Abstrict A tapered bushing for use in connection with a shaft for a rock
crusher. The bushing tapers inwardly from top to bottom and the
thickness of the bushing also tapers evenly from a first maximum
predetermined thickness to a second minimum predetermined thickness.
Claims What is claimed is:
1. A bushing for use in a conical rock crusher, said rock crusher
including a generally concave crushing bowl and a crusher head including
a mantle mounted on the outside of the crusher head, said mantle
interacting with said crushing bowl for crushing rocks, said crusher
head being assembled onto a shaft, said bushing providing an abutting
supporting surface coextensive with the length of the exterior surface
of said shaft, said shaft having a central longitudinal axis extending
the length of said shaft, said bushing comprising: an upper end
including a first diameter being laterally spaced apart from an
upper end of said shaft; a lower end including a second diameter
being laterally spaced apart from a lower end of said shaft, said
second inner diameter being less than that of said first inner diameter;
said bushing being evenly tapered from said upper end to said lower
end; said upper end having a first outer diameter; said lower end
having a second outer diameter being less than that of said first
outer diameter, said first and second outer diameters being eccentric
of said first and second inner diameters, respectively.
2. The bushing according to claim 1 wherein said longitudinal
axes of said first and second outer diameters are coextensive.
3. A bushing for a gyrating shaft, said bushing comprising: a generally
cylindrical body, said body having a thickness evenly varying in
size from a predetermined maximum thickness to a predetermined minimum
thickness.
4. The bushing according to claim 3 wherein said body further comprises:
an upper end, said upper end having a first inner diameter; and
a lower end having a second inner diameter, said second inner diameter
being less than said first inner diameter, said body being evenly
tapered from said upper end to said lower end.
5. The bushing according to claim 4 wherein said bushing and said
shaft are in linear contact along the length of said shaft when
said shaft is gyrating.
Description BACKGROUND OF THE INVENTION
[0001] The present invention relates to rock crushers and to improved
bushings used in connection with the rock crushers.
[0002] Crushing stones and rocks requires rugged and sturdy equipment
that can stand up to the harsh environment and heavy loads of rock
crushing.
[0003] In conical rock crushers, a shaft and head assembly gyrates
to crush rocks. The gyrating motion is imparted to the shaft through
a bushing. The shaft bears on one side of the bushing during the
rock crushing load. However the shaft tends to rub and burn the
bushing on the opposite side, especially when the rock crusher is
running without a load, such as before starting or after stopping
the rock crushing process. Prior art designs provide uneven and
point contact between the bushing surface and the shaft, which contributes
to the burning of the bushing. Thus, an improved bushing is desired.
SUMMARY OF THE INVENTION
[0004] The present invention provides an improved bushing for use
in a rock crusher. Within the rock crusher sits a crusher head and
a shaft assembly. The assembly rotates or gyrates, which allows
a mantle located on the exterior of the crusher head to come in
contact with the rock crusher bowl for crushing rocks. As the shaft
gyrates, especially without rocks within the crusher bowl, the shaft
comes in contact with the bushing, which acts as an abutting surface
for the maximum outer movement of the shaft. The bushing is tapered
downwardly, which allows for evenly dispersed contact along the
length of the shaft as it gyrates. Furthermore, the thickness of
the bushing is asymmetrical, with the thickness evenly varying from
a predetermined maximum thickness to a predetermined minimum thickness.
The asymmetrical thickness further provides for an even abutting
surface for the shaft to contact. The result is a shaft load that
is dispersed over a wide area of the bushing, which minimizes burning
of the bushing. In addition, the reduced clearance between the shaft
and the bushing creates better hydrodynamic bearing action, resulting
in enhanced load capabilities for the bushing. Overall, the combination
of the factors improves the reliability of the crusher and the crushing
process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 depicts a side elevational view, partially in section,
of a rock crusher currently used in the art.
[0006] FIG. 2 depicts an enlarged view of a prior art shaft and
bushing.
[0007] FIG. 3 depicts a view, similar to that of FIG. 2 of a shaft
and bushing in accordance with the present invention.
[0008] FIG. 4 depicts an overhead view of the shaft and improved
bushing in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0009] Although the disclosure hereof is detailed and exact to
enable those skilled in the art to practice the invention, the physical
embodiments herein disclosed merely exemplify the invention which
may be embodied in other specific structure. While the preferred
embodiment has been described, the details may be changed without
departing from the invention, which is defined by the claims.
[0010] FIG. 1 depicts a side elevational view, partially in section,
of a rock crusher 10. The crusher 10 is shown without any rocks
within the assembly, that is, the rock crusher is being shown operating
without a crushing load. The crusher 10 comprises a supporting base
12 that supports a stationary frame 14. The frame 14 provides a
generally concave crushing bowl or container 16. Within the crushing
bowl 16 resides a crusher head 18. Mounted on the outside of the
crusher head 18 is a mantle 20 which interacts with the inner surface
21 of the crushing bowl 16 to crush the rocks when they enter the
bowl 16. The crusher head 18 is assembled to a shaft 22 which gyrates
about the main axis of the crusher to allow the crusher head 18
to crush rocks against the sides of the bowl 16. The shaft 22 is
connected to a drive shaft or other power means 23 that provides
power for the shaft 22 and the crusher head 18 to gyrate or rotate.
A bushing 24 located around the shaft 22 provides means that will
carry the radial load of the crusher 10 during crushing and non-crushing
time intervals. The bushing 24 is the focus of the present invention.
[0011] FIG. 2 shows a shaft 122 and a bushing 124 according to
the prior art. It will be understood that when referring to the
shaft 122 we are referring to the area of the shaft 122 that is
positioned within the bushing 124 and not the entire length of
the shaft 122 which normally will extend further upward into the
center of the crusher head 18. The bushing 124 has a top end 126
and a bottom end 128 and is of a generally cylindrical shape. The
shaft 122 as shown, would be gyrating without a load of rocks in
the container 16 (see FIG. 1). When this happens, the outer limit
of the movement of the shaft 122 is defined by the bushing 124.
The shaft 122 contacts the top end 126 of the bushing 124 when rotating
but does not contact the bottom end 128 of the bushing 124 as is
evident in the drawing. As this occurs, the force and pressure exerted
on the bushing 124 is concentrated at a specific pinch point 129
at the top end 126 of the bushing 124. The bottom end 128 of the
bushing 124 does not make contact with the shaft 122. The concentration
of force at the pinch point 129 of the bushing 124 leads to burning
of the bushing 124 which leads to the failure of the bushing 124
and other adverse effects on the crusher 10.
[0012] FIG. 3 shows a side elevational view of the shaft 22 and
the bushing 24 in accordance with the present invention. As stated
with respect to the prior art, it is to be understood that the shaft
refers to the area of the shaft that contacts the bushing 24 and
not the entire shaft 22. As shown with the prior art in FIG. 2
the shaft 22 is also rotating without a load of rocks in the container
16 as shown in FIG. 1. As disclosed in FIG. 3 the bushing 24 has
a top end 26 and a bottom end 28. The bushing 24 evenly tapers inwardly
from the top end 26 to the bottom end 28 which results in the top
end 26 having a first inner diameter ID.sub.1 larger than that of
a second inner diameter ID.sub.2 located at the bottom end of the
bushing 24. The arrangement of the bushing 24 allows the shaft 22
to evenly be in contact along the entire length of the bushing 24
and removes the pinch point 129 discussed with respect to the prior
art assembly shown in FIG. 2. The bushing 24 provides an abutment
for the shaft 22 that is coextensive along the length of the shaft
22. Thus, contact between the shaft 22 and the bushing 24 is linearly
displaced along the entire length of the shaft 22 as opposed to
a single point, with the result being substantially less burning
of the bushing 24 and a longer life for the bushing 24. Burning
of the bushing 24 is virtually eliminated according to the present
invention. A longer bushing life equates into less downtime for
a rock crusher previously required to replace worn bushings, which
leads to an increase in productivity.
[0013] Still referring to FIG. 3 the bushing 24 has a first outer
diameter OD.sub.1 located at the top end 26 of the bushing 24 and
a second outer diameter OD.sub.2 located at the bottom end 28 of
the bushing, with the second outer diameter OD.sub.2 being preferably
less than that of the first outer diameter OD.sub.1. The outer diameters
are spaced apart from the inner diameters for illustrative purposes
and to distinguish and clarify what dimension is referred to for
each diameter; the respective inner and outer diameters should be
considered as intersecting the bushing 24 at the same latitude.
The outer diameters and the inner diameters are eccentric of one
another, or are not centered on the same axes. More specifically,
the first inner diameter ID.sub.1 is eccentric of the first outer
diameter OD.sub.1 and the second inner diameter ID.sub.2 is eccentric
of the second outer diameter OD.sub.2. However, the outer diameters
OD.sub.1 and OD.sub.2 may be substantially coextensive along the
same axes.
[0014] Referring further to FIG. 3 the bushing 24 is shown having
a first side 30 and a second side 32. The bushing 24 normally encircles
the shaft 22 but is shown having the first side 30 and the second
side 32 for illustrative purposes. Because of the eccentric diameters
discussed above, the first side 30 has a first thickness T.sub.1
and the second side 32 has a thickness T.sub.2. The thickness T.sub.1
is thicker than the thickness T.sub.2. The overall thickness of
the bushing 24 tapers evenly from the thickness T.sub.1 to the thickness
T.sub.2. The tapered thickness of the bushing also contributes to
the solid contact made between the shaft 22 and the bushing 24
thereby further reducing potential burning of the bushing 24.
[0015] FIG. 4 depicts an overhead view of the shaft 22 and the
bushing 24. As described with respect to FIG. 3 the overall thickness
of the bushing 24 tapers evenly from the greatest thickness T.sub.1
to the narrowest thickness T.sub.2. The thicknesses T.sub.1 and
T.sub.2 do not necessarily need to be located on the right and left
sides of the shaft 22 respectively. Since the bushing 24 is preferably
circular throughout its length, it should be understood that actual
orientation of the thickness T.sub.1 and T.sub.2 will be determined
as to what angle or perspective a person is looking at the shaft
22 and the bushing 24. The maximum thickness of the bushing would
be considered T.sub.1 and the minimum thickness T.sub.2 would be
considered, regardless of what direction or angle the bushing 24
was viewed.
[0016] The inward tapering of the bushing 24 and the tapering of
the thickness do not have to be substantial to result in the desired
effect for the assembly 10. For instance, in many industrial-sized
rock crusher assemblies, the shaft 22 may be about 45 inches in
length. This would be the length below the rock crusher head, and
not include the length of the shaft that may extend inwardly of
the crusher head. The first inner diameter ID.sub.1 may be approximately
about 137/8 inches and the second inner diameter ID.sub.2 may be
approximately about 101/4 inches. The change in the bushing diameter
is around 3 to 31/2 inches, or approximately 1 inch taper in thickness
for every 12 to 15 inches of the length of the shaft. Similarly,
the difference between the thickness T.sub.1 and T.sub.2 of a bushing,
for a shaft of about 45 inches in length, is approximately 130 mils,
or approximately 1/8 of an inch. The slight adjustments are enough
to provide for a more efficient bushing. It should also be understood
that the above values could be adjusted depending on specific needs
or arrangements for a rock crusher. Provided that the varying of
the bushing dimensions conveys an even, abutting surface along the
entire length of the shaft, the values would fall within the scope
of the invention.
[0017] The bushing 24 has been discussed as being evenly tapered.
It may be possible that the outside of the bushing does not evenly
taper, and the bushing would still fall within the scope of the
invention. Also, either the top of the bushing or bottom of the
bushing, where the bushing may not come in contact with the shaft,
may not necessarily be evenly tapered either. Provided that the
surface of the bushing that comes into contact with the surface
of the shaft is evenly tapered so that individual pinch points between
the shaft and the bushing are removed, the bushing would fall within
the scope of the invention.
[0018] The foregoing is considered as illustrative only of the
principles of the invention. Furthermore, since numerous modifications
and changes will readily occur to those skilled in the art, it is
not desired to limit the invention to the exact construction and
operation shown and described. While the preferred embodiment has
been described, the details may be changed without departing from
the invention, which is defined by the claims. |