Abstrict A gyratory crusher includes an anti-spin mechanism which is coupled
to a lower end of a main shaft of the crusher and which prevents
the main shaft and associated crushing head from spinning when the
crusher is not subject to a crushing load. The anti-spin mechanism
includes 1) a hydraulic brake, and 2) a gear train which couples
the main shaft to the hydraulic brake so as to drive the hydraulic
brake to rotate faster than the main shaft while at the same time
permitting relative sliding motion between the main shaft and the
hydraulic brake without unduly increasing the complexity or height
of the crusher. The hydraulic brake is supercharged so as to respond
immediately to a tendency of the main shaft to spin. As a result,
only relatively low braking forces are required to prevent spinning.
Claims We claim:
1. A gyratory crusher comprising:
(A) a stationary frame;
(B) a main drive gear which is mounted on said frame and which
is driven to rotate about a vertical axis;
(C) a main shaft which is rotatably supported on said main drive
gear at a location which is offset from said vertical axis so as
to rotate eccentrically with respect to said vertical axis, wherein
said main shaft rotates in a crushing direction during a crushing
operation;
(D) a crushing head mounted on said main shaft; and
(E) an anti-spin mechanism comprising a hydraulic brake, said hydraulic
brake including
(1) a source of pressurized hydraulic fluid, and
(2) a hydraulic motor which is rotationally coupled to said main
shaft and which imparts a substantial resistance to main shaft rotation
in a spinning direction which is opposite to said crushing direction,
said hydraulic motor being supercharged by said source of pressurized
hydraulic fluid so as to react essentially immediately to a tendency
of said main shaft to rotate in said spinning direction.
2. A crusher as defined in claim 1 wherein said anti-spin mechanism
further comprises a gear train operatively coupled to a lower portion
of said main shaft and to said hydraulic brake.
3. A crusher as defined in claim 2 wherein said gear train comprises
a sliding coupling to which said main shaft is slidably coupled
and which rotates with said main shaft, and
a gear reducer which rotationally couples said sliding coupling
to said hydraulic motor so that said hydraulic motor is driven by
said sliding coupling to rotate at a higher speed than said main
shaft.
4. A crusher as defined in claim 3 wherein said gear reducer effects
a speed increase of at least 5:1 with respect to the rotational
speed of said main gear.
5. A crusher as defined in claim 4 wherein said gear reducer effects
a speed increase of at least 20:1.
6. A crusher as defined in claim 5 wherein said gear reducer effects
a speed increase of about 50:1.
7. A crusher as defined in claim 3 wherein said gear reducer comprises
a differential planetary gear set having 1) a sun gear to which
said hydraulic motor is non-rotatably coupled and 2) planet gears
to which said sliding coupling is non-rotatably coupled.
8. A crusher as defined in claim 2 wherein said sliding coupling
comprises
a follower gear having upper and lower surfaces,
a tang which is fixed to said main shaft and which is coupled to
said upper surface of said follower gear so as to be fixed from
rotation with respect to said follower gear but so as to be slidable
in an X direction with respect to said follower gear, and
a driven gear which is fixed from rotation with respect to an input
element of said hydraulic motor, said lower surface of said follower
gear being coupled to an upper surface of said driven gear so as
to be fixed from rotation with respect to said driven gear but so
as to be slidable in a Y direction with respect to said driven gear,
said Y direction being perpendicular to said X direction.
9. A crusher as defined in claim 8 wherein said follower gear
is coupled to said tang and to said driven gear by respective sliding
tongue-and-groove connections.
10. A crusher as defined in claim 8 further comprising oil supply
bores formed in said tang and said follower gear to permit the supply
of lubricating oil to relatively-sliding surfaces of said tang,
said follower gear, and said driven gear.
11. A crusher as defined in claim 1 further comprising a hydraulic
circuit in which is disposed said hydraulic motor and said source
of pressurized hydraulic fluid, said hydraulic circuit imposing
minimal damping to rotation of said hydraulic motor when said main
shaft rotates in said crushing direction but imposing a substantial
damping to rotation of said hydraulic motor when said main shaft
tends to rotate in said spinning direction.
12. A crusher as defined in claim 11 wherein said hydraulic circuit
further comprises a pressure reducer disposed between said pressure
source and said hydraulic motor.
13. A crusher as defined in claim 11 wherein said hydraulic circuit
further comprises 1) a conduit into which hydraulic fluid is forced
from said hydraulic motor when said main shaft rotates in said spinning
direction, and 2) a check valve which is disposed in said conduit
and which prevents fluid flow therethrough from said hydraulic motor.
14. A crusher as defined in claim 13 wherein said hydraulic circuit
further comprises a relief valve which is disposed in parallel with
said check valve and which permits limited fluid flow around said
check valve from said hydraulic motor.
15. A crusher as defined in claim 14 wherein said relief valve
is adjustable to permit a threshold pressure to be set below which
fluid will not flow through said relief valve.
16. A gyratory crusher comprising:
(A) a stationary frame;
(B) a main drive gear which is mounted on said frame and which
is driven to rotate about a vertical axis;
(C) a main shaft which is rotatably supported on said main drive
gear at a location which is offset from said vertical axis so as
to rotate eccentrically with a central axis of rotation of said
main drive gear, said main shaft having an upper portion and having
a lower portion, wherein said main shaft rotates in a crushing direction
during a crushing operation;
(D) a crushing head mounted on said upper portion of said main
shaft; and
(E) an anti-spin mechanism comprising
(1) a hydraulic brake located in the vicinity of said lower portion
of said main shaft and operable to impose substantial resistance
to main shaft rotation in a spinning direction which is opposite
said crushing direction, and
(2) a gear train which drivingly meshes with a mating member on
said lower portion of said main shaft and which is operatively coupled
to said hydraulic brake.
17. A crusher as defined in claim 16 wherein said hydraulic brake
comprises a hydraulic motor which is driven by said main gear.
18. A crusher as defined in claim 17 further comprising a hydraulic
circuit in which said hydraulic motor is disposed, said hydraulic
circuit comprising 1) a conduit into which hydraulic fluid is forced
from said hydraulic motor when said main shaft rotates in said spinning
direction, and 2) a check valve which is disposed in said conduit
and which prevents fluid flow therethrough from said hydraulic motor.
19. A crusher as defined in claim 18 wherein said hydraulic circuit
further comprises a pressure relief valve which is disposed in parallel
with said check valve and which permits limited fluid flow around
said check valve from said hydraulic motor.
20. A gyratory crusher comprising:
(A) a stationary frame;
(B) a main drive gear which is mounted on said frame and which
is driven to rotate about a vertical axis;
(C) a main shaft which is rotatably supported on said main drive
gear at a location which is offset from said vertical axis so as
to rotate eccentrically with a central axis of rotation of said
main drive gear, said main shaft having an upper portion and having
a lower portion, wherein said main shaft rotates in a crushing direction
during a crushing operation;
(D) a crushing head mounted on said upper portion of said main
shaft; and
(E) an anti-spin mechanism comprising
(1) a hydraulic brake located in the vicinity of said lower portion
of said main shaft and operable to impose substantial resistance
to main shaft rotation in a spinning direction which is opposite
said crushing direction, and
(2) a gear train operatively coupled to said lower portion of said
main shaft and to said hydraulic brake, wherein said gear train
comprises
(a) a sliding coupling on which said main shaft is slidably coupled
and which rotates with said main shaft; and
(b) a gear reducer which rotationally couples said sliding coupling
to said hydraulic motor so that said hydraulic motor is driven by
said sliding coupling to rotate at a higher speed than said main
shaft.
21. A crusher as defined in claim 20 wherein said gear reducer
effects a speed increase of at least 5:1 with respect to the rotational
speed of said main shaft.
22. A crusher as defined in claim 21 wherein said gear reducer
comprises a planetary gear assembly having 1) a sun gear to which
said hydraulic brake is non-rotatably coupled and 2) planet gears
to which said sliding coupling is non-rotatably coupled.
23. A crusher as defined in claim 20 wherein said sliding coupling
comprises
a follower gear having upper and lower surfaces,
a tang which is fixed to said main shaft and which is coupled to
said upper surface of said follower gear so as to be fixed from
rotation with respect to said follower gear but so as to be slidable
in an X direction with respect to said follower gear, and
a driven gear which is fixed from rotation with respect to an input
element of said hydraulic brake, said lower surface of said follower
gear being coupled to an upper surface of said driven gear so as
to be fixed from rotation with respect to said driven gear but so
as to be slidable in a Y direction with respect to said driven gear,
said Y direction being perpendicular to said X direction.
24. A crusher as defined in claim 23 further comprising oil supply
bores formed in said tang and said follower gear to permit the supply
of lubricating oil to relatively-sliding surfaces of said tang,
said follower gear, and said driven gear.
25. A gyratory crusher comprising:
(A) a stationary frame;
(B) a main drive gear which is mounted on said frame and which
is driven to rotate about a vertical axis;
(C) a main shaft which is rotatably supported on said main drive
gear at a location which is offset from said vertical axis so as
to rotate eccentrically with respect to said vertical axis, wherein
said main shaft has upper and lower portions, and wherein said main
drive shaft rotates in a crushing direction during a crushing operation;
(D) a crushing head mounted on said upper portion of said main
shaft; and
(E) an anti-spin mechanism comprising a hydraulic brake, said hydraulic
brake including
(1) a gear train including
(a) a sliding coupling to which said main shaft is slidably coupled
and which rotates with said main shaft, said sliding coupling including
(i) a follower gear having upper and lower surfaces,
(ii) a tang which is fixed to said lower portion of said main shaft
and which is coupled to said upper surface of said follower gear
by a first tongue and groove connection so as to be fixed from rotation
with respect to said follower gear but so as to be slidable in an
X direction with respect to said follower gear, and
(iii) a driven gear which is coupled to said lower surface of said
follower gear by a second tongue and groove connection so as to
be fixed from rotation with respect to said driven gear but so as
to be slidable in a Y direction with respect to said driven gear,
said Y direction being perpendicular to said X direction, wherein
oil supply bores are formed in said tang and said follower gear
to permit the supply of lubricating oil to relatively-sliding surfaces
of said tang, said follower gear, and said driven gear, and
(b) a gear reducer which rotationally couples said driven gear
to said hydraulic motor so that said hydraulic motor is driven by
said sliding coupling to rotate at a higher speed than said sliding
coupling, said gear reducer comprising a differential planetary
gear set having i) planet gears to which said driven gear is non-rotatably
coupled, and ii) a sun gear,
(2) a hydraulic motor which is non-rotatably coupled to said sun
gear and which imparts a substantial resistance to main shaft rotation
in a spinning direction which is opposite to said crushing direction,
and
(3) a hydraulic circuit including,
(a) a source of pressurized hydraulic fluid which supercharges
said hydraulic motor so that said hydraulic motor reacts essentially
immediately to a tendency of said main shaft to rotate in said spinning
direction to damp rotation of said main shaft in said spinning direction,
(b) a conduit into which hydraulic fluid is forced from said hydraulic
motor when said main shaft rotates in said spinning direction,
(c) a check valve which is disposed in said conduit and which prevents
fluid flow therethrough from said hydraulic motor, and
(d) a relief valve which is disposed in parallel with said check
valve and which permits limited fluid flow around said check valve
from said hydraulic motor.
26. A method comprising:
(A) providing a gyratory crusher including a stationary frame,
a main drive gear rotatably mounted on said frame, and a main shaft
which is mounted on said main drive gear so as to be rotatable about
an axis which is offset from a central axis of said drive gear;
(B) driving said main drive gear to rotate;
(C) permitting said main shaft to rotate about its axis in a crushing
direction during a crushing operation in which rock is being crushed
by said crusher; and
(D) selectively braking said main shaft by imparting a substantial
resistance to main shaft rotation in a spinning direction which
is opposite to said crushing direction, the resistance being imposed
by a hydraulic motor which is supercharged by a source of pressurized
hydraulic fluid so as to react essentially immediately to a tendency
of said main shaft to rotate in said spinning direction.
27. A method as defined in claim 26 wherein said hydraulic motor
is coupled to said main shaft by a gear train which permits sliding
movement of said main shaft relatively to said hydraulic motor while
preventing relative rotational movement between said hydraulic motor
and said main shaft.
28. A method as defined in claim 27 wherein said gear train couples
said hydraulic motor to said main shaft so that said hydraulic motor
rotates at a higher rotational speed than said main shaft.
29. A method as defined in claim 28 wherein said hydraulic motor
rotates at about fifty times the rotational speed of said main shaft.
30. A method as defined in claim 26 further comprising reducing
the pressure of hydraulic fluid flowing from said source of pressurized
hydraulic fluid to said hydraulic motor.
31. A method as defined in claim 26 wherein the braking step comprises
1) forcing hydraulic fluid into a conduit from said hydraulic motor
when said main shaft rotates in said spinning direction, and 2)
preventing fluid flow through said conduit via operation of a check
valve which is disposed in said conduit.
32. A method as defined in claim 31 further comprising permitting
limited hydraulic fluid flow around said check valve when hydraulic
pressure in said conduit exceeds a threshold value.
33. A method as defined in claim 32 wherein said threshold value
is adjustable.
Description BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to gyratory crushers and, more particularly,
to gyratory crushers of the type having a crushing head mounted
on an eccentric main shaft and incorporating a mechanism to prevent
the main shaft and crushing head from spinning in the absence of
a crushing load.
2. Discussion of the Related Art
Gyratory or cone crushers (sometimes known as gyrasphere crushers)
are well known for crushing stone. A typical gyratory crusher includes
1) a stationary frame, 2) a generally conical crushing head mounted
for rotation about an eccentric main shaft and including an upwardly
facing convex crushing surface, and 3) an annular crusher bowl or
concave that is mounted in the frame above the crushing head so
as to define a crushing gap forming an annular crushing chamber.
Eccentric rotation of the main shaft is effected by rotatably mounting
the shaft on the crusher's main drive gear or bull gear on an axis
which is offset from and inclined with respect to the axis of rotation
of the main drive gear.
During a crushing operation, the crushing head, through the material
being crushed, is placed in rolling engagement with the concave
or crusher bowl and thus rotates, relative to the stationary frame
and the main drive gear, in a direction opposite to the direction
of main drive gear rotation. The crushing head and main shaft are
mounted so as to be freely rotatable within the main drive gear
to accommodate such relative rotation. However, in the absence of
a crushing load, the crushing head tends to "spin" or
rotate in the same direction and at the same speed as the main drive
gear. When material to be crushed is fed into the crushing cavity
and contacts the freely spinning crushing head, the material detrimentally
abrades the crushing head and also the concave, both of which are
typically formed from a relatively soft manganese liner. Initial
contact between the stone or other materials to be crushed and the
freely spinning head also can result in ejection of small and even
some relatively large stones from the crusher, risking damage to
external components of the crusher or injury to personnel in the
vicinity of the crusher.
Many so-called "anti-spin" mechanisms have been proposed
to eliminate or at least inhibit free spinning of an unloaded crushing
head. Examples of such anti-spin mechanism are disclosed in U.S.
Pat. No. 3207449 to Johnson; 3743193 to DeDiemar et al.; U.S.
Pat. No. 3750809 to DeDiemar et al.; U.S. Pat. No. 4206881 to
Werginz; U.S. Pat. No. 4467971 to Schuman; and U.S. Pat. No. 4666092
to Bremer. All of these patents disclose anti-spin mechanisms employing
hydraulic brakes or some other device located near the upper end
of the main shaft, i.e., within the crushing head, to resist or
prevent crushing head spinning. The anti-spin mechanisms disclosed
in all of these patents therefore are incompatible or at least ill-suited
for use with a solid main shaft or one lacking a large internal
axial bore.
Apart from problems of complexity and incompatibility with many
eccentric shafts, another problem associated with many of the anti-spin
mechanisms disclosed by the patents listed above is that the length
of the main shaft and associated drive elements must be increased
substantially to accommodate the anti-spin mechanism, leading to
a significant increase in the overall axial height of the crusher.
This represents a problem because crushers form but one component
of a quarry system and must be sized to be compatible with augers,
elevators, and conveyors commonly employed in quarry systems.
Still another problem associated with the anti-spin mechanisms
disclosed in many of the patents listed above is that they are not
very robust and cannot survive the severe vibrations and shock loads
imposed on the mechanisms during crushing for prolonged periods
of time. Moreover, many of these mechanisms are relatively inaccessible
and difficult to install initially and to replace when they fail.
Yet another problem associated with many heretofore available anti-spin
mechanisms is that they can never permit rotation of the main shaft
and crushing head in the same direction that the main drive or bull
gear rotates. Accordingly, if the crushing head becomes jammed due,
e.g, to the introduction of non-crushable materials (known as tramp)
into the crusher, the anti-spin mechanism and/or other components
of the crusher are destroyed.
Some of these problems can be understood by a more detailed review
of specific prior art references.
For instance, an overrunning clutch-based anti-spin mechanism is
disclosed in the Johnson patent. The overrunning clutch is connected
to the main shaft by a sliding coupling that permits relative sliding
movement between the main shaft and the overrunning clutch but that
prohibits relative rotational movement therebetween. The overrunning
clutch includes 1) an input shaft coupled to the head and 2) a one-way
clutch element that is coupled to the input shaft and that permits
main shaft rotation in the crushing direction while prohibiting
main shaft rotation in the spinning direction.
The anti-spin mechanism disclosed in the Johnson patent exhibits
notable drawbacks. For instance, the sliding coupling is located
within the upper portion of the crushing head and hence is incompatible
for use with a solid main shaft or one lacking a large internal
axial bore. Moreover, the one-way clutch element is incapable of
permitting main shaft rotation in the spinning direction. A separate
brake or shear pin therefore must be provided to permit shaft rotation
in the spinning direction in the event that tramp becomes lodged
in the crushing gap.
An exemplary hydraulic brake is disclosed in the Werginz '881 patent.
The Werginz '881 patent discloses a main shaft that is rotationally
coupled to a bidirectional hydraulic motor. The hydraulic motor
is disposed in a hydraulic circuit including 1) an unpressurized
reservoir (typically filled with lubricating oil also used to lubricate
the main shaft and other components of the crusher), 2) a check
valve, and 3) a relief valve. Rotation of the main shaft in the
crushing direction causes oil to circulate from the reservoir upwardly
through the check valve and back to the reservoir without imparting
any substantial resistance to hydraulic motor rotation. However,
hydraulic motor rotation in the opposite direction is resisted by
the check valve which prevents fluid flow through the circuit in
that direction. Limited fluid flow around the check valve is possible
only when the fluid pressure generated by the rotating motor exceeds
a value at which the relief valve opens, thereby permitting limited
motor rotation and preventing damage to the hydraulic brake in the
event that the crushing head becomes jammed by tramp.
While the hydraulic brake disclosed in the Werginz '881 patent
is generally effective, it is relatively slow to react to main shaft
spinning due to the fact that the hydraulic fluid is not pressurized
before it is drawn into the hydraulic motor. Motor leakage and other
factors therefore permit an air cushion to form at the inlet side
of the hydraulic motor. This air cushion delays the response of
the hydraulic motor to main shaft spinning because the hydraulic
motor can rotate in the spinning direction until the air cushion
is eliminated. By this time, the main shaft has built up substantial
inertia and hence requires higher braking forces then would be required
if shaft rotation in the spinning direction is prevented altogether.
The hydraulic motor therefore must be oversized. In addition, the
risk of damage to crusher components is increased because substantial
shock loads are imposed on those components during rapid deceleration
of the rotating main shaft. At least some of these problems are
exacerbated by the fact that the hydraulic motor is rotating at
the same low velocity as the main shaft (typically about 10-20 RPM)
and cannot always generate adequate pressure for effective braking.
OBJECTS AND SUMMARY OF THE INVENTION
It is therefore a primary object of the invention to provide a
gyratory crusher having an anti-spin mechanism which reacts immediately
to a tendency of the crusher's main shaft to spin so that spinning
is actually prevented as opposed to braked after it begins.
In accordance with a first aspect of the invention, this object
is achieved by providing a gyratory crusher comprising, a stationary
frame, a main drive gear which is mounted on the frame and which
is driven to rotate about a vertical axis, a main shaft, a crushing
head mounted on the main shaft, and an anti-spin mechanism. The
main shaft 1) is rotatably supported on the main drive gear at a
location which is offset from the vertical axis so as to rotate
eccentrically with respect to the vertical axis, and 2) rotates
in a crushing direction during a crushing operation. The anti-spin
mechanism comprises a hydraulic brake which includes a source of
pressurized hydraulic fluid and a hydraulic motor. The hydraulic
motor is rotationally coupled to the main shaft and imparts a substantial
resistance to main shaft rotation in a spinning direction which
is opposite to the crushing direction. The hydraulic motor is supercharged
by the source of pressurized hydraulic fluid so as to react essentially
immediately to a tendency of the main shaft to rotate in the spinning
direction.
Preferably, the anti-spin mechanism further comprises a gear train
operatively coupled to a lower portion of the main shaft and to
the hydraulic brake. The gear train preferably comprises 1) a sliding
coupling to which the main shaft is slidably coupled and which rotates
with the main shaft, and 2) a gear reducer which rotationally couples
the sliding coupling to the hydraulic motor so that the hydraulic
motor is driven by the sliding coupling to rotate at a higher speed
than the main shaft.
The crusher preferably also comprises a hydraulic circuit in which
is disposed the hydraulic motor and the source of pressurized hydraulic
fluid. The hydraulic circuit imposes minimal damping to rotation
of the hydraulic motor when the main shaft rotates in the crushing
direction but imposes a substantial damping to rotation of the hydraulic
motor when the main shaft tends to rotate in the spinning direction.
Preferably, the hydraulic circuit further comprises 1) a conduit
into which hydraulic fluid is forced from the hydraulic motor when
the main shaft rotates in the spinning direction, and 2) a check
valve which is disposed in the conduit and which prevents fluid
flow therethrough from the hydraulic motor.
Another object of the invention is to provide an anti-spin mechanism
that meets the first principal object and that still permits rotation
of the main shaft in its spinning direction under limited circumstances
to prevent damage to system components due to crushing head jamming
or due to overly rapid deceleration of the crushing head.
In accordance with another object of the invention, this object
is achieved by providing a relief valve which is disposed in parallel
with the check valve and which permits limited fluid flow around
the check valve from the hydraulic motor. The relief valve preferably
is adjustable to permit a threshold pressure to be set below which
fluid will not flow through the relief valve.
Another object of the invention is to provide an anti-spin mechanism
which meets the first principal object and which requires minimal
modifications to crusher design for its implementation.
Another object of the invention is to provide an anti-spin mechanism
which has the characteristics discussed above and which is relatively
robust.
Still another object of the invention is to provide an anti-spin
mechanism which exhibits one or more of the characteristics discussed
above and which is relatively easy to install and replace.
In accordance with yet another aspect of the invention, these objects
are achieved by coupling an anti-spin mechanism, preferably one
employing a hydraulic brake, to the lower end of the main shaft.
A second principal object of the invention is to provide an improved
method of preventing a main shaft of a gyratory crusher from spinning.
In accordance with still another aspect of the invention, this
object is achieved by 1) providing a method comprising providing
a gyratory crusher including a stationary frame, a main drive gear
rotatably mounted on the frame, and a main shaft which is mounted
on the main drive gear so as to be rotatable about an axis which
is offset from a central axis of the drive gear, driving the main
drive gear to rotate, 2) permitting the main shaft to rotate about
its axis in a crushing direction during a crushing operation in
which rock is being crushed by the crusher, and 3) selectively braking
the main shaft. The braking step includes imparting a substantial
resistance to main shaft rotation in a spinning direction which
is opposite to the crushing direction. The resistance is imposed
by a hydraulic motor which is supercharged by a source of pressurized
hydraulic fluid so as to react essentially immediately to a tendency
of the main shaft to rotate in the spinning direction.
Preferably, in order to further increase reaction speed, the hydraulic
motor is coupled to the main shaft by a gear train which couples
the hydraulic motor to the main shaft so that the hydraulic motor
rotates at a higher speed than the main shaft. The hydraulic motor
preferably rotates at about fifty times the rotational speed of
the main shaft.
Preferably, the braking step comprises 1) forcing hydraulic fluid
into a conduit from the hydraulic motor when the main shaft rotates
in the spinning direction, and 2) preventing fluid flow through
the conduit via operation of a check valve which is disposed in
the conduit. Limited hydraulic fluid flow preferably is permitted
around the check valve when hydraulic pressure in the conduit exceeds
a threshold value.
Other objects, features, and advantages of the present invention
will become apparent to those skilled in the art from the following
detailed description and the accompanying drawings. It should be
understood, however, that the detailed description and specific
examples, while indicating preferred embodiments of the present
invention, are given by way of illustration and not of limitation.
Many changes and modifications may be made within the scope of the
present invention without departing from the spirit thereof, and
the invention includes all such modifications.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred exemplary embodiment of the invention is illustrated
in the accompanying drawings in which like reference numerals represent
like parts throughout, and in which:
FIG. 1 is a sectional side elevation view of a gyratory crusher
constructed in accordance with a preferred embodiment of the invention;
FIG. 2 is an enlarged sectional elevation view of a portion of
the crusher of FIG. 1 and illustrating an anti-spin mechanism of
the crusher in greater detail;
FIG. 3 is a sectional end view taken generally along the lines
3--3 in FIG. 2;
FIG. 4 is a sectional end view taken generally along the lines
4--4 in FIG. 2;
FIG. 5 is a sectional end view taken generally along the lines
of 5--5 in FIG. 2;
FIG. 6 is a fragmentary perspective view of a portion of a gear
train of the anti-spin mechanism;
FIG. 7 is an exploded perspective view of a portion of the gear
train; and
FIG. 8 is a schematic hydraulic circuit of the crusher of FIG.
1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
1. Resume
Pursuant to the invention, a gyratory crusher is provided with
an anti-spin mechanism which is coupled to a lower end of a main
shaft of the crusher and which prevents the main shaft and associated
crushing head from spinning when the crusher is not subject to a
crushing load. The anti-spin mechanism includes 1) a hydraulic brake,
and 2) a gear train preferably couples the main shaft to the hydraulic
brake so as to drive the hydraulic brake to rotate faster than the
main shaft while at the same time permitting relative sliding motion
between the main shaft and the hydraulic brake without unduly increasing
the complexity or height of the crusher. The hydraulic brake is
supercharged (i.e., supplied with pressurized hydraulic fluid from
a separate source) so as to respond immediately to a tendency of
the main shaft to spin. As a result, only relatively low braking
forces are required to prevent spinning.
2. System Overview and Construction of Anti-Spin Mechanism
Referring now to the drawings and to FIG. 1 in particular, a gyratory
or cone crusher 10 (sometimes known as a gyrasphere crusher) is
illustrated. Crusher 10 includes a main crusher frame 12 having
upper and lower portions 14 and 16 a crushing head 18 mounted on
the crusher frame lower portion 16 and a crusher bowl 20 mounted
on the crusher frame upper portion 14 above the crushing head 18.
The crusher bowl 20 is normally held fast from rotation with respect
to the crusher frame upper portion 14 by a bowl lock assembly 22
but the bowl lock assembly 22 is selectively releasable using cylinders
154 (FIG. 8) to permit vertical adjustment of the bowl 20 relative
to the head 18 using a bowl adjuster mechanism 24 actuated by adjusting
cylinders 156 (FIG. 8). Rotation of the crushing head 18 is controlled
by a drive mechanism 26 and by an anti-spin mechanism 28 detailed
in Section 3. below.
The crushing head 18 is fixedly mounted on the upper end 34 of
a main shaft 30 and is generally frusto-conical in shape. The outer,
crushing portion or mantle of the crushing head 18 is formed from
a replaceable manganese liner 32 threaded onto the upper end 34
of the main shaft 30 as illustrated in FIG. 1. The main shaft 30
is mounted on a main drive or bull gear 36 comprising a bevel gear
driven by the drive mechanism 26. The drive mechanism 26 comprises
1) a spur gear 38 meshing with the main drive gear 36 2) a horizontal
input shaft or countershaft 40 journaled in the crusher frame lower
portion 16 and connected at its inner end to the gear 38 and 3)
a sheave 42 mounted on the outer end of the countershaft 40 and
driven in a conventional manner.
A generally tubular support member 44 is fixed to the main drive
gear 36 and extends upwardly therefrom so as to be rotatably journaled
in the crusher frame lower portion 16 by bearings 46. The main shaft
30 extends through the tubular support member 44 on an axis 48 which
is offset from and inclined with respect to the axis of rotation
50 of the main drive gear 36 and is supported in the tubular support
member 44 by a bearing sleeve 45. The crushing head 18 and thus
the shaft 30 are rotatably supported on the tubular support member
44 by upper bearings 52. The main shaft 30 is of a type which is
either solid or has only relatively small lubrication bores formed
axially therethrough for the purpose of permitting and limiting
flow of lubricating fluid to the bearings 46 52. It is important
to note that this and similar eccentric shafts cannot support hydraulic
brakes or other anti-spin mechanisms at their upper ends.
The crusher bowl 20 includes a body or frame 54 an upper uncrushed
and/or pre-crushed rock feed hopper 56 and a lower concave surface
58 (often referred to as "a concave") which is formed
from a replaceable manganese liner. Concave surface 58 surrounds
the manganese liner 32 forming the convex crushing surface of the
crushing head 18 and is spaced above it to define a crushing gap
G having a thickness which varies around the circumference of the
crushing head 18 due to the eccentric mounting of the eccentric
shaft 30 and the crushing head 18 on the main drive gear 36. In
order to permit vertical adjustment of the crusher bowl 20 relative
to the crusher frame 12 and thus to permit adjustment of the thickness
of the gap G, a helically threaded connection is provided between
the crusher bowl 20 and the frame upper portion 14 to permit vertical
adjustment of the bowl 20 relative to the frame upper portion 14.
The bowl 20 is normally locked from rotation with respect to the
frame upper portion 14 by the bowl lock assembly 22 but the bowl
lock assembly 22 can be selectively released to permit rotation
of the crusher bowl 20 relative to the frame 12 for gap adjustment
purposes, under the action of the adjuster mechanism 24 in a manner
which is, per se, well known. The crusher frame upper portion 14
is connected to the crusher frame lower portion 16 by a plurality
of tramp relief cylinders 60 which can be selectively actuated to
lift the crusher frame upper portion 14 for tramp relief purposes
in a conventional manner.
3. Construction of Anti-Spin Mechanism
The gyratory or cone crusher 10 as thus far described (save for
the brief description of the anti-spin mechanism 28) would operate
acceptably except for the fact that the crushing head 18 and main
shaft 30 would spin in the absence of a crushing load due to the
fact that the main shaft 30 is rotatably journaled in the main drive
gear or bull gear 36 and due to the fact that the main drive gear
36 rotates at a relatively high rate, typically about 300-400 rpm.
Crushing head spinning is undesirable because, upon initiation of
a crushing action, contact between the stone and the rapidly spinning
crushing head 18 would rapidly abrade and prematurely wear the manganese
liner 32. Moreover, contact between the stones and the rapidly spinning
crushing head 18 could cause at least some of the stones to be thrown
out of the crusher 10 and risk damage to the crusher 10 or possible
injury to personnel in the surrounding area. Crushing head spinning
also would tend to channel rocks towards the widest point of the
crushing gap G and cause many smaller stones to fall through the
crushing chamber without being crushed. It is for these reasons
that an anti-spin mechanism is desirable and that the inventive
anti-spin mechanism 28 is provided.
The anti-spin mechanism 28 is designed to prevent undesired crushing
head spinning in the absence of a crushing load by reacting immediately
to a tendency of the main shaft 30 to spin rather than by braking
a spinning main shaft. Inertial loads on the main shaft 30 therefore
are reduced. The anti-spin mechanism 28 also is designed to permit
main shaft rotation in the spinning direction in the event that
the crushing head 18 becomes jammed by tramp or in the event that
rapid main shaft deceleration would place undue shock loads on the
main shaft 30 and the anti-spin mechanism 28.
Towards these ends, and referring particularly to FIGS. 2 and 7
the anti-spin mechanism 28 includes as its principal components
1) a supercharged hydraulic brake 62 and 2) a gear train 64 coupling
the hydraulic brake 62 to the main shaft 30. The anti-spin mechanism
28 is encased in fluid-tight housing 66 supported by the bottom
surface of the crusher frame lower portion 16 via an adapter plate
68 described below. The gear train 64 and hydraulic brake 62 will
be described in turn.
The gear train 64 performs several functions. First, it rotationally
couples a hydraulic motor 146 of the hydraulic brake 62 to the main
shaft 30 while accommodating eccentric movement of the main shaft
30 relative to the hydraulic motor 146. Second, it effects a torque
reduction and speed increase so that the hydraulic motor 146 rotates
at a higher speed than the main shaft 30. This speed increase is
beneficial because the main shaft 30 typically rotates at a relatively
slow speed, usually about 5% of the speed of the main drive gear
36 or about 17 rpm and because most hydraulic motors do not pump
efficiently at such low speeds.
The gear train 64 is supported on the crusher mainframe lower portion
16 by a support assembly including an adapter plate 68 and a driven
gear retainer bearing 70. As best seen in FIGS. 2 6 and 7 the
adapter plate 68 is attached directly to the crusher frame lower
portion 16 by a plurality of bolts 69 spaced around the periphery
of the adapter plate 68. The driven gear retainer bearing 70 1)
is attached to the bottom surface of the adapter plate 68 by bolts
71 and 2) supports the gear train 64 as detailed below.
The gear train 64 includes as its major components a sliding coupling
72 and a gear reducer 74. Each of these components now will be discussed
in turn.
The purpose of the sliding coupling 72 is to prevent relative rotation
between the hydraulic motor 146 and the main shaft 30 while permitting
relative sliding movement therebetween to accommodate eccentric
rotation of the main shaft 30 relative to the hydraulic motor 146.
Referring particularly to FIGS. 2-4 and 7 the sliding coupling
72 includes as its principal components a tang 76 a follower gear
78 and a driven gear 80.
The tang 76 is fixed to the bottom end of the main shaft 30 at
its upper end and mates with the follower gear 78 at its lower end
so as to prevent relative rotation between the tang 76 and the follower
gear 78 while permitting sliding movement therebetween in an "X"
direction. The tang 76 is attached to the bottom end of the main
shaft 30 by a plurality of bolts 82 that extend through through-bores
84 in the tang 76 and that are threaded into tapped bores 86 in
the lower end of the main shaft 30 as best seen in FIG. 7. Cross
channels 88 are formed in the upper surface of the tang 76 so as
to direct lubricating oil from axial bores 90 in the main shaft
30 to a radially-central, axially-extending receptacle 92 in the
tang 76 that is best seen in FIG. 2 and that acts as a funnel for
channeling lubricating oil to a lubricating bore 94. The lubricating
oil is the same oil used to lubricate relative motion between the
main shaft 30 and the surrounding tubular support 44 and outer sleeve
45. A downwardly-extending tongue 96 is formed in the bottom surface
of the tang 76 and mates with a complimentary groove 98 formed in
the upper surface of the follower gear 78. It is this tongue-and-groove
connection that fixes the follower gear 78 from rotation with respect
to the tang 76 while permitting relative sliding motion therebetween.
This sliding motion is facilitated by lubricating oil supplied to
the groove 98 by the lubricating bore 94 which extends downwardly
from the receptacle 92 to the bottom of the tongue 96 as best seen
in FIG. 2.
As best seen in FIGS. 4 6 and 7 the follower gear 78 and driven
gear 80 are received in a central aperture 100 of the adapter plate
68 such that the follower gear 78 rests upon and rotates with the
driven gear 80. The driven gear 80 in turn rests on the driven gear
retainer bearing 70 as best seen in FIG. 2 so as to slidably rotatable
with respect thereto. A tongue 104 is formed on the upper surface
of the driven gear 80 for mating with a bottom groove 102 on the
follower gear 78 so as to permit sliding movement of the follower
gear 78 relative to the driven gear 80 in a "Y" direction
which is perpendicular to the "X" direction while preventing
relative rotational movement therebetween.
Sliding movement between the follower gear 78 and the driven gear
80 is facilitated by lubricating oil. The lubricating oil is supplied
to the lower tongue-and-groove connection 102 and 104 via 1) an
axial through-bore 106 formed in the follower gear 78 that receives
oil from the lubricating bore 94 in the tang 76 and 2) additional
axial bores 108 in the follower gear 78 that mate with reservoirs
110 that are formed on the upper surface of the follower gear 78
at opposite sides of the groove 102 and that receive lubricating
oil directly from the main shaft 30.
The gear reducer 74 serves an important function. Specifically,
it steps up the speed of the hydraulic motor 146 relative to the
main shaft 30 so that the hydraulic motor 146 rotates at a sufficiently-high
velocity to provide effective main shaft braking without having
to over-size the hydraulic motor 146. At the same time, it reduces
the torque supplied to the hydraulic motor 146 by the main shaft
30 to reduce motor wear and to inhibit early failure. The torque
reduction and speed increase should be at least 5:1 and preferably
at least 20:1 and most preferably are about 50:1. This speed increase
and accompanying torque reduction could be achieved via a variety
of mechanisms. However, a differential planetary gear set is preferred
because 1) it is simple, 2) it is compact so as to not unduly increase
the overall length of the crusher, and 3) it is robust. The gear
reducer 74 therefore will hereafter be referred to as a "differential
planetary gear set."
As best seen in FIGS. 2 and 5 the differential planetary gear
set 74 is coupled to the sliding coupling 72 by a torque shaft 130
having a splined upper end 132 mating with a splined bore 134 in
the driven gear 80 and having a gear 136 on its lower end. The differential
planetary gear 74 set includes a ring 120 a plurality of planet
gears 122 and a sun gear 124 all contained in a housing 126. The
housing 126 is attached to the bottom surface of the driven gear
retainer bearing 70 via a plurality of bolts (not shown) extending
through an annular flange 128 of the housing 126.
The ring 120 is press-fit or otherwise fixed to the interior periphery
of the housing 126 and meshes with the planet gears 122. The planet
gears 122 (three of which are provided in the illustrated embodiment)
are spaced peripherally about the differential planetary gear set
74 with each planet gear 122 including upper and lower toothed portions
138 and 140 one of which meshes with the gear 136 on the torque
shaft 130 and the other of which meshes with the sun gear 124. The
sun gear 124 has a splined interior aperture 142 meshing with splines
on an input shaft 144 for the hydraulic motor 146. Accordingly,
torque is transmitted 1) from the driven gear 80 to the torque shaft
130 2) from the torque shaft 130 to the upper toothed portion 138
of the planet gears 122 3) from the lower toothed portion 140 of
the planet gears 122 to the sun gear 124 and 4) from the sun gear
124 to the input shaft 144 for the hydraulic motor 146. The ring
gear 120 planet gears 122 and sun gear 124 are dimensioned relative
to one another to provide the desired torque reduction and speed
increase. Hence, when all is said and done, the hydraulic motor
146 is driven to rotate at fifty times the speed of the main shaft
30 and in the same direction.
The hydraulic brake 62 may comprise any device capable of achieving
the above-described unidirectional hydraulic braking but preferably
includes a supercharged bidirectional hydraulic motor 146 which
assuredly provides essentially instantaneous response to main shaft
spinning. The hydraulic motor 146 best seen in FIGS. 2 and 7 is
a conventional hydraulic motor 146 which is attached to the bottom
surface of the differential planetary gear set housing 126 by bolts
148. Motors of this type usually are driven to rotate by another
power source to generate hydraulic pressure for system components.
However, when incorporated into a proper hydraulic circuit, the
hydraulic motor 146 actually becomes a brake because the circuit
resists motor rotation in the spinning direction. A hydraulic circuit
suitable for this purpose could be self-contained but preferably
forms a subcircuit of the crusher's main hydraulic circuit so as
to be supercharged by the source of pressurized hydraulic fluid
for the crusher's hydraulic circuit. A crusher hydraulic circuit
150 incorporating such a subcircuit 152 now will be described.
Referring now to FIG. 8 the crusher circuit 150 includes 1) the
hydraulic brake subcircuit 152 2) the tramp relief cylinders 60
3) the concave unlock cylinders 154 and the concave adjusting cylinders
156 all supplied with pressurized hydraulic fluid via a source
of pressurized hydraulic fluid 158. The source 158 preferably includes,
inter alia, a high-pressure pump 160 and a control valve 162 of
the type commonly found in gyratory crushers. The concave adjusting
cylinders 156 and the concave unlock cylinders 154 are selectively
supplied with pressurized hydraulic fluid from the source 158 and
vented to a reservoir 166 via operation of solenoid-actuated valves
168 170 and 172 in a manner which is, per se, known to those skilled
in the art. As is also well known to those skilled in the art, the
tramp relief cylinders 60 are controlled by a solenoid-actuated
tramp relief valve 174 switchable between 1) the illustrated neutral
position, 2) a "crush" position represented by the left
portion of the valve 174 and 3) a "clear" position represented
by the right portion of the valve 174. The valve 174 is placed in
its "crush" position during normal operation so that the
valve 174 supplies pressurized hydraulic fluid to a main supply
line 176 from the source 158 at full system pressure of, e.g., 1800-2200
psi. This supply line 176 also serves as a supercharging input line
for the hydraulic brake subcircuit 152 which will now be detailed.
The hydraulic brake subcircuit 152 includes 1) a reservoir 166
(which typically is the same reservoir used by other components
of the crusher hydraulic circuit 150), 2) the hydraulic motor 146
and 3) first and second conduits 178 and 180 connected to first
and second pump orifices 182 and 184 of the hydraulic motor 146.
The first conduit 178 connects the first pump orifice 182 to the
main supply line 176 via a pressure reducing valve 186 that reduces
the pressure in the first conduit 178 from system pressure of, e.g.,
1800-2200 psi to a much lower working pressure of about 50 psi.
The second conduit 180 connects the first conduit 178 to the second
pump orifice 184 of the hydraulic motor 146. A check valve 188 is
disposed in the second conduit 180 to permit fluid to circulate
through the subcircuit 152 when the hydraulic motor 146 rotates
in one direction but to prevent reverse fluid flow therethrough
when the hydraulic motor 146 rotates in the opposite direction.
A pressure relief valve 190 is disposed in parallel with the check
valve 188 for reasons that will become apparent below. A third conduit
192 is also provided to serve as a bleed conduit which drains fluid
that leaks from a drain port 194 of the hydraulic motor 146 to the
reservoir 166.
The hydraulic brake subcircuit 152 operates as follows:
Counterclockwise rotation of the main shaft 30 under a crushing
load drives the hydraulic motor 146 to rotate counterclockwise as
illustrated in FIG. 8. This counterclockwise rotation produces essentially
uninhibited hydraulic fluid flow from the first pump orifice 182
of the hydraulic motor 146 through the check valve 188 and into
the second pump orifice 184 in a continuous cycle so that motor
rotation is not resisted or damped by hydraulic pressure. Conversely,
if the main shaft 30 tends to spin, the hydraulic motor 146 will
attempt to rotate clockwise as seen in FIG. 8. This attempt at clockwise
rotation will force hydraulic fluid into the second conduit 180
from the second pump orifice 184 but fluid flow through the second
conduit 180 is prevented by the check valve 188. As a result, pressure
in the conduit 180 and the second pump orifice 184 increases rapidly
to brake motor rotation. Compression of the oil during this operation
provides a cushioning effect that reduces shock on system components
when compared to shocks imposed by mechanical-based systems such
as an overrunning clutch.
Immediate reaction to and braking of clockwise rotation of the
hydraulic motor 146 is assured by the supercharging effect achieved
by the supply of pressurized hydraulic fluid to the first pump orifice
182 from the main supply line 176 and the pressure reducing valve
186 which thereby assures that the hydraulic motor 146 is always
fully charged. In the absence of this supercharging effect, an air
cushion could build up within the hydraulic motor 146 so that substantial
clockwise motor rotation would occur before the air cushion is eliminated
and the hydraulic motor 146 generates sufficient fluid pressure
at the second pump orifice 184 to resist additional motor rotation.
During this time, substantial rotational inertias would accumulate
so that substantially higher braking forces would be required to
arrest movement of the rotating main shaft 130 than would be required
to prevent rotation of a stationary main shaft. A substantially
smaller and less expensive hydraulic motor 146 therefore can be
utilized than would otherwise be required. Moreover, shocks to the
main shaft 30 gear train 64 and hydraulic motor 146 that would
otherwise result from braking the rotating shaft 30 are eliminated
with resultant reduction in component wear and extension of component
life. Supercharging is also important for replenishing oil loss
to the hydraulic motor 146 due to internal leakage, which is a normal
characteristic of components of hydraulic systems of this type.
However, the brake subcircuit 152 sometimes must permit the hydraulic
motor 146 to rotate in the direction of main shaft spinning, either
because the supercharging effect is imperfect or because an externally-applied
force beyond inertial forces physically drives the main shaft 30
to rotate in the spinning direction. If not accounted for, the momentary
pressure rise occurring upon this motor rotation in the spinning
direction could either 1) damage the hydraulic motor 146 the check
valve 188 or the second conduit 180 or 2) decelerate the main shaft
30 and gear train 64 so rapidly that these components are damaged.
These potential drawbacks are eliminated by the inclusion of the
pressure relief valve 190 which permits hydraulic fluid to bypass
the check valve 188 when the pressure in the conduit 180 exceeds
a preset threshold pressure. Preferably, this threshold pressure
can be adjusted by adjustment of the relief valve 190. The pressure
relief valve 190 therefore eliminates the need for a shear bolt
which is current industry practice in mechanical-based systems.
4. Operation of Anti-Spin Mechanism
In operation, the main drive gear or bull gear 36 is driven by
the sheave 42 countershaft 40 and gear 38 to rotate clockwise
at a designated speed, typically about 350 rpm. When stones are
fed into the crusher 10 to initiate a crushing operation, contact
between the stones and the clockwise-revolving crushing head 18
imparts a counterclockwise torque to the crushing head 18 and main
shaft 30. Counterclockwise rotation of the main shaft 30 results
in a corresponding counterclockwise rotation of the hydraulic motor
146 at a speed increase ratio of 5:1 to 50:1. This rotation occurs
without any substantial hydraulic damping due to the fact that pressurized
hydraulic fluid merely flows from the first pump orifice 182 through
the check valve 188 and into the second pump orifice 184 in a continuous
loop as seen in FIG. 8.
When crushing ceases, the crushing head 18 will slow and stop and
then tend to spin or rotate clockwise. As soon as this rotation
commences, corresponding clockwise rotation of the hydraulic motor
146 quickly compresses hydraulic fluid in the second conduit 180
of the brake subcircuit 152 and increases the pressure at the second
pump orifice 184 of the hydraulic motor 146 to a level that imparts
resistance to the hydraulic motor 146 to arrest the motor 146 from
rotation and hence to prevent the main shaft 30 from spinning. If
a piece of tramp becomes lodged between the crushing head 18 and
the concave surface 58 during crushing, the crushing head 18 will
be forced to rotate clockwise until the tramp release cylinder 60
can open the crusher 10 to permit the tramp to fall out of the crushing
chamber. This rotation is permitted by the pressure relief valve
190 which allows pressurized fluid to bypass the check valve 188
when the hydraulic pressure in the conduit 180 exceeds the safety
threshold set by the relief valve 190.
The inventive anti-spin mechanism 28 exhibits many advantages over
previously known anti-spin mechanisms.
For instance, it reacts immediately to a tendency of the main shaft
30 to spin and hence prevents the main shaft 30 from spinning rather
than braking a rotating main shaft. Inertial loads on the hydraulic
brake 62 and the main shaft 30 are therefore reduced. In fact, test
data indicates that only about 180-200 psi of hydraulic pressure
is generated during braking. This pressure correlates to about 3000
inch pounds of holding force and is drastically lower than had been
anticipated prior to testing. However, by permitting main shaft
rotation in the spinning direction under some circumstances such
as tramp relief, the anti-spin mechanism 28 reduces manganese wear,
reduces shock loads on the crusher 10 and prevents stones from
being thrown from the crusher.
In addition, the anti-spin mechanism 28 is usable with a solid
or nearly solid one-piece main shaft 30 because it cooperates only
with the lower portion of the main shaft 30. It is also easily accessible
for repair or replacement because it is located beneath all major
components of the crusher 10. This accessibility facilitates both
new and retrofit installation and also facilitates replacement.
Moreover, because it is relatively compact and can be used with
a main shaft of standard length, the anti-spin mechanism does not
unnecessarily increase the overall height of the crusher 10.
Other advantages of the invention, as well as many changes and
modifications which could be made thereto without departing from
the spirit thereof, will become apparent from the appended claims.
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