Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED MATERIAL HANDLING CONVEYOR
This invention relates generally to material
handling conveyors, and more particularly to such
conveyors which utilize a plurality of clusters with
5freely rotatable rollers affixed to selectively
powered shafts.
Friction is an important factor in the
performance of any material handling conveyor, but is
especially important in those conveyors that employ
10 multiple clusters attached to shafts with each cluster
having a number of free rotatable barrell-shaped
rollers arranged around the periphery of the cluster
with the axis of rotation for the rollers set at an
angle to the axis of the shaft to which the cluster is
15 attached, such as conveyors of the type disclosed and
claimed in U.S- patent application Serial Number
06/781,443, filed September 27, 1985. Such conveyors
are capable of rotating any flat-bottomed object about
a vertical axis or in any direction by selectively
20 controlling the direction of rotation of the shafts on
which the clusters are attached. The motion of the
object is determined by the summation of the friction
forces (magnitude and direction) exerted by the
rollers on the flat-bottom. Friction forces should,
25 and ideally do, act in a direction which is parallel
to the axis of the shaft on which the roller is
mounted. Friction forces which act perpendicular to
this shaft axis detract from the efficiency and
responsiveness of the conveyor. It is also important
30 that such detrimental forces be substantially the same
whether wet or dry.
The present invention provides a cluster for
a material handling conveyor which functions
substantially the same whether it is wet or dry, which
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provides low frictional forces relative to rotation of
the rollers about their axes, which is relatively
inexpensive to manufacture and maintain, which may
readily be retrofitted to existing conveyors, and which has
relatively high reliability and responsiveness.
In accordance with an aspect of the invention a
cluster for use in a material handling conveyor having a
number of driven shafts comprising:
a body member for non-rotational mounting on one
of said driven shafts;
a plurality of rollers, each of which has a central
bore;
a pair of legs formed on said body member for mounting
each roller on the periphery of said body member;
a pair of bushings, one bushing being pressed into and
recessed below each end of the central bore of each
roller;
a roller shaft made of a material which will not
oxidize and which has a low coefficent of friction
with respect to said bushings, extending through each
of said pair of legs and said bushings of each roller
at an angle to said driven shaft and retained in said
pair of legs; and
a washer interposed on said roller shaft at each end
of the roller, each washer being incapable of engaging
the bushing and engageable directly by, but
independently rotatable relative to the roller and
being formed of a hard material having a low
coefficient of friction with respect to the roller.
These and other objects of aspects of the present
invention will become more readily apparent from a perusal
of the following detailed description and the accompanied
drawings, wherein:
Figure l is a plan view of shaft used in a material
handling conveyor incorporating the present invention;
Figure 2 is a plan view of one of the clusters shown
in Figure l;
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Figure 3 is an expanded view illustrating the mounting
of one of the rollers of the cluster shown in
figure 2;
Figure 4 is a longitudinal cross-section
of the roller and a portion of the cluster shown in
Figure 3; and
Figure 5 is a detailed sectional view of
the connection of the roller shaft to the cluster.
Referring now to Figure 1, there is shown one shaft
10 of the plurality of shafts arranged on a frame and
selectively driven by a chain trained over the, sprocket
12 and a sprocket affixed to and driven by a reversible
motor, as shown and described in the aforementioned patent
application. A plurality of clusters 14 are affixed to
the shaft 10 for rotation therewith. As shown best in
Figure 2, a plurality of rollers 16 are arranged around
the periphery of the body 18 of the cluster 14 and set at
an angle of about 45 degrees relative to the axis 20 of
the cluster 14. The rollers 16, are shaped to essentially
define the surface of the central portion of a sphere and
comprises the surfaces contacting the flat-bottomed
object.
Referring to Figure 3, the roller 16 is mounted for
rotation on a shaft 22 which extends between a pair of
outward-extending legs 24 and 26 formed on the body 18.
The shaft 22 is retained in this position and restrained
from rotation by a flat 28, formed on one end of the shaft
22, which end terminates in a reduced diameter threaded
portion 25. The leg 26 has a D-shaped hole 30, as best
seen in Figure 5, which intersects with a bore 32 is
slightly larger than the major diameter of the shaft 22,
as is an aligned bore 34, formed in the opposite leg 24.
To assemble, the threaded end of the shaft 22 is inserted
through the hole 34, the roller 16 and the hole 32 with
the flat 28, engaging the D-shaped hole 30. A locking nut
40 engages the threaded end 25, to hold the assembly in
place.
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Flat washers 50 and 52 are positioned on the shaft
22, between the ends of the roller 16 and the inner side
of the legs 24 and 26 respectively. These washers 50 and
52 are made of a hard material of the ends of the roller
16, which may be made of am aluminum alloy. A suitable
material for these washers 50 and 52 is molybdenum filled
nylon. The end surfaces 27 of the roller 16 function as
the bearing surfaces for washers 50 and 52; the relative
rotation being between the rotating roller and the
stationary washers. As shown in figure, bushings 54 and
56 are pressed into a central bore 58 formed in the roller
16. the shaft is preferably polished and made of a
material which will not oxidize, such as stainless steel,
so that water will not adversely affect performance of the
roller. The bushings 54 and 56, therefore, must be
composed of a material compatible with the shaft 22 and
also possess a low coefficient of friction. A brushing
that has been found to operate with superior results is a
mild steel coated with a porous bronze which has been
impregnated with polytetrafluoroethylene and lead. The
combination of flat nylon washers at the ends of the
roller 16 and the aforementioned bushings in the roller
bore 58 to engage the stainless steel shaft 22 have
produced superior results in both wet and dry conditions.
While one embodiment of the present invention has
been shown and described herein, it will be appreciated
that various changes may be made therein without departing
from the spirit of the invention as defined by the scope
of the appended claims.
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