially more uniform
in comparison with the state of the art, which may also increase
the useful life.
In addition, subsequent comminution may optionally take place below
the central crushing gap in that a crusher beam, known per se is
provided, combining the function of an anvil or comb.
Essential factors for effective comminution with high throughput
performance by reducing the comminution time for large material
lumps are seen in the following points Peripheral velocity Tooth
configuration or distribution Tooth arrangement Positioning of rotor
In the developed view the successively arranged crushing tooth
formations comprise, as imaginary connection lines, straight lines
or bends with predeterminable curvature.
However, an essential difference in contrast to the state of the
art according to EP 0 17 178 is that for each crushing roller successive
mutually facing crushing tooth groups are formed, which ideally,
i.e. in the case of a rectilinearly proceeding imaginary connection
line, result in arrows oriented towards or away from one another.
The uniform crushing tooth formations over the periphery (annular
gear) in the case of the multi-roller crusher according to the invention
are arranged axially in relation to one another on a crushing roller
at a particular offset-angle, so that, viewed spatially, two counter-oriented
tooth rows are formed, which in the event of an uneven number of
annular gears have their vertex in the region of the central annular
gear of each crushing roller. In the event of an even number of
annular gears there exists no central annular gear, so that the
vertex will be formed differently. The corresponding opposite crushing
roller is equipped with the same tooth arrangement, viewed over
its length. In plan view onto the crushing rollers in operation
an arrow-like configuration extending in opposite direction thus
comes about, subdividing the overall roller length into two large
regions of about the same size.
A further development of the invention may provide that the imaginary
connection lines of the crushing teeth of each crushing roller are
provided in relation to one another appropriately set off in relation
to one another. In this particular arrangement the uniform crushing
tooth formations are arranged axially in relation to one another
on a crushing roller at a particular offset-angle over the periphery
(annular gear), such that when viewed spatially, two rows of teeth
are formed facing in opposite directions, which, offset by a predeterminable
angle of circumferential pitch, extend towards one another. The
matching opposite roller is equipped with the same tooth arrangement,
viewed over the roller length. In practical use, when viewed in
plan view of the crushing rollers, an offset arrow configuration
is brought about extending counter-directionally, subdividing the
overall roller length into two regions of approximately equal size.
This arrangement differs from the first one mentioned above in
that the intake regions developing during operation in the course
of combing of the counter-rotating crusher rollers are not formed
simultaneously, but successively. By way of this configuration the
object of a continuous comminution process/force concentration may
even be realized in the case of smaller crushing roller lengths
comprising a smaller number of teeth/circumference.
Therefore, in contrast to the state of the art, a continuous formation
of a plurality of deep, three-dimensional, primary crushing chambers
is brought about for the simultaneous entry of large material lumps.
For the development of primary crushing chambers crushing rollers
are advantageous, which rotate approximately synchronously. This
is achieved by mechanically coupling the crushing rollers, but has
to be regarded as complex, since the crusher housing corresponds
to the gear housing. In this context a double or single drive mechanism
may be used. In order to realize this approximately synchronous
roller rotation without mechanical connection, it is possible to
equip both rollers with independent drive means and to provide them,
for example, with a master slave control, permitting precise roller
timing.
A further parameter for optimizing the primary crushing chamber-design
is seen in driving the crushing rollers asynchronously. In this
case an independent drive means may be assigned to each crushing
roller or a single drive mechanism comprising a mechanical step-down
gear unit may likewise be employed. The optimal differential velocity
of the crushing rollers for a high incidence of primary crushing
space formation may, for example, be controlled or set by a frequency
converter or hydraulic motor. The optimal differential velocity
depends in this case on the process-technological task to be completed
and the number of teeth over the circumference.
Both in the case of the advantageous arrow-shaped configuration
as well as in the case of the crushing tooth groups, provided in
an offset manner in relation to one another, a distribution function
is performed on both sides from the center of the crushing chamber
in order to exploit the overall width of the crushing roller by
axial force components, especially in the case of larger sized material
lumps. The material is fed to the comminution apparatus, controlled
by a feeding conveyor, in which context the feed direction may be
transverse to the longitudinal direction of the rollers. The point
of impact of the discharge parabola may be set between the counter-rotating
crushing rollers as target-oriented as possible. This arrangement
avoids power- and wear-intensive deflecting and lifting of the material
flow. In particular, the fine content in the feed material may be
put through directly and with the lowest resistance and dwell time
possible, using as large as possible a passage cross-section over
the length of the roller.
BRIEF DESCRIPTION OF THE DRAWING
The subject of the invention is shown by way of a working example
in the drawing and is described as follows. In the drawing:
FIGS. 1 and 2 are schematic diagrams of counter-rotating crushing
rollers of a multi-roller crusher, not shown in detail, as well
as their developed views;
FIGS. 3 and 4 are schematic diagrams of alternative embodiments
of crushing rollers as well as their developed views;
FIG. 5 is a plan view of the installed crushing rollers according
to FIGS. 1 and 2;
FIG. 6 is a side elevation of the installed crushing rollers according
to FIGS. 1 and 2;
FIGS. 7 to 9 are different spatial illustrations (according to
FIGS. 1 and 2) of different momentary views for generating enlarged,
successive crushing chamber regions
FIGS. 10 and 11 are schematic diagrams of tooth formations on crushing
rollers as an alternative to FIGS. 1 to 4;
FIGS. 12 to 14 are different spatial illustrations (according to
FIGS. 10 and 11) of different momentary view for generating enlarged,
successive crushing chamber regions;
FIG. 15 is the developed view of an arrow-shaped tooth formation
with an even number of annular gears and different pitches;
FIG. 16 is the developed view of an arrow-shaped tooth formation
with an even number of annular gears and even pitch;
FIG. 17 is the developed view of a curve-like tooth formation;
and
FIGS. 18 and 19 are momentary views during asynchronous operation
of the crushing rollers forming primary and secondary crushing spaces.
SPECIFIC DESCRIPTION
In the form of schematic diagrams FIGS. 1 and 2 show counter-rotating
crushing rollers 12 of a multi-roller crusher not shown in detail.
FIG. 1 shows the crushing rollers 12 in their normal state, while
FIG. 2 illustrates the crushing rollers 12 in their developed view
1',2'. The indicated dots define crushing teeth 33',44'. It is
apparent both from the crushing rollers 12 shown in FIG. 1 as well
as from their developed view 1',2' that the imaginary lines 55',66'
interconnecting the crushing teeth 331441 extend on each crushing
roller 12 in such a manner that successive arrows are formed. The
crushing teeth 33',44' of each crushing roller 12 form crushing
tooth groups A,B,C,D, in which case the crushing teeth 33',44'
of each crushing tooth group A,B,C,D extend from the respective
outer edge 1a,2a,1b,2b of the crushing roller in the direction of
the center X-Y of the crushing roller. The uniform crushing tooth
formations over the circumference (annular gear) are in this crushing
roller arrangement offset axially in relation to one another on
the crushing roller 1 at a special offset angle, such that, when
viewed spatially, two rows of teeth are formed facing in opposite
directions, having their vertex in the region of the central annular
gear 7 of the crushing roller 1. The corresponding opposite crushing
roller 2 comprises the same tooth arrangement, viewed over the length
of the roller, in which case the tooth rows 66' (imaginary connection
lines) have their vertex in the region of the associated central
annular gear 7'. Viewing the crushing rollers 12 or their developed
views 1',2' in plan view, a counter-directional arrow configuration
AB;CD thus forms, dividing the overall roller length into two uniform
regions, as shown in more detail in FIGS. 7 to 11. In FIGS. 1 and
2 the arrows formed in this manner are directed towards one another.
In the examples the imaginary connection lines 55',66' are rectilinear,
while curved designs of the protection region are likewise included
(FIG. 17), without departing from the arrow configuration.
FIGS. 3 and 4 show an alternative to FIGS. 1 and 2 in which case
the imaginary connection lines 55' as well as 66' are likewise
so arranged in relation to one another that arrows AB;CD directed
away from one another are formed. The uniform arrangement of the
crushing teeth 33',44', viewed over the circumference (annular
gear), results in two counter-oriented rows of teeth 55',66',
viewed spatially, having their vertexes in the region of the central
annular gear 77' of each crushing roller 12 or, respectively
its developed view 1',2'. For the remainder, the structure of the
crushing tooth groups A,B,C,D is be considered analogous to that
according to FIGS. 1 and 2.
FIG. 5 shows the plan view of a multi-roller crusher 10 according
to FIGS. 1 and 2. Identical components are denoted by identical
reference numerals. The crushing rollers 12 can be seen housed
inside a housing 11. The crushing rollers 12 are to be driven in
counter-direction to one another (see arrows). Annular gears 1213
are apparent, to which the crushing teeth 34 are replaceably fitted.
FIG. 5 is a momentary view of successively positioned, continuously
repetitive crushing chambers, in which context in the present example
the primary crushing chamber B1 can be seen, formed by the imaginary
connection line 56 extending along the crushing teeth 34.
FIG. 6 shows a side elevation of the multi-roller crusher 10 where
the annular gears 1213 carrying the crushing teeth 34 can be seen
with the crushing teeth 34 arranged in offset relationship to
one another when viewed in the longitudinal direction of the crushing
rollers 12. Furthermore the housing 11 surrounding the crushing
rollers 12 can be seen. In the present example, each crushing roller
12 comprising 4 crushing teeth 34 per annular gear 1213 so that
the arrow-shaped profile shown in FIGS. 1/2; 3/4 is brought about.
FIGS. 7 to 9 show different perspective illustrations of momentary
views of the multi-roller crusher 10 with an arrow-shaped tooth
arrangement. This is done with regard to the continuously changing
crushing chambers B1 B2 B3. In this case as well, the same reference
numerals denote identical components. The two crushing rollers 12
are shown, the annular gears 1213 positioned thereon as well as
the crushing teeth 33',44' provided thereon. The crushing rollers
12 are arranged inside the housing 11 in which context the crushing
teeth 33',44' may be passed between formations 1415 on the side
of the casing. The formations 1415 have a particular configuration
and are designed like a comb. It is their function to deflect the
material fed to the crushing chamber directly to the central crushing
gap, without causing the material to be raised in counter flow.
Moreover, they serve as means to avoid oversized particles, since
they ensure compliance with the separation size diameter in the
side regions. In addition, they exercise a stripping function, in
order to protect the space between the annular gears from caking
materials. The parameter to be allocated to the crushing spaces
B1 B2 B3 is recognizable by way of the imaginary connection lines
55',66' and illustrates--as already mentioned--merely a momentary
view.
FIG. 7 shows an opened-up design of the roller surface, i.e. a
deep three-dimensional trough B1 for receiving large material lumps
entering there. As a result of the arrow-shaped arrangement of the
crushing teeth 33',44' in conjunction with the given, momentary
roller positioning (gripping position) oblong material lumps may
come to lie in the trough B1 deepening over the entire roller length
towards the center. Because of the rebating on both sides of the
corresponding central tooth pair 77' of both crushing rollers 12
high comminution efficacy is attained. The less mutual interference
there is between the adjoining teeth 33',44' and the tooth pair
77', the more favorable is the intake performance. In the state
of the art according to EP 0 167 178 a rebating exists only on one
side over the roller length of the crushing teeth. In the course
of further rotation of the crushing rollers further primary crushing
chambers B2 B3 (FIGS. 8 and 9) develop. If the material lump in
the primary crushing chamber B1 has not yet been adequately comminuted,
it is conveyed into a forced position axially towards the exterior,
defined by the respective housing side walls as well as the crushing
chambers B1 B2 and the axial force components, exercised by the
tooth formations onto the lumps. In these crushing chambers B2
B3 the further primary comminution is performed. In the state of
the art only a single primary crushing chamber is formed on the
roller surface due to the helical arrangement of the crushing teeth
over the roller surface. Any larger sized material lumps remaining
at the end of the crushing rollers opposite the end face feeding
are therefore merely conveyed into a single forced position, formed
by the associated housing side panel. As a result of the frequency
of the developing primary crushing chambers B1 B3 the effective
primary comminution throughput is substantially increased as compared
with the state of the art. The material is transported less until
comminution takes place, resulting in faster comminution and lower
wear.
FIGS. 10 and 11 as schematic diagrams, show an alternative embodiment
of the tooth groups A,B,C,D in the region of the crushing roller
12 as their respective developed views 1',2'. FIG. 11 shows crushing
teeth 331441 forming successively positioned tooth groups AB;CD,
in which case the imaginary connection lines 55',66' extend towards
one another, but do not form an ideal arrow, but an offset arrow
configuration. In this example the imaginary connection lines 55',66'
extend towards one another at different angles of inclination. A
profile is brought about, which may be compared approximately to
that of FIGS. 1 and 2 in which context, as an alternative to FIGS.
3 and 4 a reversed arrangement of the crushing teeth 33',44'
is likewise conceivable.
Further momentary views, based on FIGS. 10 and 11 are shown in
FIGS. 12 14. The continuous modification of the successively forming
crushing chambers B2 B3 is shown, in which context in this case
as well identical components are denoted by identical reference
numerals.
In the examples cited in accordance with FIGS. 1 to 14 the crushing
rollers 12 are to be driven synchronously, in which case each crushing
roller 12 is provided with connected drive means, not shown in
detail, such as, for example, gear mechanisms, belts or the like.
FIG. 15 shows the developed view 1',2' of an arrow-shaped tooth
formation with an even number of annular gears and different pitches
or angles of inclination of the imaginary connection lines 55',66'
of the individual crushing teeth groups AB, CD. Except for the different
pitches of the lines 55',66' interconnecting the crushing teeth
33',44', this illustration corresponds approximately to that of
FIG. 2.
FIG. 16 shows the developed view 1',2' of an arrow-shaped tooth
arrangement with an even number of annular gears and even pitches
or angles of inclination of the imaginary connection lines 55',66'
and corresponds approximately to that according to FIG. 2.
FIG. 17 shows the developed view 1',2' of the crushing teeth 331441
arranged on a curve segment (imaginary connection line 55',66')
as an alternative to FIGS. 2415 and 16.
The person skilled in the art will select the type and arrangement
of the crushing teeth 33',44' on the crushing rollers 12 as a
function of the respective application.
FIGS. 18 and 19 are momentary views during an asynchronous operation
of the crushing rollers 12. In this example, the crushing rollers
12 dispose of independent drive means, such as gears, not shown
in detail. Setting of the differential velocity of the two crushing
rollers 12 may, for example, be regulated by a frequency converter.
The primary crushing chamber B2 can be seen. Further indicated is
in each case a secondary crushing chamber B4 developing in the
narrowing crushing gap of the counter-rotating crushing rollers
12 in the course of the further intake of the pre-crushed material.
As a result of the alternative arrangement according to the invention
of crushing teeth 33',44' in the selected configurations, the
following technical advantages are attained: Undelayed material
intake of relatively large material lumps is performed by the permanent,
continuous provision of one or more intake possibilities BI,B2B3
viewed over the entire length of the crushing rollers 12. Because
of the continuously closing, narrowing crushing chambers B1B2B3
the material, in the course of combing of the counter-rotating crushing
rollers 12 is stressed locally in respect of bending and shearing
as a result of the introduction of forces via the crushing teeth
33',44' and not compressively. A uniformly progressing comminution
is attained in the maximally three stress zones (primary, secondary,
and, where applicable, tertiary comminution), resulting in a division
of the crushing roller length into regions, in which, viewed in
the peripheral direction, the primary (B1 B3), secondary (B4) and,
optionally, tertiary comminution is performed. There are no dividing
lines between the transition points in this case. As the greatest
crushing forces occur during the primary size reduction, the installed
provision for torque for comminution may be lower, since there is
a concentration of forces onto few, operating tooth pairs 34;3',4'.
The stress on all machine elements, in particular the drive mechanism,
is lessened and with lower impact load. The overall stress dynamics
are rendered more even. As a result of the particular crushing roller
design and the additional comminution by utilizing a crushing comb
in conjunction with the stress on materials resulting therefrom,
the gap width being the defined smallest spacing of the roller surfaces
as well as of the tooth spacings to one another may be substantially
greater than in conventional roller crushers, in order to ensure
the desired end particle size. Material transport on the crushing
rollers, i.e. bringing about axial force components on the material,
in particular large material lumps, in order to avoid grooving and,
consequently, jamming of large material lumps. The material remains
in motion at all times until a suitable intake and roller position
comes about. Depending on the crushing chamber design B1B2B3
determined by the roller design including the tooth configuration
and number over the circumference, arrangement, rotor position or
use of a crusher beam, the particle size distribution of the final
particle may be set.
As a result of the tooth arrangement according to the invention,
contemplated in momentary views, a continuous formation of deep
three-dimensional, primary crushing chambers BI,B2B3 for the penetration
of large material lumps takes place. Because of the arrow-shaped
or arrow-like configuration in conjunction with--if required--a
synchronised crusher roller positioning in gripping position, the
simultaneous (or successive) formation of intake regions B1B2B3
on the roller surface is brought about. In particular, the efficiency
of the corresponding central tooth pair 77' of both crushing rollers
12 is improved, as oblong material lumps may come to lie in the
recess(es) BI,B2B3 deepening over the entire crushing roller length
towards the centre. The axial offset angle of the annular gears
1213 determines the pitch of the counter-oriented imaginary connection
lines 55',66' and is matched to the distribution on the periphery,
i.e. number of crushing teeth 33',44'. An arrangement is optimal,
which proceeds continuously, i.e. after passing through the first
arrow the central tooth pair 77' engages as start of the next following
arrow, in order to ensure a continuous crushing operation. The arrow
configuration, offset in opposite direction, described in FIGS.
10 and 11 differs from the arrow configurations discussed in FIGS.
1 to 4 in such a manner that the developing intake regions B2 B3
are not formed simultaneously during combing of the counter-rotating
crushing rollers 12 but successively, i.e. once the one roller
half has passed through the primary intake region B2 the primary
engagement of the other roller half takes place continuously. With
this design the object of a continuous comminution process/force
concentration may even be realised in the case of short roller lengths
having a low number of teeth in relation to the circumference. As
a result of the serial succession of effects, the pitch of the imaginary
connection lines 55',66' may be reduced by half, as compared to
the arrangement illustrated in FIGS. 1 to 4. This permits the provision
of larger intake chambers B2B3.
Both arrangements necessitate a distribution function to both sides
from the centre of the crushing chamber in order to exploit the
entire roller width by axial force components, especially in the
case of relatively large material lumps. The material is fed to
the multi-roller crusher, controlled normally via a feed conveyor,
in which context the feed direction may be transverse to the longitudinal
direction of the roller. The point of impact of the discharge parabola
may be set between the counter-rotating crushing rollers 12 as
target-oriented as possible. This arrangement avoids power- and
wear-intensive deflecting of the material flow, while, in particular,
the fines content in the feed material may be put through directly
and with the lowest resistance and dwell time possible, using as
large as possible a passage cross-section over the length of the
roller.
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