Note: Descriptions are shown in the official language in which they were submitted.
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ROD RETAINING SNAP ROD ~TITH ENLARGED RETAINING RING
CROSS-REFERENCE TO RELATED APPLICATION
The present application claims priority to U.S.
Provisional Patent Application No. 60/489,824 filed July
24, 2003, entitled "Rod Retaining Snap Rod with Enlarged
Retaining Ring," which is incorporated herein by
reference.
FIELD OF INVENTION
The present invention relates to modular conveying
apparatus.
BACKGROUND OF THE INVENTION
Because they do not corrode, are light weight, and
are easy to clean, unlike metal conveyor belts, plastic
conveyor belts are used widely, especially in materials
handling and conveying food products. Modular plastic
conveyor belts axe made up of molded plastic modular
links, or belt modules, that can be arranged side by
side in rows of selectable width. A series of spaced
apart link ends extending from each side of the modules
include aligned apertures to accommodate a pivot rod.
The link ends along one end of a row of modules are
interconnected with link ends of an adjacent row. A
pivot rod journaled in the aligned apertures of the
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side-by-side and end-to-end connected modules forms a
hinge between adjacent rows. Rows of belt modules are
then connected together to form an endless conveyor belt
capable of articulating about a drive sprocket.
The retention of the pivot rod is an important
feature of the modular plastic conveyor belts. Rod
retention can be accomplished by enlarging the heads of
the pivot rode at both ends but such would not allow for
disassembly without destroying the rod head. Headless
rods have been used for easier production and belt
assembly. These type of rods must be blocked at both
ends of the belt during use. In addition headless rods
are often difficult to remove fox disassembly.
One approach to rod retention is to have a head at
one end of a rod and a headless section at the opposite
end. The headed rod is furnished with a rod retaining
ring disposed on the shaft at a distance from the head
portion of the rod. The rod is inserted through the
pivot holes of the module links, which are all exactly
the same diameter. The retaining ring is just a little
bit larger in diameter than the pivot hole of the
outermost link, such that the ring may be forced through
the pivot hole of the outermost link end and is able to
expand behind the link. In this arrangement the rod is
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kept firmly in position by the retaining ring. The
system described above has the drawback that it requires
tight tolerances of the hole diameter of the outermost
link and the retaining ring diameter. In practice,
there is a risk that the rod does not retain well enough
l0 or is retained tightly and cannot be easily
disassembled. In addition, if the retaining ring is a
little too large, it may be sheared off when inserted.
What is needed is a device that makes the above-
described tolerances less critical.
SUMMARY OF THE INVENTION
The present invention meets the above-described
need by providing a snap rod system such that the
retaining ring can be made larger in order to increase
the size of the shoulder which engages behind the link
face. At the same time due to the larger ring diameter
the bore of the outermost link needs to be enlarged
accordingly in order to allow the larger retaining ring
to be moved through the bore. Due to the larger
difference between the retaining ring and the rod
diameter, the tolerance becomes less critical. In one
embodiment, the bore of the outermost link end is
slightly eccentric in such a way that the enlarged
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shoulder of the retaining ring will be clearly
overlapping the link face when assembled. When the belt
is under tension the rod will be firmly forced into this
retaining position, without losing the ability to
transmit the belt pull.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a cross-sectional plan view of the belt
and pivot rod of the present invention with the pivot
rod extending from the end of the belt prior to
installation;
Fig. 2 is a cross-section plan view of the belt and
pivot rod of Fig. 1 during the initial stage of
installation of the pivot rod;
Fig. 3 is a cross-sectional plan view of the belt
and pivot rod during a later stage of installation;
Fig. 4 is a cross-sectional plan view of the belt
and pivot rod of Fig. 1 shown in the installed
configuration;
Fig. 5 is a cross-sectional view of the belt and
pivot rod of an alternate embodiment of the present
invention shown in the installed configuration;
Fig. 6 is an end view of the belt with the pivot
rod removed for clarity;
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Fig. 7 is a cross-sectional view of the belt shown
in Fig. 5 during removal of the pivot rod with a screw
driver; and,
Fig. 8 is a cross-sectional plan view of an
alternate embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
In Figs. 1-4, a modular belt 10 is formed from a
plurality of belt modules as will be evident to those of
ordinary skill in the art. In Fig. 1, the outermost
modules 13, 16 are shown. As will be evident to those
of ordinary skill in the art, the belt 10 may be formed
into varying widths in bricklayed fashion in a direction
perpendicular to the direction of belt travel 34.
Each module 13, 16 has a module body 20 with a
first and second plurality of link ends 22, 25 disposed
in the middle of the module with respect to the outer
edge 12 shown at the top of Figure 1. Each link end 22,
has opposed side walls 23, 24 defining a first
transverse thickness 21. The first transverse thickness
25 21 is connected to the intermediate section 26 of the
module body 20 at a first proximal portion 27. The
transverse thickness extends from the intermediate
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section 26 in a direction of belt travel to a first
distal portion 29.
The link ends 22, 25 include openings 28, 31
disposed transverse to the direction of belt travel 34.
The openings 28 and 31 receive the pivot rod 19 when
adjacent belt modules 13, 16 are intercalated as shown
in the figure.
The pivot rod 19 is typically round and has a
diameter 30 such that the modules 13, 16 are capable of
pivoting relative to each other for articulating about a
sprocket (not shown). The pivot rod 19 has an end
portion 46 with a diameter 47 that is greater than the
diameter 30 of the pivot rod 19. The pivot rod 19 also
includes a retaining ring 60 spaced apart longitudinally
from the end portion 46. The retaining ring 60 has a
diameter Dr that is larger than the diameter of the
pivot rod 19 and may be formed with a chamfered or
beveled edge 63.
Outermost link end 40 of module 16 is disposed
toward the edge 12 of belt 10. The outermost link end
40 has a recessed portion 43 that is capable of
receiving end portion 46 of pivot rod 19. When the
pivot rod 19 is installed in the belt 10 in the
direction indicated by arrow 49, the end portion 46 is
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received in the recessed portion 43 and abuts with the
portion of the link end surrounding aperture 52 as shown
in Fig. 4.
Link end 40 has an opening 52 with a diameter D1
that is approximately equal to or slightly smaller than
the diameter Dr of the ring 60 but is larger than the
diameter D2 of openings 28, 31.
Belt module 13 also has a specially formed
outermost link end 55 having a recessed surface 56.
The central longitudinal axis 65 of aperture 52 is
offset from the central longitudinal axis 67 of openings
28, 31 such that upon insertion, the pivot rod 19 is
bent as shown in Fig. 3. The pivot rod 19 is bent
during insertion such that once the ring 60 clears
aperture 52, the enlarged shoulder 75 overlaps the link
face surrounding aperture 52 as shown in the circled
area 76 in Fig. 4. The axial misalignment between the
apertures 52 and 31 ensures that the ring 60 does not
exit from the aligned modules 13 and 16 after
installation.
Figs. 2-4 illustrate the position of the pivot rod
19 and the modules 13 and 16 during various stages of
the installation of the pivot rod 19. In Fig. 2, the
pivot rod 19 is shown at the maximum insertion point
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prior to bending the body or shaft of the pivot rod 19.
The rod 19 has been inserted in the direction of arrow
49 until the beveled edge 63 of the retaining ring 60
engages with the edge of the opening 52 on the left hand
side of the figure.
Turning to Fig. 3, deflection of the pivot rod 19
to the right side of opening 52 causes the pivot rod 19
to bend such that the retaining ring 60 aligns with the
opening 52. The retaining ring 60 is sized to
frictionally engage with the inside walls of opening 52
during insertion. Accordingly, the retaining ring may
be roughly equal to or slightly larger in diameter Dr
than the inside diameter D1 of opening 52. As shown, the
left hand side of the beveled edge 63 clears the opening
in Fig. 3 so that the retaining ring 60 may be passed
through the opening 52.
In Fig. 4, the pivot rod 19 has been inserted such
that the retaining ring 60 has passed all the way
through opening 52 and has "snapped" back to the left in
the area shown in circle 76. Once the left edge of the
retaining ring 60 clears the end of the opening 52, the
pivot rod 19 returns to its straight configuration. In
this position, the belt modules 13, 16 are intercalated
and locked together by the retaining ring 60.
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Turning to Fig. 5, an alternate embodiment of the
modular belt of the present invention is shown. The
overlapping area 100 located between the outermost link
end 103 on the first belt module 104 and the rod
retaining ring 106 defines the locking behavior of the
snap rod. The offset 107 between the pivot rod center
axis 109 and the-central axis 111 of opening 112 in the
outermost link end 103 for the retaining ring 106 is a
parameter that affects the locking behavior. This
offset 107 can be increased by reducing the diameter D4
of the rod 118 between the head 121 and the retaining
ring 106. The outermost link end 103 has a recessed
portion 122 that receives the head 121. The opening 112
in the outermost link end 103 is larger than the
openings 127 in the plurality of link ends 130.
The second belt module 133 also has an outermost
link end 136 having a recessed portion 139. The
recessed portion 139 in the second belt module 133
receives the retaining ring 106 when the first and
second belt modules 104, 133 are intercalated and
connected by the pivot rod 118. The outermost link end
136 on the second belt module 133 has a pivot rod
opening 140 with a diameter 143 that is approximately
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equal to the diameter of the openings 127 in the first
belt module 104.
In Fig. 6, the offset 107 is shown from an end view
of the intercalated belt modules. The pivot rod axis
109 and the central axis 111 of the opening 112 are
shown.
As shown in Fig. 7, the pivot rod 118 may be
removed by use of a screw driver 200. The screw driver
200 may be inserted under the head 121 of the pivot rod
118 to provide leverage for bending the rod 118 to align
it with the opening 112 in the outermost link end 103 in
the first module 104. Once the retaining ring 106 is
aligned with the opening 112 the pivot rod 118 may be
removed by sliding it outward in the direction indicated
by arrow 203.
Turning to Fig. 8, an alternate embodiment of the
present invention is shown. A belt 300 is formed from
modules 303 and 306. The modules have outer link ends
309, 312. Link end 309 on module 306 has extra width to
accommodate an internal opening 315 for receiving
retaining ring 360 on pivot rod 319. Link end 312 on
module 303 intercalates adjacent to link end 309 as
shown. The link end 309 also includes a recessed
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portion 318 for receiving end portion 346 of pivot rod
319.
Link end 309 also includes an opening 321
having the same diameter as opening 315. Openings 315
and 321 have a diameter Dl that is approximately equal to
or smaller than the diameter Dr of ring 360. The link
end 312 and the link ends disposed toward the middle of
the belt have openings with a Diameter D2 that is
smaller than D1. The longitudinal axis 325 of openings
315 and 321 is offset from the longitudinal axis 330 of
the opening in link end 312 and the openings toward the
middle of the belt module.
Accordingly, during insertion of the pivot rod 319,
the pivot rod 319 has to be bent and once the ring 360
clears the opening 315 it shifts to the left with
respect to Fig. 8 such that shoulder 375 engages the
link surface around opening 315.
The embodiment of Fig. 8 may also be provided with
a pivot rod 118 (Fig. 5) having different diameters
located above and below the retaining ring 106. In the
example shown, the diameter of the rod between the
retaining ring and the head is smaller than the diameter
of the rod between the retaining ring and the second end
of the rod.
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While the invention has been described in
connection with certain embodiments, it is not intended
to limit the scope of the invention to the particular
forms set forth, but, on the contrary, it is intended to
cover such alternatives, modifications, and equivalents
as may be included within the spirit and scope of the
invention as defined by the appended'claims.
