Note: Descriptions are shown in the official language in which they were submitted.
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A PITMAN OF A JAW CRUSHER, A JAW CRUSHER, A CRUSHING PLANT AND
A CRUSHING METHOD
FIELD OF THE INVENTION
The invention relates to a pitman of a jaw crusher, a jaw crusher and a
crushing
plant and a crushing method, which are suitable forcrushing mineral material.
BACKGROUND OF THE INVENTION
The function of the jaw crusher is based on the force pressing stone, the jaw
moving in respect of an eccentric shaft moves back and forth regarding the
fixed
jaw. Movable jaws i.e. pitmans of the jaw crushers have been produced in
various
different ways. A casted pitman is enclosed i.e. closed in its cross-sectional
profile.
In the patent publication EP1049539B1, there is presented a jaw crusher with a
pitman with closed cross-sectional profile.
Manufacturing a pitman according to a closed profile requires several
different
work phases. When casting, cores are needed for manufacturing closed profile
parts. The moving of cores during casting has lead to differences in wall
thicknesses of the webs, because of which the wall thickness of the castings
have
to be oversized, which adds to the cost and dynamic forces. It is difficult to
check
and correct casting and quality errors in an enclosed pitman. In an enclosed
structured pitman, various exhaust openings are needed for removing the sand
in
the core. Sand removal through exhaust openings after the casting is laborious
and time consuming.
In known solutions, for reaching sufficient strength plenty of material is
required in
the lower part of the pitman. This increases the mass of the pitman, which
increases dynamic forces.
When the material to be crushed is located one-sidedly in the crushing chamber
it
is a question of one-sided crushing. In that case, momentary transformations
are
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developed in the pitman due to the one-sided strain, which transformations
distort
the pitman. The transformations increase power requirement and reduce crushing
capacity. Additionally, the material in the pitman is exposed to fatigue,
especially in
the area of the supporting point of the toggle plate.
In some cases, the side plates of the body of the jaw crusher are joined with
each
other by an intermediate rod in the part between the ends of the body. A
typical
location for the intermediate rod is in the location of the pitman. A
horizontal hole
for the intermediate rod leading from the first side of the body to the second
side of
the body is formed in the pitman because of this. In the casting process, a
core is
placed in the hole for the intermediate rod, the sand of which core has to be
removed after casting. In cooling down, thermal stresses result in the hole
for the
intermediate rod that do not necessarily entirely disappear in the thermal
treatment.
It is known that the hole for the intermediate rod is non-machined and the
hole with
cast surface is sensitive to crack formation. The area of the hole for the
intermediate rod is a critical spot because of the peak stresses caused by the
crushing force.
SUMMARY
According to a first aspect of the invention, a pitman of a jaw crusher is
implemented, the pitman comprising an upper part, which comprises an upper
supporting point for supporting the pitman in a body of the jaw crusher, and a
lower
part, comprising a lower supporting point for supporting the pitman in the
body of
the jaw crusher through a toggle plate, wherein the lower part of the pitman
comprises sidewalls and a honeycomb structure open in a crushing direction,
the
honeycomb structure comprising one or more cross-sectional supports reaching
from a first sidewall of the pitman to a second sidewall of the pitman,
wherein the
upper part of the pitman comprises a backwards open cross-sectional profile
above
the honeycomb structure of the lower part.
Preferably, the lower supporting point of the pitman is arranged in the
location of
the cross-sectional support of the honeycomb structure. Preferably, the lower
supporting point of the pitman is arranged in the location of the cross-
sectional
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support of the honeycomb structure in the vertical direction of the pitman.
Preferably, the sidewalls of the pitman form the sidewalls of the honeycomb
structure; and the honeycomb structure comprises one or more vertical supports
intersecting with the cross-sectional supports/supports for dividing the space
between the sidewalls of the pitman vertically in parts.
Preferably, the honeycomb structure comprises a continuous back wall area to
which the sidewalls, vertical supports and cross-sectional supports are
attached
from their back part.
Preferably, the back wall area comprises a lower back wall area and an upper
back
wall area which join in the location of the cross-sectional support and the
back wall
areas are arranged parallel such that the force directed in the pitman by
means of a
toggle plate in a crushing event is substantially parallel with the direction
of the
back wall areas.
Preferably, the front surface of the lower part comprises front edges of the
sidewalls, vertical supports and cross-sectional supports for receiving a wear
part.
Preferably, a centering mechanism of the wear part is attached in the
intersections
of the vertical supports and cross-sectional supports in the front surface of
the
lower part.
According to a second aspect of the invention, a jaw crusher is implemented
for
crushing mineral material which jaw crusher comprises a pitman of a jaw
crusher
according to an embodiment of the invention.
According to a third aspect of the invention, a crushing plant is implemented
comprising a pitman of a jaw crusher according to an embodiment of the
invention
or a jaw crusher according to an embodiment of the invention.
According to a fourth aspect of the invention, a method is implemented for
increasing capacity of crushing mineral material in a jaw crusher or in a
crushing
plant, the jaw crusher or the crushing plant comprising a crushing chamber and
a
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pitman arranged in the crushing chamber, the pitman comprising an upper part
comprising an upper supporting point for supporting the pitman in a body of
the jaw
crusher, and a lower part comprising a lower supporting point for supporting
the
pitman in the body of the jaw crusher through a toggle plate, wherein in a
crushing
event, the pitman is moved, the lower part of which the pitman comprises
sidewalls
and a honeycomb structure open in a crushing direction, the honeycomb
structure
comprising one or more cross-sectional supports reaching from a first sidewall
of
the pitman to a second sidewall of the pitman, for dividing space between the
sidewalls horizontally in parts, wherein the upper part of the pitman
comprises a
backwards open cross-sectional profile above the honeycomb structure of the
lower
part.
Preferably, the toggle plate comprised by the jaw crusher is supported in the
lower
supporting point which is arranged in the location of the cross-sectional
support of
the honeycomb structure.
Preferably, the toggle force directed at the pitman through the toggle plate
is
conveyed into the crushing direction through the cross beam. Preferably, the
toggle
force directed at the pitman through the toggle plate is conveyed in the
crushing
process through the lower back wall area of the lower part.
According to a fifth aspect of the invention, there is implemented a method
according to which the lower part of the pitman of the jaw crusher is
manufactured
by casting without a core. Preferably, in the core-free manufacturing method
of the
pitman of the lower part, the hole for the intermediate rod is manufactured by
machining. Preferably, the hole for the intermediate rod is machined in a
discretionary location for controlling the strength and the residual tensions.
The
location of the hole for the intermediate rod may be chosen more freely than
in a
known hole manufacturing method by casting.
According to some embodiments, the upper part of the pitman comprises a
backwards open cross-sectional profile above the honeycomb structure of the
lower
part. Preferably, the backwards open cross-sectional profile comprises
vertical
webs between the sidewalls in addition to the sidewalls of the pitman.
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According to some embodiments, the upper part of the pitman comprises above
the honeycomb structure of the lower part a honeycomb structure like the
honeycomb structure of the lower part which is open from the front surface of
the
5 upper part of the pitman.
A cross-sectional support arranged in the honeycomb structure reduces or
removes bending of the pitman and the wear part compared with a known pitman,
which has poorer horizontal rigidity. The cross-sectional supports eliminate
bending and distortion horizontally. The cross-sectional support may reduce
support span which is in the pitman in the back of the wear part. The pressing
work in a crushing event is better focused in breaking the stone and not in
the
transformation (elasticity) of the pitman. Thus the stone may be crushed with
smaller stroke count and smaller stroke length. The capacity of the crusher
and
the crushing plant may be increased because the mineral material is crushed
and
does not stay waiting for a new stroke. Crushing work done by a smaller stroke
also affects other components of the crusher which may be lightened if needed.
If
needed, the mass of the flywheel and the counterweight of the crusher may be
reduced. The power source may be smaller in power, as well. The amount of the
energy engaged in the flywheel may be reduced. The environment is less
burdened because of savings in material and energy. If a known amount of
material is used the structure may be made more durable and more rigid.
The quality of manufacturing the pitman may be improved. There are less work
phases and the manufacturing may be speeded up. When casting no cores (web)
are needed which cause differences in wall thickness and additional costs. In
manufacturing the pitman less material is needed which reduces the mass of the
pitman. Weight may also be reduced by machining the edges of the webs because
the machining surface has significantly higher fatigue strength than the
casting
surface. The casting is more easily done. In the manufacturing, a considerably
better end quality may be achieved and the wall thicknesses are easily checked
and the weight of the pitman optimized. The openness makes it easy to check
and
fix casting defects. Casting defects may be removed by grinding from the web
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edges which are critical in tension. Sand cleaning holes are not needed and
the
sand removal phase is left out.
Holes formed in the structure because of casting may be avoided by an open
structure of the pitman. Thus strength-weakening stress peaks caused by
crushing
forces may be diminished in the structure. The hole for the intermediate rod
may
be made entirely by machining, in which case the fatigue strength of the
structure
is better than in case of the non-machined surface generated after casting. In
that
case one may get rid of the residual tensions of the hole, as well.
Additionally, the
location of the hole for the intermediate rod may be better chosen when in a
whole
less residual tension remains in the pitman than in the known pitman.
In the solution of the pitman, strength advantage is achieved when the force
of the
toggle plate is received on a nearly parallel plate flange (lower and upper
back wall
area) which continues above the joint point to a sufficient distance for
minimizing
bending and pulling tensions. The pitman may be made lighter as the known
pitman by a honeycomb structure continuing above the joint point of the toggle
plate. According to some embodiments, the openness of the cross-sectional
profile
of the pitman is changed in a strength-wise sufficient distance from the joint
point
between the toggle plate and the pitman. The desired loading level of the
crusher/pitman and the life span as well as the fixing points of the wear
parts
define the dimensions of the pitman which further define the size of the
distance.
In some embodiments, the fixing point is taken from such a distance from the
joint
point in which point the height of the web is 80-90% of the maximum height of
the
web. The height of the web is measured as a perpendicular distance from the
front
surface of the lower part of the pitman to the outer curve of the web.
Additionally,
the lower part of the pitman is a firm honeycomb structure, to the connection
areas
of which strength-increasing roundings are made.
Various embodiments of the present invention are or have been illustrated with
reference to one or some aspects of the invention. It is clear to person
skilled in
the art that any embodiment of an aspect of the invention may be applied in
the
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same aspect and other aspects either by itself or in connection with various
other
embodiments.
SHORT DESCRIPTION OF THE DRAWINGS
The invention will be described, by way of example only, with reference to the
accompanying schematic drawings, in which:
Fig. 1 presents from side a crushing plant suitable for crushing mineral
material;
Figs. 2 and 3 present a first pitman of a jaw crusher, the cross-sectional
profile of
which is open backwards in the upper part of the pitman and, in the support
area
of the toggle plate, the pitman comprises a forwards open honeycomb structure;
Fig. 4 presents a cross section of the pitman presented in figs. 2 and 3; and
Figs. 5 and 6 present a second pitman of a jaw crusher, the cross-sectional
profile
of which is open forwards in the upper part of the pitman and in the area of
the
supporting point of the toggle plate, the pitman comprises a forwards open
honeycomb structure.
DETAILED DESCRIPTION
In the following description like reference signs denote like parts. It should
be
realized that the presented figures are not in scale as a whole, and they
serve
merely to illustrate the embodiments of the invention.
In Fig. 1, there is presented a processing apparatus of mineral material, a
crushing
plant 200 comprising a jaw crusher 100. In the crushing plant 200, there is a
feeder 103 for feeding material into the jaw crusher 100 and a belt conveyor
106
for transferring crushed material further from the crushing plant.
The belt conveyor 106 presented in fig. 1 comprises a belt 107 arranged to
proceed around at least one drum 108. The crushing plant 200 also comprises a
power source and a control centre 105. The power source may be for instance a
diesel or electric motor, which provides energy to be used by process units
and
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hydraulic circuits.
The feeder 103, the crusher 100, the power source 105 and the conveyor 106 are
attached to the body 101 of the crushing plant, which in this embodiment also
comprises a track platform 102 for moving the crushing plant 200. The crushing
plant may also be totally or partly wheel-based or movable by legs.
Alternatively, it
may be movable/towable for instance with help of a truck or some other
exterior
power source.
Mineral material may be for instance quarried stone or it may be asphalt or
decommissioning waste such as concrete, or brick etc. In addition to the
foregoing,
the crushing plant may be a fixed crushing plant.
The embodiments of the pitman 1, 1' of the jaw crusher 100, presented with
help
of figs. 2-6, may be used for instance in the crushing station 200 in fig. 1.
The
crushing station 200 and the jaw crusher 100 are configured to receive the
pitman
1, 1', which can be lighter than the known pitmans, when an increase in
strength
caused by the stiffening of the pitman structure is taken into account. The
power
used by the crusher per the amount of crushed mineral material may be smaller
than with known applications because in the crushing event, less energy is
used in
the transformation of the pitman. On the other hand, a greater crushing volume
may be achieved with the same crushing power because a greater part of drive
power may be focused in crushing mineral material.
In figs. 2, 3 and 4, there is presented a pitman 1 open in two directions,
which is
preferably manufactured by casting. The upper part 2 of the pitman comprises
an
upper supporting point 3 for supporting the pitman in the body of the jaw
crusher
through an eccentric shaft (not presented in figs.). The first supporting
point 3
defines a hole which reaches from the side of the pitman to the other. The
lower
part 4 of the pitman comprises a lower supporting point 5 for supporting the
pitman
in the body of the jaw crusher through a toggle plate (not presented in
figs.). There
is arranged a supporting groove 6 in the lower supporting point 5. The force
and
direction of the toggle plate are presented in fig. 4 by an arrow 30.
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In an example, the wear part which is aimed to be fixed in front of the pitman
is
two-part (not presented in figs.) but one-part and multi-part wear parts may
be
used, as well. The upper wear part is fixed in the front surface 8 of the
front wall 7
of the upper part of the pitman and the lower wear part is fixed in the front
surface
9 of the lower part of the pitman below the upper wear part. The pitman 1
comprises first fixing means 10 in the upper part of the front surface 8 of
the upper
part for fixing wear parts, second fixing means 11 between the front surfaces
of
the upper and lower part and third fixing means 12 below the front surface of
the
lower part. Holes, among others, are arranged as fixing means for fixing
wedges.
The support of the wearing plate to be fixed in the side of the crushing
chamber in
the pitman may be improved by the new structure of the pitman. A cross-
sectional
support 15 may be formed in the pitman in cross direction of the pitman (in
the
width direction of the crushing chamber), which is preferably horizontal, when
areas supporting the wearing plate from back in cross direction may be formed
in
the pitman in addition to the vertical supports.
In figs. 2, 3 and 4, the cross-sectional profile of the pitman is open
backwards in
the upper part of the pitman and open forwards in the area of the supporting
point
5 of the toggle plate. In the area of the supporting point 5 of the toggle
plate, the
lower part of the pitman comprises a honeycomb structure open forwards. The
honeycomb structure vertically comprises sidewalls 13 and vertical supports 14
of
the pitman, which vertically divide the space between the sidewalls in parts.
The
honeycomb structure additionally comprises one or more cross-sectional
supports
15, which intersect with the vertical support/supports 14 and horizontally
divide the
profile of the lower part 4 in parts, which profile is open forwards (open in
the
crushing direction). There may be one or more vertical supports, in the
examples
in figures there are two vertical supports. The cross-sectional support 15
improves
the sideward rigidity of the vertical supports when the support span of the
supports
diminishes. In the examples of the figures, the honeycomb structure comprises
six
compartments divided by two vertical supports and one cross-sectional support
in
the middle. A centering mechanism 16 of the wear part, such as a wedge, is
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attached in the intersections of the vertical supports and cross-sectional
supports
in the front surface 9 of the lower part 4.
In crushing, the sideward forces coming across to the pitman 1 from the wear
part
5 and the forces distorting the pitman are received in the object rigidity-
wise better
than the known one, the wear part stays better in position sideward and the
transformation caused by the crushing process in the whole pitman and the
vertical supports may be reduced. Thus the crushing energy is better focused
in
the crushing mineral material and the life span of the pitman increases.
Preferably, the sidewall 13, the vertical support 14 and the cross-sectional
support
are ribs or walls commencing forward from the back wall areas 17 and 18
connecting the sidewalls 13 of the lower part of the pitman. The lower back
wall
area 17 is arranged behind the lower compartments of the honeycomb structure.
15 The upper back wall area 18 is arranged behind the upper compartments of
the
honeycomb structure. The lower back wall area 17 continues uniformly onto the
upper back wall area 18 in the area of the supporting point 5 of the toggle
plate (in
the area of the second supporting point of the jaw crusher). Preferably, both
back
wall areas 17, 18 are arranged parallel with the direction of the toggle
plate. In that
case, there are forces formed in the direction of the back walls in the back
walls
17, 18, which has been illustrated with help of the arrows drawn in the cross-
section of fig. 4. In the presented structure, the back wall areas 17, 18 have
been
designed to receive compression and/or pulling and not bending. This increases
the life span of the pitman and the wall thickness of the pitman may be
reduced in
the lower part.
Preferably, the foremost point of the sidewalls, vertical supports and
horizontal
supports forms a part of the front surface 9 of the lower part of the pitman
for
supporting the back surface of the wear part.
The pitman 1 may comprise a hole 19 for the intermediate rod in the upper part
2
but it is not necessary. Fig. 3 presents the pitman 1 from back, the upper
part of
which pitman comprises a backwards open structure where the area between the
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sidewalls 13 is divided in vertical compartments by vertical webs 20 fixed in
the
front wall 7. The vertical webs 20 are connected with each other with
horizontal
supports 21, the web height of which from the front wall is only a part of the
height
of the sidewalls and vertical webs.
In fig. 4, the crushing power directed at the pitman is illustrated with the
arrow F.
The uniform back wall area 17, 18 and the cross-sectional support 15 transfer
the
crushing force as steadily as possible to the toggle plate, which in a normal
crushing event receives the most of the crushing force (does not receive
everything because a part of it is divided to the bearing of the upper end).
The
lower back wall area 17 is a particularly important wall because when crushing
fine
material the crushing force increases considerably below. A typical angle for
the
direction 30 of the toggle plate is approximately 45 degrees regarding the
front
surface 9 of the pitman, and the range on various settings and in various
movement positions (min-max) of the pitman is approximately 5-10 degrees.
The openness of the cross-sectional profile of the pitman 1 is changed in a
strength-wise sufficient distance (circle and reference number 31) from the
joint
point (arrow and reference number 30) between the toggle plate and the pitman.
The desired loading level and the life span as well as the fixing points of
the wear
parts define the dimensions of the pitman, which further define the size of
the
distance. In an embodiment, the fixing point is taken from such a distance
from the
joint point in which point the height h of the web 13, 20 is 80-90% of the
maximum
height H of the web 13, 20. The height of the web 13, 20 is measured as a
perpendicular distance from the front surface 9 of the lower part of the
pitman to
the outer curve of the web 13, 20.
In the open profile of the pitman 1, the critical points of tensions are
located in the
free edges 31, 31' of the webs (walls 13) of the pitman. Because the lower
free
edge 31 is located within such a distance from the joint point where the
height of
the web is as great as possible, the tensions directed to the edge 31 may be
achieved smaller.
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The honeycomb structure reduces the support spans of the jaws (wear parts) and
reduces vertical and cross-sectional bending transformations of the pitman and
thus supports the wear parts even more than before. Because the energy being
used is not spent in the bending transformations but in the crushing event
itself the
efficiency of crushing is improved.
Figs 5 and 6 present a second pitman 1' of a jaw crusher, the cross-sectional
profile of which is open forwards in the upper part 2 of the pitman. In the
area of
the supporting point 5 of the toggle plate, the pitman 1' comprises a
honeycomb
structure open in the direction of the crushing chamber, which structure is
presented in connection with figs. 2-4. The second pitman 1' is thus a pitman
open
in one direction. In the second pitman 1', the upper supporting point 3 of the
upper
part 2, the lower part 4, the honeycomb structure of the lower part, the lower
supporting point 5 and the hole 19 for the intermediate rod are similar with
the first
pitman 1. The second pitman need not necessarily have the hole for the
intermediate rod.
In figs. 5 and 6, the upper part 2 of the pitman 1' comprises a honeycomb
structure
like the honeycomb structure of the lower part 4, which structure is open on
the
front surface 8' of the upper part of the pitman. The honeycomb structure
vertically
comprises the sidewalls 13 and vertical supports 14' of the pitman, which
vertically
divide the space between the sidewalls in parts. The honeycomb structure
additionally comprises one or more cross-sectional supports 15', which
intersect
with the vertical support/supports 14' and horizontally divide the profile of
the
upper part 2, which profile is open forwards (open in the crushing direction).
There
may be one or more vertical supports, in the examples in figures there are two
vertical supports. The cross-sectional support 15' improves the sideward
rigidity of
the vertical supports. In the examples of the figures, the honeycomb structure
comprises six compartments which are divided by two vertical supports and one
cross-sectional support in the middle. A centering mechanism 16' of the wear
part,
for example a wedge, is attached in the intersections of the vertical supports
and
cross-sectional supports. In the upper part, the sidewall 13, the vertical
supports
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14' and the cross-sectional support 15' are ribs or walls commencing forward
from
the back wall 17' of the upper part of the pitman.
The pitman 1, 1' may be manufactured, instead of casting or additionally, by
welding or by a corresponding method, where an object is attached to another
object by using at least partial melting of the material of the object, using
additive
or without additive.
The foregoing description has provided non-limiting examples of some
embodiments of the invention. It is however clear to a person skilled in the
art that
the invention is not restricted to details of the embodiments presented above,
but
that it can be implemented using equivalent means.
Furthermore, some of the features of the above-disclosed embodiments may be
used to advantage without the corresponding use of other features. As such,
the
foregoing description shall be considered as merely illustrative of the
principles of
the present invention, and not in limitation thereof. Hence, the scope of the
invention is only restricted by the appended patent claims.
