Abstrict A cone crusher includes a frame, a shaft supported by the frame,
and a head disposed on the shaft. An eccentric mechanism is coupled
to the head. A one-way clutch is coupled to the shaft, and a friction
torque limiting clutch is disposed within the head and coupled between
the head and the one-way clutch.
Claims What is claimed is:
1. A cone crusher, comprising: a frame; a shaft supported by the
frame; a head disposed on the shaft; an eccentric mechanism coupled
to the head; a one-way clutch coupled to the shaft; and a friction
torque limiting clutch disposed within the head and coupled between
the head and the one-way clutch.
2. The cone crusher of claim 1 further comprising a set of universal
joints coupled between the one-way clutch and the friction torque
limiting clutch.
3. The cone crusher of claim 2 wherein the set of universal joints
includes two universal joints.
4. The cone crusher of claim 3 wherein the one-way clutch is a
backstop clutch.
5. The cone crusher of claim 2 wherein the one-way clutch is coupled
to a spindle extending from the shaft, whereby the one-way clutch
is radially constrained with respect to a longitudinal axis of the
shaft.
6. The cone crusher of claim 2 wherein the friction torque limiting
clutch comprises: a housing; a plurality of separators secured to
the housing; a plurality of friction plates disposed adjacent the
separators; and a number of springs compressing the separators and
the friction plates.
7. The cone crusher of claim 6 wherein the friction torque limiting
clutch has a torque set point, above which the friction plates and
the separators travel with respect to one another.
8. The cone crusher of claim 7 wherein the friction between the
friction plates and the separators continuously retards travel with
respect to one another.
9. An anti-spin mechanism in combination with a rock crusher having
a head, an eccentric, and a shaft, comprising: a one-way clutch
coupled to the shaft, the one-way clutch permitting rotation of
the head in a first direction, and inhibiting rotation of the head
in a second direction; and a friction torque limiting clutch disposed
within the head and coupled to the one-way clutch, wherein the friction
torque limiting clutch protects the one-way clutch by permitting
rotation of the head in the second direction in the case of an excessive
torque loading.
10. The anti-spin mechanism of claim 9 further comprising a set
of universal joints coupled between the one-way clutch and the friction
torque limiting clutch.
11. The anti-spin mechanism of claim 10 wherein the one-way clutch
is a backstop clutch.
12. The anti-spin mechanism of claim 10 wherein the one-way clutch
is coupled to a spindle extending from the shaft, whereby the one-way
clutch is radially fixed with respect to the shaft.
13. The anti-spin mechanism of claim 9 wherein the friction torque
limiting clutch comprises: a housing; a plurality of separators
secured to the housing; a plurality of friction plates disposed
adjacent to the separators; and a number of springs compressing
the separators and the friction plates.
14. The anti-spin mechanism of claim 13 wherein the friction torque
limiting clutch has a torque set point, above which the friction
plates and the separators slip with respect to one another.
15. The anti-spin mechanism of claim 14 wherein the friction torque
limiting clutch continuously brakes the head as long as the head
travels in the second direction.
16. A rock crusher, comprising: a stationary shaft; a head coupled
to the shaft, the head driven in a gyratory manner by an eccentric;
a lower spindle extending from the shaft; a backstop clutch coupled
to the lower spindle; an upper spindle coupled to the backstop clutch;
and a friction torque limiting clutch coupled between the upper
spindle and the head.
17. The rock crusher of claim 16 further comprising a set of universal
joints coupled between the backstop clutch and the friction torque
limiting clutch.
18. The rock crusher of claim 17 wherein the friction torque limiting
clutch comprises: a housing; a plurality of separators secured to
the housing; a plurality of friction plates disposed adjacent the
separators; and a number of springs compressing the separators and
the friction plates.
19. The rock crusher of claim 18 wherein the friction torque limiting
clutch has a torque set point, above which the friction plates and
the separators slip with respect to one another.
20. The rock crusher of claim 16 wherein the rock crusher is a
cone crusher.
21. A rock crusher, comprising: ahead; a stationary shaft; means
coupled between the head and the shaft for permitting rotation of
the head in only one direction; and means for limiting the torque
on the means for permitting rotation of the head in only one direction,
the means for limiting the torque comprising a number of plates
that frictionally engage one another.
22. The rock crusher of claim 21 wherein the means for permitting
rotation of the head in only one direction is a backstop clutch.
23. The rock crusher of claim 21 wherein the means for limiting
the torque is a friction torque limiting clutch.
Description FIELD OF THE INVENTION
The present invention generally relates to rock crushers. More
specifically, the present invention relates to an anti-spin mechanism
having a torque limiter for use on a conical rock crusher.
BACKGROUND OF THE INVENTION
Rock crushers, such as cone crushers, generally include an eccentric
assembly that rotates about a main shaft and imparts gyratory motion
to a head assembly. Material to be crushed is loaded into a feed
hopper that feeds into a bowl assembly. The material, generally
rock, is crushed between a bowl liner disposed in the bowl assembly
and a mantle on the crusher head assembly.
To crush rock between the head assembly and the bowl assembly,
gyratory motion is imparted to the head assembly to alternately
widen and narrow the gap between the head assembly and bowl assembly.
The gyratory motion may be imparted via an eccentric that rotates
with respect to a stationary shaft and directly imparts the eccentric
motion to the head assembly. Alternatively, an eccentric assembly
may be used to impart gyratory motion to a movable shaft, which
in turn imparts gyratory motion to the head assembly. In either
case, a frame supports the shaft and head assembly, and a countershaft
or other driving mechanism is utilized to drive the eccentric assembly.
The eccentric generally rotates at a high rate of speed (e.g.,
200 rpm). Although the interface between the eccentric and the head
is lubricated and generally includes a bushing disposed between
the two components, without counteracting forces preventing the
movement, the head tends to rotate along with the eccentric.
When the crusher is operating and crushing rock (at-load), the
head rotates slowly in a direction opposite to the eccentric direction
of rotation due to the countervailing forces of the material being
crushed. However, during no-load operation (eccentric rotating but
no rock being crushed), the head tends to rotate in the direction
of the eccentric. Such rotation is not desirable because rock can
degrade the crushing surface of the head as the head transitions
from rotating in the direction of the eccentric during no-load operation
to the opposite rotation of normal crushing operation. Further,
improper introduction of rock into a machine can cause ejection
of the rock from the machine when the head is rotating at a high
rate of speed.
Certain rock crushers include an anti-spin mechanism to prevent
undesirable rotation during no-load conditions. The anti-spin mechanism
may be a one-way clutch, such as a backstop clutch, that prevents
rotation of the head in the direction of eccentric travel but permits
travel of the head in the opposite direction during normal crusher
operation.
During certain operational circumstances, a large torque driving
the head in the direction of eccentric travel may be encountered.
For example, a head bushing may fail, thus causing substantial friction
between the head and eccentric, forcing the head to travel in the
direction of the eccentric. Further, during no-load operation, a
rock may fall between the head and bowl and impart a crushing force
on the head that has a component in the direction of eccentric travel.
Moreover, during at-load crushing operations, certain rock configurations
may be encountered that result in a large torque on the head being
generated in the direction of the eccentric. In all of these circumstances,
a backstop clutch may be at risk for rupture, as the backstop clutch
is designed to prevent the head from rotating in the direction of
the eccentric during no-load operation, but is not designed to withstand
excessive reverse torque loads. Even if the backstop clutch does
not fail, other crusher components are at risk for damage due to
the unusual torque load.
There is no backstop clutch design for use in rock crushers that
has free motion in one rotational direction and a friction clutch
torque limit to prevent excess torque in the locked direction. Even
if a backstop clutch were designed to incorporate such functionality,
the head would have to be removed to service the device. Replacing
the backstop clutch with a friction plate torque limiting clutch
would be disadvantageous because of the continuous rotation present
during at-load operation. The continuous rotation would cause excessive
wear on the clutch, resulting in an unacceptably short component
service life.
Secondary mechanisms such as shear pins can be utilized to protect
the one-way backstop clutch. However, the available space within
the head assembly of a conventional rock crusher is limited, presenting
design challenges for the device utilized to protect the one-way
clutch.
Certain conventional crusher designs utilize shear pins or bolts
to protect the backstop clutch. The shear pins permit rotation of
the head in the direction of the eccentric by shearing off in response
to unusually large torque events in the direction of the eccentric,
thus protecting the backstop clutch and other crusher components.
However, the utilization of shear pins to protect the one-way clutch
presents operational difficulties, as failed shear pins must be
replaced after each occurrence of an excessive reverse torque loading.
The increased crusher inoperability adds to the overall operation
and maintenance costs of a crusher installation.
Another method of protecting the one-way clutch utilizes a torque
limiter coupled to the clutch. U.S. Pat. No. 4666092 to Bremer,
issued May 18 1987 discloses such a device. The Bremer device
utilizes a resetting torque limiter that permits rotation of the
crusher head in the direction of the eccentric in the case of excessive
torque on the clutch. Thus, the Bremer design eliminates the necessity
of shear pins.
During normal operation, the Bremer torque limiter prevents rotation
of the crushing head relative to the one-way clutch by utilizing
a number of balls forced into corresponding detents by compression
springs. Upon an overload exceeding the torque limit of the torque
limiter, the balls are forced out of the detents and the torque
limiter permits rotation of the head relative to the one-way clutch
until the balls are reset into the detents.
A disadvantage of the Bremer device is that the balls may snap
into and out of the detents several times before the torque limiter
resets, causing multiple shocks to the crusher drive train before
the balls properly reset and prevent rotation of the head relative
to the one-way clutch. Further, the Bremer device does not continuously
dissipate energy to slow down head travel in the direction of the
eccentric in the case of unusual torque loadings, as the torque
limiter is not a friction clutch device. Accordingly, once the Bremer
device begins to rotate, the crushing head may not stop spinning
until the crusher is placed at load for a period of time to allow
the device to reset. A further disadvantage of the Bremer device
is that both the one-way clutch and torque limiter are coupled to
the head, such that both devices gyrate along with the head, which
can prevent proper engagement of the springs in the one-way clutch.
U.S. Pat. No. 4206881 to Werginz, issued Jun. 10 1980 utilizes
a hydraulic motor as an anti-spin mechanism. The hydraulic system
does not require shear pins or a torque limiter. Instead, the hydraulic
motor is designed to rotate in the direction of the eccentric in
the case of a reverse torque overload. However, the hydraulic system
requires additional hydraulic components, adding size, expense and
complexity to the anti-spin mechanism.
Accordingly, there is a need for a rock crusher that includes an
anti-spin mechanism that does not utilize shear pins to protect
a one-way clutch. Further, there is a need for an anti-spin mechanism
that does not utilize a hydraulic motor or pump. Further still,
there is a need for an anti-spin mechanism that permits the one-way
clutch to remain stationary during normal crusher operation, rather
than gyrating along with the crusher head. Further still, there
is a need for an anti-spin mechanism that includes a torque limiting
mechanism that both protects the one-way clutch and fits into the
small space allowed within the crusher head assembly. Yet further
still, there is a need for a device to protect a one-way clutch
that provides continuous braking once an excessive reverse torque
loading passes, to dissipate the energy of the rotating head and
bring the head to a stop.
It would be desirable to provide a system and/or method that provides
one or more of these or other advantageous features. Other features
and advantages will be made apparent from the present specification.
The teachings disclosed extend to those embodiments that fall within
the scope of the appended claims, regardless of whether they accomplish
one or more of the aforementioned needs.
SUMMARY OF THE INVENTION
One embodiment relates to a cone crusher. The cone crusher includes
a frame, a shaft supported by the frame, and a head disposed on
the shaft. An eccentric mechanism is coupled to the head and a one-way
clutch is coupled to the shaft. A friction torque limiting clutch
is disposed within the head and is coupled between the head and
the one-way clutch.
Another embodiment relates to an anti-spin mechanism for a rock
crusher having a head, an eccentric, and a shaft. The anti-spin
mechanism includes a one-way clutch coupled to the shaft. The one-way
clutch permits rotation of the head in a first direction and inhibits
rotation of the head in a second direction. A friction torque limiting
clutch is disposed within the head and is coupled to the one-way
clutch. The friction torque limiting clutch protects the one-way
clutch by permitting rotation of the head in the second direction
in the case of an excessive torque load.
A further embodiment relates to a rock crusher having a stationary
shaft and a head coupled to the shaft. The head is driven in a gyratory
manner by an eccentric. A lower spindle extends from the shaft,
and a backstop clutch is coupled to the lower spindle. An upper
spindle is coupled to the backstop clutch, and a friction torque
limiting clutch is coupled between the upper spindle and the head.
A still further embodiment relates to a rock crusher having a head
and a stationary shaft. The rock crusher includes means coupled
between the head and the shaft for permitting rotation of the head
in only one direction. The rock crusher further includes means for
limiting the torque on the means for permitting rotation of the
head in only one direction. The means for limiting the torque includes
a number of plates that frictionally engage one another.
A still further embodiment relates to a method of performing maintenance
on a rock crusher having a one-way clutch coupled to a torque limiter
disposed within a head assembly beneath a feed plate and a top plate.
The top plate is fastened to the head assembly and the torque limiter.
The method includes the steps of removing the feed plate, unfastening
the top plate from the head assembly, and lifting the torque limiter
out of the head assembly.
Alternative embodiments of the invention relate to other features
and combinations of features as may be generally recited in the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will become more fully understood from the following
detailed description, taken in conjunction with the accompanying
drawings, wherein like reference numerals refer to like elements,
in which:
FIG. 1 is a cross sectional view of a rock crusher;
FIG. 2 is a more detailed sectional view of the rock crusher illustrated
in FIG. 1 with partial cut-away views detailing portions of an anti-spin
mechanism; and
FIG. 3 is a more detailed cut-away front view of a friction torque
limiting clutch for use in the anti-spin mechanism illustrated in
FIG. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1 a crusher 10 includes a main frame 12 that
supports the components of the crusher 10 including a main shaft
14. FIG. 1 shows a standard size of the crusher 10 on the left,
and a short head size on the right. In the embodiment depicted in
FIG. 1 the main shaft 14 is stationary and an eccentric 16 is rotatably
disposed about the main shaft 14. The eccentric 16 rotates with
an eccentric bushing 18 about main shaft 14.
Crusher 10 can be embodied as a conical crusher manufactured by
Metso Minerals (Milwaukee) Inc., such as an MP.TM. Series cone crusher
modified to include an advantageous anti-spin mechanism 50 (FIG.
2). The type of rock crusher and its various components are not
described in limiting fashion. The principles of anti-spin mechanism
50 can be applied to any crusher apparatus in which an anti-spin
mechanism is desirable.
A gear 22 is fixed to the eccentric 16 and is driven by a countershaft
24 having a pinion 26 engaged with gear 22. The countershaft 24
may be driven by any suitable motor force.
A head 30 is disposed above main shaft 14 and includes a head ball
32 that is axially supported in a socket 34 and socket liner 36
disposed on main shaft 14. A head bushing 20 is rotatably coupled
to eccentric 16 and transmits motion from eccentric 16 to head 30.
Head 30 includes a mantle 28 that serves as a crushing surface.
A bowl 42 supported by main frame 12 includes a bowl liner 44 that
serves as a crushing surface opposite mantle 28. An adjustment ring
46 permits vertical adjustment of bowl 42 to change the gap between
bowl liner 44 and mantle 28 thus changing the crusher 10 setting.
A feed hopper 48 serves as a receptacle for the input of rock to
be crushed, and feeds the rock into the gap between mantle 28 and
bowl liner 44.
In operation, countershaft 24 drives eccentric 16 to impart gyratory
motion to head 30. Material to be crushed is fed into feed hopper
48 is crushed between mantle 28 and bowl liner 44 and exits out
of crusher 10.
Referring to FIG. 2 anti-spin mechanism 50 is disposed within
head 30. A lower spindle 52 extends upwardly from main shaft 14
and is disposed within a one-way clutch, shown as, but not limited
to backstop clutch 54. Backstop clutch 54 may utilize any of a number
of conventional methods of permitting rotation in one direction
but not in the opposite direction. A set of universal joints, lower
U-joint 56 and upper U-joint 58 are coupled between backstop clutch
54 and an upper spindle 60. Upper spindle 60 is disposed within
a torque limiting clutch, shown as friction torque limiting clutch
62.
Further referring to FIG. 2 a top plate 38 is bolted to friction
torque limiting clutch 62 and to head 30. A feed plate 40 is disposed
over the top plate 38.
In an exemplary embodiment, during at-load crusher 10 operation,
backstop clutch 54 remains radially constrained with respect to
the longitudinal axis of lower spindle 52. Backstop clutch 54 permits
normal rotation of head 30 in a direction opposite to the rotational
direction of eccentric 16. The universal joints, lower U-joint 56
and upper U-joint 58 accommodate head 30 motion so that only torque
is transmitted between backstop clutch 54 and friction torque limiting
clutch 62.
Referring to FIG. 3 friction torque limiting clutch 62 includes
a number of springs 64 that compress a series of friction plates
66 and separators 68. The friction torque limiting clutch 62 may
be set at differing torque set points to permit rotation of upper
spindle 60 relative to a housing 70 in the case of a torque overload.
As long as the torque exceeds the set point, friction plates 66
will slip relative to separators 68 while continuing to transmit
torque equal to the torque set point. Upper spindle 60 includes
splines 72 that are keyed to friction plates 66 but not to separators
68 which are fixed to housing 70.
Referring again to FIGS. 1 and 2 during normal at-load crusher
10 operation, head 30 slowly rotates in a direction opposite that
of eccentric 16. During no-load operation, wherein head 30 would
rotate in the direction of eccentric 16 were it not prevented from
doing so, backstop clutch 54 prevents such head rotation. Friction
torque limiting clutch 62 is set such that head 30 does not rotate
in the direction of eccentric 16 during normal no-load operation,
as the friction set point between friction plates 66 and separators
68 is not overcome by the torque generated by the friction between
eccentric 16 and head 30 via head bushing 20. During both at-load
and no-load operation, upper spindle 60 does not rotate with respect
to housing 70 of friction torque limiting clutch 62.
During certain circumstances, an unusual reverse torque loading
will be encountered, whereby head 30 is driven in the direction
of the eccentric 16 by a greater than normal force. Such an excessive
reverse torque load may be due to a head bushing 20 failure, an
unusual rock loading during the transition from no-load to at-load
operation, or by a large rock that imparts a torque in the direction
of the eccentric 16 during at-load operation. The backstop clutch
54 will not permit rotation of head 30 in the direction of eccentric
16 but if the excessive reverse torque loading exceeds the set
point of friction torque limiting clutch 62 housing 70 will rotate
with respect to upper spindle 60 permitting movement of head 30
in the direction of eccentric 16 thus preventing the, possible
rupture of backstop clutch 54 or damage to other crusher 10 components.
In one embodiment, the set point of the friction torque limiting
clutch for a Metso Minerals MP800 crusher is 10170 N-m or 7500
ft-lbs.
As long as the excessive reverse torque loading exceeds the set
point of friction torque limiting clutch 62 head 30 is permitted
to rotate in the direction of eccentric 16. Once the excessive reverse
torque loading has ceased, the friction between friction plates
66 and separators 68 slows the motion of head 30 until the differential
rotation between housing 70 and upper spindle 60 ceases. Accordingly,
at no time is the head 30 permitted to "freewheel" along
with eccentric 16 as is the case for conventional crusher designs
utilizing a non friction-based torque limiter.
Friction torque limiting clutch 62 may be procured from any number
of industry suppliers. One such supplier of torque limiting clutches
is Power Transmission Technology, Inc., of Sharon Center, Ohio.
In particular, the friction torque limiting clutch 62 may be a Power
Transmission Technology CMD Series compact multiple disk friction
torque limiter, such as model CMD 162-12-103 which includes bushings
that limit the radial motion of upper spindle 60 within friction
torque limiting clutch 62 during crusher 10 operation.
Because the set of universal joints 56 58 is disposed between
backstop clutch 54 and friction torque limiting clutch 62 backstop
clutch 54 may be disposed directly on stationary main shaft 14
thus eliminating the difficulties associated with subjecting backstop
clutch 54 to gyrating motion.
In an exemplary embodiment, universal joints 56 and 58 may be procured
from a supplier of power transmission components, such as from Johnson
Power Ltd. of Broadview, Ill. In particular, the universal joints
may be Series FL90W universal joints.
Friction torque limiting clutch 62 has a compact design permitting
placement of friction torque limiting clutch 62 within head 30 as
depicted in FIGS. 1 and 2. Further, expenses are saved through the
utilization of a friction-based clutch system rather than a hydraulic
system that would necessitate further hydraulic support components.
A further advantage of the friction torque limiting clutch 62 relates
to the calibration of the crusher 10 setting. An automation package
may be used to calibrate the crusher 10 setting. The crusher 10
setting is calibrated by rotating the bowl 42 to reduce the gap
between the mantle 28 and the bowl liner 44 to zero when the crusher
10 is at rest. Crusher designs that include shear pins as a torque
limiting mechanism are not suited for such automated calibration,
as the torque generated by the contact of the bowl liner 44 against
the mantle 28 rotates the head 30 in the direction of the eccentric
16 thus resulting in failed shear pins. The present invention permits
automated calibration because the friction torque limiting clutch
62 permits rotation of the head 30 with the bowl 42 once the mantle
28 and bowl liner 44 contact one another. Thus, anti-spin capability
is successfully combined with automatic crusher 10 setting calibration.
In an exemplary embodiment, anti-spin mechanism 50 is utilized
on an MP.TM. Series crusher manufactured by Metso Minerals (Milwaukee)
Inc. Anti-spin mechanism 50 is not limited to use with such crushers,
however, and may be utilized with respect to other rock crushers
that have a need for an anti-spin mechanism 50.
Preferably, friction torque limiting clutch 62 may be serviced
without removing head 30 from crusher 10. Referring to FIG. 2 one
method for performing such "top surface" involves first
removing the feed plate 40 which may be bolted in place. Next,
the top plate 38 is unfastened from head 30. Once top plate 38 has
been unfastened from head 30 the top plate 38 along with friction
torque limiting clutch 62 may be removed from within head 30 by
sliding top plate 38 and friction torque limiting clutch 62 off
upper spindle 60. Alternatively, top plate 38 may first be unbolted
from friction torque limiting clutch 62 and removed from head 30
before accessing and/or removing friction torque limiting clutch
62.
The ability to access and remove friction torque limiting clutch
62 from crusher 10 without removing head 30 is advantageous because
overall maintenance time is reduced. Accordingly, "top surface"
is advantageous as compared to crusher 10 designs that require removal
of head 30 to service any torque limiter housed therein.
While the detailed drawings and specific examples given describe
preferred and exemplary embodiments of the invention, they serve
the purpose of illustration only. The inventions disclosed are not
limited to the specific form shown. For example, backstop clutch
54 may have differing mechanical configurations depending on the
crusher application. Further, the linkage between backstop clutch
54 and friction torque limiting clutch 62 may differ depending on
the particular crusher application. The crusher configurations shown
and described may differ depending on the chosen performance characteristics
and physical characteristics of the rock crushers. Furthermore,
other substitutions, modifications, changes, and omissions may be
made in the design, operating conditions, and arrangement of the
exemplary embodiments without departing from the scope of the invention
as expressed in the appended claims.
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