Abstrict A crusher for reducing the size of pieces of rock, concrete and
the like is disclosed. A pair of resonant beams are suspended at
their upper nodes from the upper end of a frame. The beams are driven
by an oscillatory driver which engages the beams near their anti-nodes.
A pair of opposed jaws are mounted at the lower ends of the beams
and their mutual, reciprocal action applies compressive forces to
material fed therebetween which causes the material to break apart.
The jaws may be moved apart by a pair of hydraulic cylinders to
allow adjustment of the material size discharged from the crusher.
The hydraulic system actuating the cylinders is especially adapted
to absorb shock imparted by the reactive forces of the jaws against
the material being crushed.
Claims What is claimed is:
1. An apparatus for crushing large masses, the apparatus comprising:
a supporting frame;
a pair of resonant beams with similar resonant characteristics
having anti-nodes at each end and nodes spaced inward from the ends,
said beams being suspended from the frame at a location on each
beam substantially coincident with the node proximate the upper
end of the beam;
means for inducing a standing lateral wave in each of the beams
at or near the resonant frequency of the beams so that the lower
ends of the beams move toward and away from each other in a synchronous
manner;
means mounted on the lower ends of the beams for striking the masses
as they are fed to the apparatus and for imparting opposed compressive
forces to the masses which result in the masses being crushed;
means for engaging the beams at the nodes proximate their lower
ends to bias said beams toward one another at said lower nodes to
counteract the reaction forces of the beams striking the masses.
2. An apparatus as in claim 1 wherein the means for inducing a
lateral wave is attached to the upper end of both beams.
3. An apparatus as in claim 1 wherein the means for inducing a
lateral wave includes:
a motor;
a first shaft operatively connected to the motor and received within
the upper end of the first resonant beam;
a second shaft operatively connected to the motor and received
within the upper end of the second resonant beam; and
one or more eccentric weights mounted on each of the first and
second shafts.
4. An apparatus as in claim 1 wherein the means for striking the
masses and for applying compressive forces comprises a pair of opposed
faces defining a cavity of decreasing width in the downward direction,
the faces being operatively connected to the resonant beams and
having means for penetrating the masses to initiate fissures in
the masses as the compressive forces are applied by the resonant
beams.
5. An apparatus for crushing solid material, the apparatus comprising:
a frame;
a first beam being composed of a solid homogenous material and
having dimensions which impart a pre-determined resonant characteristic;
a second beam having dimensional and resonant characteristics substantially
the same as the first beam;
means for suspending the first and second beams from the frame;
an oscillatory driver mounted on the beams to induce standing lateral
waves in said beams which are mirror images of one another, the
waves having an upper and a lower node and an upper, a middle and
a lower anti-node;
a pair of jaws having inclined surfaces and mounted at the lower
ends of the respective beams so that the jaws will oscillate therewith,
the opposed inclined surfaces on the jaws defining a cavity with
a large opening at the top for receiving the solid material and
a narrow opening at the bottom for discharging the material after
it has been crushed by the jaws; and
means for spacing the jaws apart in the direction of their oscillation,
the means for spacing being adjustable so that the size of material
discharged through the narrow opening can be adjusted.
6. An apparatus as in claim 5 wherein the oscillatory driver includes:
a motor;
a first shaft extending through the upper end of the first beam
along a line substantially coincident with the upper anti-node and
having one or more eccentric weights secured thereto;
a second shaft extending through the upper end of the second beam
along a line substantially coincident with the upper anti-node and
having one or more eccentric weights secured thereto; and
means for operably connecting the motor to both the first and second
shafts.
7. An apparatus as in claim 5 wherein the means for spacing the
jaws apart engages each beam substantially at the lower node thereof
and biases the beams toward one another to counteract the reaction
forces of the jaws striking the solid material.
8. An apparatus as in claim 5 wherein the means for spacing the
jaws apart includes:
a means for encompassing the first beam slidably mounted on the
frame;
a means for encompassing the second beam slidably mounted on the
frame; and
a means for moving the first encompassing means relative to the
second encompassing means while allowing both encompassing means
to slide relative to the frame.
9. An apparatus as in claim 8 wherein the means for moving comprises
at least one hydraulic cylinder, a means for providing hydraulic
fluid to the cylinder, and a means for absorbing shocks operably
connected to the means for providing hydraulic fluid.
Description BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to crushers for rocks,
ores, and the like, and more particularly to a crusher having opposed
crushing jaws which are driven by resonantly-excited beams.
2. Description of the Prior Art
Crushing raw materials to reduce them to a smaller size is a process
basic to many industries. Such crushing typically takes place in
several stages with large pieces of, for example, mineral ore being
fed first to a jaw-type crusher which breaks the ore down into pieces
which are several inches across. Such crushers typically include
a reciprocable jaw adjacent a fixed wall. Either the surface of
the jaw, the wall, or both, is inclined so that the jaw and the
wall define a chamber having a decreasing width in the downward
direction. By feeding the ore to the chamber and by driving the
jaw periodically inward against the wall, the ore is broken down
into successively smaller pieces as it moves downward. Once the
ore has been broken into pieces corresponding to the maximum distance
between the lower ends of the jaw and the wall, it falls to a receptacle
or conveyer for further processing. Crushers of this type normally
operate continuously with the larger pieces being fed on top urging
those pieces below downward so that they will be crushed.
Upon discharge from the jaw-type crusher, the ore may be fed to
a cone crusher for further size reduction. The cone crusher discharges
material a fraction of an inch across. This material may then be
fed to a ball (or rod) mill to produce a fine, particulate material
in a broad range of mesh sizes.
It is thus desirable to provide a jaw-type crusher which would
reduce the material size sufficiently so that additional stages
of crushing would no longer be necessary to produce a broad range
of material sizes.
Typically, jaw-type crushers have been powered by mechanical means
which apply force directly between the jaw and the frame of the
crusher. While such a construction has proven workable, it suffers
from severe maintenance problems resulting from the stress placed
on the frame. It is thus desireable to provide a crusher where the
crushing jaw is powered by means which impart little or no force
to the frame of the crusher.
In order to reduce vibrations, attempts have been made to power
jaw-type crushers using horizontally-mounted beams to drive a pair
of crushing jaws mounted to receive feed material therebetween.
See, for example, U.S. Pat. Nos. 3131878; 3284010; and 3414203.
In each of these, a standing, longitudinal wave is induced in the
beams to cause the jaws to reciprocate relative to each other. In
order to function properly, such machines require very long beams
which greatly increase the cost of constructing the machine. If
the beams are shortened, the crusher operates at high frequency
and low amplitude, characteristics which are not effective in most
crushing operations.
It is known to reciprocally drive devices by placing them at an
anti-node of a member which is vibrating transversely at or near
its resonant frequency. See, for example, U.S. Pat. Nos. 3232669
and 3367716 to Bodine, which disclose the theoretical advantages
in using such resonant systems to apply large forces. It is unknown,
however, to combine such transverse resonant drive means in opposed
relation in a crusher for rocks, ores and the like to achieve the
objects of the present invention as set forth above.
SUMMARY OF THE INVENTION
The present invention is a crusher capable of imparting very large
compressive forces to large pieces of rocks, ores and the like,
with minimum reactive force being experienced by the frame of the
crusher. It accomplishes this by providing a pair of opposed jaws
mounted at the lower anti-nodes of two resonant beams suspended
from their upper nodes on the frame. By exciting the beams synchronously,
but 180.degree. out of phase, the jaws reciprocate inward to pulverize
any object caught therebetween.
Since the resonant beams are supported at their nodes, the oscillatory
forces exciting the beams will not be transmitted to the frame.
Moreover, the reaction force resulting from the impact of each jaw
on the feed material is balanced by an equal but opposite force
experienced by the other jaw since the jaws are driven in an opposed
manner, that is, 180.degree. out of phase. Thus, the only portions
of the crusher which experience stress are horizontal members which
restrain the lower nodes of the beams, both of which experience
a periodic tensile force whenever the jaws engage a rock. Since
the forces are balanced, however, the frame as a whole will experience
little vibration and the problems associated with stress and fatigue
found in the prior art crushers are avoided.
An additional advantage of the present invention results from the
efficient transfer of energy resulting from the use of a resonant
system. Since a greater percent of the input energy is transferred
to the material being broken, the material can be broken into smaller
pieces than by conventional means and the need for further processing
in a cone crusher and a ball mill may be reduced or eliminated entirely.
In the preferred embodiment, a pair of substantially similar resonant
beams are mounted at their upper nodes from the upper end of an
elongate vertical frame. A pair of oscillatory drivers, typically
mounted at the upper end of each resonant beam at a point coincident
with the beam's anti-node, are driven synchronously, but 180.degree.
out of phase, to induce a standing lateral wave in the beam. The
jaws, which are mounted at the lower ends of the beams at or near
the anti-nodes, are thus able to apply successive compressive forces
to the material fed in from above. Means for restraining the outward
movement of the beams is provided to prevent the beams from moving
apart as the jaws engage the feed material. Such means will typically
comprise a pair of back-up bars disposed adjacent the outer face
of each beam substantially at the lower-node thereof. By connecting
the back-up bars with two hydraulic cylinders, the restraining means
is able to adjust the distance between the jaws to vary the size
of the material discharged therefrom. Additionally, the hydraulic
system for the cylinders may be adapted to absorb shock created
by the impact of the jaws on the feed material.
The use of transversely-excited resonant beams instead of longitudinally-excited
beams, as in the prior art, allows the crushing jaws to be driven
at a frequency and with an amplitude which provides efficient crushing.
Moreover, the resulting machine is more compact than that of the
prior art, resulting in substantial savings in construction costs.
The novel features which are characteristic of the invention, as
to organization and method of operation together with further objects
and advantages thereof will be better understood from the following
description considered in connection with the accompanying drawings
in which a preferred embodiment of the invention is illustrated
by way of example. It is to be expressly understood, however, that
the drawings are for the purpose of illustration and description
only and are not intended as a definition of the limits of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the crusher of the present invention.
FIG. 2 is a front elevational view of the crusher with portions
being broken away.
FIG. 3 is a transverse sectional view of the crusher taken along
line 3--3 of FIG. 2.
FIG. 4 is a detailed sectional view of the lower portion of the
crusher taken along line 4--4 of FIG. 3.
FIGS. 5A and 5B are schematic views of the resonant beams illustrating
the movement induced by the oscillatory driver.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 and 2 the crusher 10 of the present invention
includes a frame 12 a pair of resonant beams 14 15 suspended
from the upper end of the frame, an oscillatory driver 18 for exciting
the resonant beams, and a pair of opposed jaws 20 21 (FIGS. 3 and
4), one attached at the lower end of each resonant beam. The frame
12 includes a base plate 24 having a large opening 26 (FIG. 4) therethrough
for discharging crushed material, four vertical posts 28 projecting
upward from the base plate 24 a horizontal frame 30 mounted at
the top of the posts 28 and adapted to support the oscillatory driver
18 as described in detail hereinafter, and a pair of side plates
32 each having a pair of arcuate slots 34 therethrough. The side
plates 32 are secured at their lower edges to the base plate 24
and spaced apart so that each lies adjacent to a pair of the vertical
posts 28 as illustrated in FIG. 1. The lower ends of the resonant
beams 14 15 and the jaws 20 21 are received into the space between
the side plates 32.
The resonant beams 14 15 are matched heavy steal plates each having
a rectangular cross section with a width equal to the maximum anticipated
dimension of the feed material and a thickness and length chosen
to provide the proper frequency, amplitude and power transmission
characteristics for the system as a whole. The beams 14 15 are
matched in the sense that they resonate at the same frequency, have
the same dimensions and are made from the same material. When resonantly
excited, as described hereinafter, the beams will each have upper
and lower nodes spaced inward from the upper and lower ends respectively,
and anti-nodes located at each end and at the middle. The nodes
are the point of zero lateral displacement while the anti-nodes
are the points of maximum lateral displacement.
The beams are each supported on a shaft 38 extending through the
beam along a line substantially coincident with the upper node.
Each end of the shaft 38 is received in a shock absorbing mount
40 adapted to isolate the resonant beam from the frame. As best
illustrated in FIG. 2 the shock absorbing mounts 40 each include
an inner bearing (not shown) surrounded by resiliant material 42
which is housed within an outer shell 44. A retaining ring 46 secured
at each end holds the shaft 38 in place. The four shock absorbing
mounts 40 are each supported at the upper end of one of the vertical
posts 28 and secured to the frame 30 as well as the associated post.
The oscillatory driver 18 is adapted to impart reciprocating lateral
forces to each of the resonant beams 14 15 so as to induce a standing
lateral wave therein. The lateral forces required may be applied
at either the upper or middle anti-node, although it is more convenient
to mount the driver 18 at the upper ends of the beams as illustrated
herein.
The oscillatory driver 18 includes a motor 50 typically a hydraulic
motor, a gear box 52 which simultaneously rotates a pair of double
universal joints 54 at the same speed but in opposite directions,
and one or more eccentric weights 56 (FIGS. 5A and 5B) which are
mounted on shafts 58 coupled directly to the universal joints 54
and housed in a chamber formed in the upper end of the beams 15
16 beneath a protective covering 60. The operation of the eccentric
weights will be described in detail hereinafter.
The jaws 20 21 are formed from impact and abrasion resistant material
and their particular shape will vary depending on the nature of
the feed material. Referring now particularly to FIGS. 3 and 4
the jaws 20 21 will typically have opposed, inclined faces 64
66 which define a cavity having a wide opening 68 at the top and
tapering to a narrow discharge slot 70 at the bottom. The remaining
two sides of the cavity are defined by side plates 72 74 which
are secured at either side of the jaws 20 21 respectively. The
side plates 72 on jaw 20 terminate at their right end (as viewed
in FIGS. 3 and 4) in a lip 76 adapted to enclose side plates 74
on jaw 21 regardless of the distance between the jaws 20 and 21.
In this way, the cavity remains confined as the jaws 20 21 reciprocate
and material is prevented from dropping out. Alternatively, a stationary
side plate (not shown) may be provided adjacent to the sides of
the jaws 20 21 to define the cavity. The latter approach is less
desirable since abrasion is likely to occur between the moving jaws
20 21 and such a stationary side plate.
The jaws 20 21 may be adapted to intermesh at their lower ends
so that the feed material will be pulverized to a fine mesh. In
this case, the slot 70 will be defined by a plurality of teeth (not
shown) on each jaw which reciprocate inward as the jaws are driven.
As stated hereinbefore, the resonant beams 14 15 are pivotally
supported at their upper ends on shafts 38. Although the resonant
beams 14 15 are not secured to the frame at any other point, a
restraining frame 80 is provided to limit the outward motion of
each resonant beam near its lower end. The restraining frame 80
comprises a pair of back-up bars 82 having rollers 84 at each end
which are received within the slots 34 in the side plates 32 as
best illustrated in FIG. 1. The relative orientation of the rollers
84 and the slots 34 is such that the inward face 86 (that is, the
generally vertical face of the bar 82 disposed toward the center
of the machine) is maintained parallel to the plane of the associated
resonant beam 14 or 15 as the lower end of the beam moves inward
and outward.
A bracket 90 is provided on the interior face 86 of each back-up
bar 82 and completes the enclosure of the associated resonant beam
14 15. A resilient pad 92 is also provided on the interior face
86 of the back-up bar and acts to absorb reactive forces generated
as the jaw impacts against the feed material.
The back-up bars 82 are connected by a pair of hydraulic cylinders
88 which may be adjusted to vary the distance between the jaws 20
21 as required by the particular application. The cylinders 88 may
also be used to move apart the jaws 20 21 to clear material which
becomes jammed therebetween. Each cylinder 88 is connected by a
pair of flexible hoses 96 97 (FIG. 3) to a hydraulic system, not
shown. The hoses 96 97 are connected to either side of a piston
98 within the cylinder 88 and pressure applied to line 97 causes
the cylinder to open, while pressure applied to line 96 causes the
cylinder to close.
In addition to providing the operative means for opening and closing
the jaws 20 21 the hydraulic system is provided with accumulators
100 101 (FIG. 3) to aid in absorbing the reactive forces generated
when the jaws are in operation. The accumulators 100 101 are each
provided with internal air-filled bladders 102 103 to absorb forces
which are transmitted to the cylinders 88 and thus to the hydraulic
system. Since the reactive forces will normally be directed outward,
the force will act to draw the piston 98 outward, or to the right
as viewed in FIG. 3. Thus, the accumulator 100 will normally be
sized larger to absorb a major portion of the reactive forces.
Referring now to FIGS. 5A and 5B, the resonant characteristics
of the beams 14 15 will be explained. The beams 14 15 depend vertically
from the shafts 38 and are otherwise unsupported. The shaft 58 is
journaled through the upper end of each beam 14 15 and has one
or more eccentric weights 56 mounted thereon, as described hereinbefore.
The weights are driven synchronously, but 180.degree. out of phase
by the oscillatory driver 18 as illustrated in both FIGS. 5A and
5B, and each weight exerts an outward centrifugal force as it rotates.
Referring particularly to FIG. 5A, the weight 56 at the top of
beam 14 would be exerting a lateral force in the direction of arrow
110 while the weight 56 at the top of beam 15 would be exerting
force in the opposite direction, as indicated by arrow 112. While
the weights may be driven in either direction, for the purposes
of illustration the weight 56 on beam 14 is shown to rotate counterclockwise
as indicated by arrow 114 while the weight at the top of beam 15
is shown to rotate clockwise, as indicated by arrow 116. Thus, FIG.
5A illustrates the weights 56 at the moment they are exerting the
maximum outward lateral forces on the beams 14 15. The maximum
lateral displacement at the upper anti-nodes will follow a short
time later due to the inertia of the beams. In FIG. 5B, the weights
56 at the top of beams 14 15 are illustrated at the moment they
are exerting their maximum inward force on the beams. Again, the
maximum inward displacement of the upper anti-nodes will occur a
short time after the maximum force has been imparted.
As the inward and outward forces applied to the upper anti-nodes
of the beams 14 15 alternate, a lateral standing wave is induced
in the beam. In FIG. 5A, as the upper anti-node of each beam is
moving outward, the middle anti-node is moving inward as illustrated
by arrows 120. Similarly, the lower anti-nodes are moving outward
as illustrated by arrows 122. The upper node (coincident with shaft
38) and the lower node at 123 of course, remain substantially stationary.
Referring now to FIG. 5B, as the upper anti-nodes move inward, as
indicated by arrows 124 the middle anti-nodes move outward (arrows
126) and the lower anti-nodes move inward (arrows 128). This `S`-shaped
wave pattern is repeated at the frequency induced by the oscillatory
driver 18. Typically, the system will be driven at a frequency slightly
below the resonant frequency to avoid overdriving the system.
In operation, the material to be crushed, typically rocks, mineral
ore, concrete and the like, is continuously fed to the crusher 10
by a conveyer 130 illustrated in FIGS. 1 and 2. As the material
is discharged from the conveyer 130 it falls downward into the
cavity defined by the opposed faces 64 66 of the crushing jaws
20 21 which are driven by the oscillatory driver 18 in the above-described
manner. The opposed faces 64 66 of the jaws 20 21 are provided
with studs 132 (as illustrated in FIGS. 3 and 4) which bite into
the feed material to help break the material apart as well as prevent
said material from being pushed upward. As the jaws constrict about
the feed material, the compressive forces transmitted cause fissures
within the material and eventually cause the material to break into
smaller pieces. As the jaws reciprocate, the smaller pieces fall
further down to a point where the opposed faces 64 66 are closer
together. The process of cracking the material is repeated as the
material falls further and further into the cavity until the material
is finally discharged at a size determined by the width of the slot
70. Thus, the size of the material discharged can be selected by
adjusting the spacing of the jaws using the restraining frame 80
as described hereinabove.
While the preferred embodiment of the present invention is illustrated
in detail, it is apparent that modifications and adaptations of
that embodiment will occur to those skilled in the art. However,
it is to be expressly understood that such modifications and adaptations
are within the spirit and scope of the present invention, as set
forth in the following claims.
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