Conveyors – chutes – skids – guides – and ways – Rollerways – Submerging and rising
Reexamination Certificate
2003-04-04
2004-09-21
Crawford, Gene O. (Department: 3651)
Conveyors, chutes, skids, guides, and ways
Rollerways
Submerging and rising
C193S037000
Reexamination Certificate
active
06793060
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an improved conveyor wheel or roller for use in storage racks, roller conveyors and the like, and more particularly to an improved conveyor wheel having a hardened outer body shell which defines an outer annular tread for engagement with a load such as a pallet, and the manufacturing method for the conveyor wheel.
BACKGROUND OF THE INVENTION
Conveyors and storage racks, and in particular those which have a slight slope so as to provide gravity-urged movement of loads such as pallets and the like, typically employ a large number of roller units which support the load and provide for movement thereof along the conveyor. A fragmentary view of a known storage rack or conveyor unit
11
is illustrated in
FIG. 1
, which unit includes a frame or track
12
on which a series of roller units
13
are supported. The roller unit
13
typically includes a shaft
14
which is supported on the frame and which rollingly supports a conveyor wheel
16
thereon, the latter being disposed so that an upper surface thereof defines a generally tangential plane which provides for supportive engagement with the underside of a load
17
, such as a conventional pallet. An example of such arrangement is illustrated by U.S. Pat. No. 6,435,328, although it will be appreciated that numerous other conventional conveyor or storage rack arrangements employing conveyor wheels are well known, and the improved conveyor wheel of this invention is obviously usable therewith.
The conveyor wheel
16
is widely used in many conveyor applications and, as illustrated in
FIGS. 2-3
, comprises a curled edge conveyor wheel constructed principally of four components for defining the outer load-engaging surface and the outer raceway for the ball bearings. This design evolved many years ago from a design adopted from the roller skate industry with this curled edge conveyor wheel construction, as illustrated by
FIGS. 2-3
, the four principal components which define the shell include two identical stamped steel outer ball raceway washers
21
and
22
which are typically case hardened after stamping, a soft steel outer body shell
23
which serves as the wheel's outer tread and raceway retainer, and a soft steel retainer washer that completes the outer body and assists in retaining the bearing raceway.
The stamped outer ball raceway washers
21
and
22
are identical, one serving as the left hand and the other serving as the right hand component of the outer raceway for confining a plurality of ball bearings
26
, the latter being engaged with an inner bearing race
27
defined on and surrounding a support hub or sleeve
28
, the latter constituting the inner bearing race member. The outer shells or parts
23
and
24
are assembled over the bearing raceway washers
21
-
22
and are thereafter die struck so as to curl the outer edge of outer body shell
23
over the outer edge of retainer washer
24
, whereby the soft outer shell
23
thus holds the entire wheel arrangement together.
Considering the above construction in more detail, the outer body shell
23
and retainer washer
24
have respective arcuate annular inner rims
31
and
32
which cooperate to define the outer bearing race for confining the ball bearings
26
, and the arcuate inner rims
31
-
32
respectively join to annular walls
33
-
34
which project radially outwardly, which walls
33
-
34
at their radially outward ends flare outwardly away from one another. The radial wall
33
of the outer body shell
23
in turn joins to an annular outer wall
36
which extends transversely throughout the width of the conveyor wheel and hence defines a tread which is of a generally cylindrical configuration for contact with a load. The outer free edge of the outer wall
36
is then suitably stamped by being deformed radially inwardly so that there is defined the curled edge
37
which wraps around the outer annular edge of the retainer washer
24
to hence maintain the overall housing structure in a fully assembled and confined condition.
Because the outer body shell
23
must be stamped and deformed during assembly so as to create the curled flange
37
which retains the housing in an assembled condition, the outer shell
23
and in particular the outer tread
36
thereof must necessarily be of a soft steel in order to permit the die forming thereof during assembly. Furthermore, once the wheel housing is assembled with the bearing balls
26
contained therein, subsequent hardening can not be feasibly carried out since such hardening would damage the already hardened balls
26
and ball raceway washers
21
-
22
.
The conveyor wheel
16
as described above, even though it has been and continues to be used in many conveyor applications, possesses design characteristics that have been observed to contribute to early failure and high cost. For example, it has been observed that a conveyor wheel in accordance with this design does not have a long life cycle when utilized in use applications involving heavy loading, impact loading and/or intrusion by nails protruding from the bottom boards of wooden pallets that are being conveyed over their surface. The soft steel of the outer housing shell
23
has been observed to collapse, causing the outer ball raceways
21
-
22
to spread apart, thereby allowing the ball bearings to fall out of the assembly and resulting in complete bearing failure as well as failure of the conveyor system.
In situations in which there is a need to provide a conveyor wheel having a hardened outer body shell, attempts have been made to use a conveyor wheel of the type illustrated by FIG.
4
. The known conveyor wheel
41
of
FIG. 4
is defined principally by two stamped and hardened wheel shells
42
which are normally of identical construction and disposed and secured back-to-back. The wheel shells
42
define inner arcuate rims
43
which define an outer bearing race for the ball bearings
26
, and these inner rims
43
join to surrounding and radially outwardly projecting annular walls
44
which, during assembly, substantially abut and are fixedly secured in a conventional manner, such as by rivets
46
. The radial walls
44
at their outer edges are appropriately deformed through substantially 90° corners to define transversely projecting outer flanges
47
which, when the two wheel shell members
42
are assembled, project axially in opposite directions so that these flanges
47
hence define the outer load-engaging tread of the conveyor wheel. With this construction, however, the load contact area defined by the outer wheel tread (as defined by the pair of flanges
47
) is of reduced contact area due to the annular groove
48
which necessarily occurs due to the manner in which the flanges
47
are formed. This groove
48
hence effects a significant reduction in the load-bearing contact area defined by the wheel. Still further, the flanges
47
normally terminate in free edges
49
which are sharp, particularly at the corners thereof, and it has been observed that these sharp edges
49
can cut into and severely damage the load which is engaged with the conveyor wheels, particularly when the load tends to be displaced transversely relative to the conveyor wheels. Also, these edges can hang-up on the loads and prevent the loads from being sidewardly displaced. Accordingly, while wheels of the type illustrated by
FIG. 4
have been utilized in an attempt to provide a hardened annular tread, they nevertheless have not proven totally satisfactory in all applications, particularly those involving side movement or side transfer of the loads.
There thus remains a need in the conveyor industry to provide a conveyor roller/wheel having an outer body shell with an appearance and surface similar to that provided by the traditional roller of
FIGS. 2-3
, but having a hardened outer body shell which provides a significant annular tread for defining a wide contact area, but which is capable of providing wear and durability, such as when handling impact loads or loads where pallets have protruding nail
Crawford Gene O.
Flynn ,Thiel, Boutell & Tanis, P.C.
L.B. International, Inc.
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