U.S. patent application number 09/185230 was filed with the patent office on 2001-11-22 for rod retention system for modular plastic conveyor belt.
Invention is credited to PALMAER, ERIC K..
Application Number | 20010042677 09/185230 |
Document ID | / |
Family ID | 22680136 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010042677 |
Kind Code |
A1 |
PALMAER, ERIC K. |
November 22, 2001 |
ROD RETENTION SYSTEM FOR MODULAR PLASTIC CONVEYOR BELT
Abstract
Rod retention systems are disclosed for modular plastic conveyor
belts. In one embodiment the connecting rods, which pass through
interdigited link ends of successive modules, each include a
circumferential groove at one location, receiving a retaining clip
at a position between adjacent interdigited link ends, snapped into
position in the groove. The retaining clip provides easy assembly
using existing tools, and a rod can easily be removed from the belt
by applying sharp force on the end of the rod. In a second
embodiment a rod retention system has blocking members at both ends
of each module row, forming edges of the belt. A space about two or
three link ends wide extends laterally from the blocking member to
the first rod-encircling link end inboard of the blocking member;
within the space the module is devoid of link end structure which
would confine the rod from the bottom of the belt. The rod is
forced into a bending configuration for insertion and removal from
the bottom of the belt, and assumes a substantially straightened,
normal configuration after insertion. In another embodiment the
belt has an opening at the location of the blocking structure,
aligned with the series of link end openings, but the rod end is
preformed in a bent configuration. In a further embodiment the rods
each have heads on one end, and the heads reside inboard of the
blocking structure in the assembled belt.
Inventors: |
PALMAER, ERIC K.; (GRANITE
BAY, CA) |
Correspondence
Address: |
THOMAS M FREIBURGER
650 CALIFORNIA STREET 25TH FLOOR
SAN FRANCISCO
CA
94108
|
Family ID: |
22680136 |
Appl. No.: |
09/185230 |
Filed: |
November 3, 1998 |
Current U.S.
Class: |
198/853 ;
29/428 |
Current CPC
Class: |
B65G 2201/02 20130101;
Y10T 29/49826 20150115; B65G 2207/12 20130101; B65G 17/08
20130101 |
Class at
Publication: |
198/853 ;
29/428 |
International
Class: |
B23P 011/00; B65G
017/08 |
Claims
I claim:
1. In a modular plastic conveyor belt formed of a series of module
rows each including one or more belt modules, each module having a
set of first aligned spaced projections extending in a fore
direction and a second set of projections extending in an aft
direction, the projections having transverse openings which receive
a connecting rod and the first projections of one module row being
interdigited with second projections from another module row, the
module rows being secured together by connecting rods passing
transversely through the transverse openings in the projections,
the improvement comprising: each said connecting rod having, at a
location between two of the interdigited projections, a generally
circumferential groove in the surface of the rod defining a smaller
dimension than the outside diameter of the rod, and a generally
C-shaped retaining clip having an internal dimension smaller than
the outside diameter of the retaining rod but large enough to fit
over the rod in said groove, with an open side of the retaining
clip defining an opening smaller than the rod in the groove, the
retaining clip being of a material having a degree of resilience to
facilitate snapping over the rod at the groove when forced thereon
and a tendency to return to its original shape when unstressed, so
that the C-shaped clip is held in the groove of the rod, and the
clip prevents the rod from substantial transverse movement relative
to the belt modules.
2. The apparatus of claim 1, wherein the connecting rod is formed
of plastic material.
3. The apparatus of claim 2, wherein the generally C-shaped
retaining clip is formed of plastic material.
4. The apparatus of claim 3, wherein the generally C-shaped
retaining clip is formed of Delrin.
5. The apparatus of claim 2, wherein the generally C-shaped
retaining clip is formed of metal.
6. The apparatus of claim 1, wherein the generally circumferential
groove in the rod extends around the entire circumference of the
rod.
7. The apparatus of claim 6, wherein the generally C-shaped
retaining clip has an effective inside diameter larger than the
diameter of the circumferential groove so that the retaining clip
is free to rotate in the groove.
8. The apparatus of claim 1, wherein the generally circumferential
groove in the rod has a width greater than that of the generally
C-shaped retaining clip.
9. The apparatus of claim 1, wherein the interdigited modules
between which the clip is positioned include adjacent projections
of reduced profile, defining at the location of the C-shaped
retaining clip, an interprojection spacing wider than other such
spacings to establish a minimum space within which the C-shaped
retaining clip is positioned, avoiding wear due to side-to-side
module forces.
10. The apparatus of claim 1, wherein the modular plastic conveyor
belt comprises a radius conveyor belt adapted to travel around
lateral curves by collapse of the modular rows together around the
insides of curves, and wherein the generally circumferential groove
and the generally C-shaped retaining clip are located on the
connecting rod in such a position as to be inboard from the outer
belt edge by at least two fore projections and two aft
projections.
11. The apparatus of claim 1, wherein the modular plastic conveyor
belt comprises a radius conveyor belt adapted to travel around
lateral curves by collapse of the modular rows together around the
insides of curves, and wherein the generally circumferential groove
in the rod is located to be positioned inboard from the outer belt
edge, spaced from the outer edge at least as far as a third
inter-projection spacing.
12. In a modular plastic conveyor belt formed of a series of module
rows each including one or more belt modules, each module having a
set of first aligned spaced projections extending in a fore
direction and a second set of projections extending in an aft
direction, the projections having transverse openings which receive
a connecting rod and the first projections of one module row being
interdigited with second projections from another module row, the
module rows being secured together by connecting rods passing
transversely through the transverse openings in the projections,
the improvement comprising: clip means engaging the connecting rod,
between the ends of the belt as formed by the assembled modules,
for locking onto the rod between adjacent projections from two
successive modules, and the connecting rod including a recess
engaged by the clip means, preventing any substantial relative
movement between the clip means and the rod.
13. In a modular plastic conveyor belt formed of a series of module
rows each including one or more belt modules, each module having a
set of first aligned spaced projections extending in a fore
direction and a second set of projections extending in an aft
direction, the projections having transverse openings which receive
a connecting rod and the first projections of one module row being
interdigited with second projections from another module row, the
module rows being secured together by connecting rods passing
transversely through the transverse openings in the projections,
the improvement comprising: rod retaining means on each connecting
rod for securing the connecting rod to the modules and preventing
side-to-side movement of the connecting rod, comprising an enlarged
press fit means on each connecting rod, and press fit bore means
that leads to one projection of a belt module, for receiving the
enlarged press fit means of the connecting rod in forced, press
fit, so as to retain the connecting rod in place in the
interconnected modules.
14. The apparatus of claim 13, wherein the connecting rod is
headless.
15. In a modular plastic conveyor belt having a top and a bottom
and of the type made up of a series of connected elongated molded
plastic belt module rows each including one or more belt modules in
the row such that belts of varying selected widths can be made up
from the modules in a staggered, brick-laid pattern, with the belt
module rows connected by rods extending transversely to the width
of the conveyor belt, each row having a series of first spaced
projections generally regularly spaced and extending in one
direction from the row and a series of second spaced projections
generally regularly spaced and extending in an opposite direction
from the row, the first and second projections of serially adjacent
module rows being longitudinally overlapping and juxtaposed when
the modules are connected serially in the conveyor belt by the
connecting rods extending through transverse openings in the
projections, a system of retaining the connecting rods in the belt
and preventing lateral movement of the rods out of the belt,
comprising: the connecting rods being headless and being capable of
bending without damage, the belt having a blocking structure at
each module row, at each of two opposed edges of the belt, the
blocking structure being positioned to prevent lateral movement of
the rod out of the module row, and including a space inboard of the
blocking structure at least at one side of the module row, wherein
the rod is unconfined from the bottom of the belt so as to allow
the rod to be pulled downward from its end in a bending
configuration to extend below the blocking structure to remove the
rod with a tool or to insert the rod, said space being wide enough
to allow the rod to bend sufficiently to be inserted into and
removed from the module row without damage to the rod, whereby the
rod may be removed or inserted by access to only one side of the
belt.
16. The apparatus according to claim 15, wherein each belt module
has a closed, flat upper surface and whereby, when modules are
linked together, the conveyor belt presents a continuous and solid
top surface.
17. The apparatus according to claim 15, wherein the belt modules
are provided with, adjacent to the blocking structure one or both
ends of the module, and extending perpendicular to the transverse
axis of the module, a series of regularly spaced apart projections
each of which comprises a half-ring structure such that the rod is
unconfined at the bottom of the belt, but is cradled on its upper
surface throughout about half its circumference by the half-ring
structure, thereby enabling the rod to inserted or removed from the
generally aligned transverse openings, while providing mechanical
interaction between the rod and the half-ring projections adjacent
to the blocking structure.
18. The apparatus according to claim 15, wherein the space inboard
of the blocking structure is of a width sufficient to allow
insertion or removal of the rod such that the total bending of the
rod does not exceed 45 degrees.
19. The apparatus according to claim 15, wherein the rod is made of
a plastic and has a diameter of between {fraction (1/16)} inch and
one inch.
20. The apparatus according to claim 15, wherein the belt has a
pitch of between about 0.25 inch and 1.0 inch has a width between
about 2 inches and about 60 inches and wherein each rod has a
diameter of between about 1/8 inch and about {fraction (3/16)}
inch.
21. The apparatus of claim 15, wherein said space inboard of the
blocking structure has a width between about {fraction (1/2)} inch
and about 2 inches and wherein each rod has a diameter of between
about 1/8 inch and about 1/4 inch.
22. The apparatus according to claim 15, wherein the module row has
one of said spaces inboard of a blocking structure both ends of the
module row.
23. A method for connecting rows of serially adjacent conveyor belt
plastic modules by connecting rods to form a continuous conveyor
belt, and for retaining connecting rods within the assembled belt
while allowing retraction and replacement of connecting rods
working from only one side of the belt, comprising: providing a
multiplicity of plastic belt modules, each having a series of first
regular link ends spaced apart and extending in a first
longitudinal direction of a belt in which the module is to be
placed, and a series of second regular link ends spaced apart and
extending in an opposite direction longitudinal to the belt, with
integral, transverse connecting structure secured to the first
regular link ends and the second regular link ends, each of the
spaced apart link ends having a transverse opening to receive a
connecting rod for securing successive modules in a belt, including
edge modules for forming an edge of the conveyor belt, the edge
modules having at least at one transverse end a blocking structure
at the edge of the module and generally in the position which would
be occupied by a regular link end, the blocking structure being
aligned with the apertures of the regular link ends and being
closed so as to block any lateral movement of a rod which resides
in the apertures of the regular link ends, and a space in board of
the blocking structure which is devoid of said regular link ends
and which lacks any link end structure which would confine a rod
from the bottom of the belt, assembling rows of modules to form a
conveyor belt, with at least one module in each module row, and
with an edge module with said blocking structure and space at least
at one side of each row and with a blocking structure at the
opposition end of each row positioned to block exit of a connecting
rod, interdigiting each row of modules with a succeeding row such
that first regular link ends of a row are juxtaposed and
interdigited with second regular link ends of a succeeding row, at
each junction between rows, inserting a first end of a plastic
connecting rod, held at an oblique angle, into the apertures of
link ends adjacent to said space, from the bottom side of the
conveyor belt and from one side of the conveyor belt, and bending
the rod to feed the rod clear of and below the blocking structure,
and continuing to feed the rod through successive link end
apertures with a progressing bend in the rod in an area generally
defined by said space, until the second end of the rod passes over
the blocking structure such that the connecting rod is fully
inserted into the belt, between the two blocking structures at
opposed ends of the belt, then allowing the rod to assume
essentially its original unbent shape, and thus retaining the
connecting rod in place in the belt by the blocking structures at
each end.
24. The method of claim 23, further including a step of removing
the plastic connecting rod from the conveyor belt, comprising
gripping said second end of the connecting rod with a tool from the
bottom side of the belt, where the rod resides within said space
unconfined from the bottom of the belt, then bending the end of the
rod downwardly relative to the line of link end apertures within
which the rod resides until the end of the rod is oriented
downwardly at a sufficient angle to clear the blocking structure at
the edge of the belt; then, with the rod held in such bent
configuration, pulling the rod out from the belt generally at such
oblique angle until the first end of the belt is freed of the link
ends.
25. The method of claim 23, wherein the edge module includes, at
said space between the regular link ends and the blocking
structure, at least one link end comprising a half-ring link end
structure such that the rod is unconfined at the bottom of the
belt, but is engaged on its upper surface throughout about half its
circumference by the half-ring link end structure, thus providing
mechanical interaction between the rod and the at least one
half-ring link end in the absence of regular link ends in said
space.
26. In a modular plastic conveyor belt comprising a plurality of
modules pivotally connected end-to-end by means of connecting rods
extending axially through apertures in interdigited link ends which
extend in forward and rearward directions on each module, an
improved system for retaining the connecting rods within the belt,
comprising: first module edge structure at one edge of the belt,
with a solid blocking device aligned with the apertures in the link
ends and preventing axial movement of the connecting rod out from
said one edge of the belt, second module edge structure on a module
at an opposite edge of the belt, with an aperture in the second
module edge structure generally aligned with apertures in the link
ends, a space adjacent to and inboard of said second module edge
structure, devoid of said link ends with apertures and within which
the end of the connecting rod is relatively unconfined in
directions perpendicular to the length of the rod, and each
connecting rod having a preformed bend near its end which is
adjacent to said second belt edge structure, the preformed bend
being of such angle and length as to place the end of the rod
offset from the opening in the second module edge structure when
the rod is fully assembled in the belt and as to require the end of
the rod to be forced through the aperture on assembly to force the
bend closer to a straight configuration as the rod end passes
through the aperture.
27. In a modular plastic conveyor belt comprising a plurality of
modules pivotally connected end-to-end by means of connecting rods
extending axially through apertures in interdigited link ends which
extend in forward and rearward directions on each module, an
improved system for retaining the connecting rods within the belt,
comprising: the belt having a first edge comprised of module edges
having edge structures with edge openings generally aligned with
the apertures of said link ends, the connecting rods each having a
rod head at an end of the rod adjacent to said first edge, and the
rods being headless at an opposite edge, the rods being capable of
bending without damage, and including a space inboard of said edge
structure at the first edge of the belt, wherein the connecting rod
is unconfined from the bottom of the belt so as to allow the rod to
be pulled downward from its headed end in a bending configuration
to extend below the edge structure to remove the rod with a tool or
to insert the rod, said space being wide enough to allow the rod to
bend sufficiently to be inserted into and removed from the belt
without damage to the rod, whereby the rod may be removed or
inserted by access to only one side of the belt, and whereby the
rod head of the assembled rod is positioned just inboard of said
edge structure, the head being larger than said edge opening such
that the rod is confined within the belt.
28. The apparatus of claim 27, wherein the belt modules include an
upward recess adjacent to and inboard of said edge structure,
positioned to receive a portion of the connecting rod head so as to
cradle the rod head adjacent to the edge structure.
Description
BACKGROUND OF THE INVENTION
[0001] The invention is concerned with modular plastic conveyor
belts, and in particular relates to retention of connecting rods in
such belts.
[0002] Examples of modular plastic conveyor belts are shown in U.S.
Pat. Nos. 4,742,907, 4,901,844, 5,069,330, 5,181,601 and 5,224,583.
The conveyor belts are shown formed of plastic modules having sets
of link ends or projections extending in fore and aft directions,
for interdigiting with similar preceding and succeeding modules.
The interdigited projections have transverse openings through which
pass connecting rods, typically also of plastic. Each module row
includes one or more modules side by side, and the belts can be
made up in virtually any length and width, within practical
limits.
[0003] The connecting rods of belts such as disclosed in the above
referenced patents, and those of other belts of the same general
type, must be retained against lateral movement so as to prevent
them from extending transversely out of the belt, which would allow
the belt to separate between succeeding modules. This need has been
addressed in several different ways. U.S. Pat. No. 4,904,844
describes the use of recesses in end members of the integral
plastic modules or in separate side plate members at the outside of
the belt, to receive connecting rod heads in countersunk
relationship. Such rod heads can be formed in the ends of assembled
rods by deformation of the rod end, sometimes called
"buttoning".
[0004] U.S. Pat. No. 5,181,601 describes a different approach
wherein a connecting rod has an integral, enlarged collar or
interference ring on the rod, to be forced into and engaged with
the inside of a bore in a plastic module, the bore having a
slightly smaller diameter than the interference ring. This creates
a positive press fit engagement between the rod and module, so that
the rod is tightly retained relative to one module. Rod heading
could be eliminated. The same patent also disclosed the use of
three separate connecting rod sections serving as a connecting rod
for each pair of adjacent modules, with the two outer rod sections
retained by the interference fit described above, and a middle rod
section floating between the ends of the outer rod sections.
[0005] Other conveyor belts have employed rod heads, on a one-piece
connecting rod, to retain the rod in the belt.
[0006] Further approaches to retaining connecting rods without rod
heads have been suggested. One approach is a spring clip inserted
into a receptacle in an edge link end, as in U.S. Pat. No.
5,123,524. Other approaches have sometimes involved an integrally
molded tab or flange at the outside edge of a belt module,
positioned to require forcing of the length of the rod past the
somewhat flexible tab or flange (or manually holding back the tab),
with the tab then springing back to an undeformed position when the
rod has been fully inserted. The intention is then for the tab or
flange to prevent outward movement of the rod by interfering with
its path of movement. See, for example, U.S. Pat. Nos. 4,925,016,
5,058,732, 5,156,262 and 5,156,264. Another approach has not
involved a movable tab, but simply a bending path through which the
rod must be pushed at the edge of the belt, so that once forced
into position past the bend, the rod tends not to migrate out from
the belt. The latter type of headless rod retention is shown in
U.S. Pat. No. 5,372,248 and a similar arrangement is shown in U.S.
Pat. No. 5,598,916, where an off-axis hole is provided in a module
edge member. See also U.S. Pat. No. 5,573,106. Examples of other
forms of headless rod retention are shown in U.S. Pat. Nos.
4,993,544 and 4,893,710.
[0007] Some types of headless connecting rod retention cause
excessive wear against the belt module or against a retaining
element or the rod itself, both in radius and linear travel
belts.
[0008] Removal of retaining rods in general has often required the
cooperation of at least two technicians, one to pull the rod from
one side of the belt and the other to push or strike or otherwise
manipulate the rod from the other side of the belt, which can be
impractical.
[0009] It is an object of this invention to overcome problems of
excessive module or rod wear caused by the rod retention system
employed, both in radius and linear travel belts, while also
providing a simple and easily used arrangement for engaging the rod
retention and further for releasing the rod retention when desired.
Another object, in a specific embodiment of the invention, is to
facilitate release of the retaining rod by a single person
operating from only one side of the conveyor belt.
SUMMARY OF THE INVENTION
[0010] A connecting rod retention system in according with the
invention, for straight or radius type modular conveyor belts,
avoids the need for rod heads or any form of movable flange or tab
for locking the rod in place. In addition, the invention in one
preferred embodiment allows a connecting rod to be freely and
easily pushed into the assembled position through two sets of
interdigited projections of successive module rows, without
interference or force required for assembly. Wear of the rod, the
rod retention device and the modules due to the rod retention
arrangement is minimized, in part because the rod is free to rotate
and a retention device on the rod preferably is free to rotate
relative to the rod and is not squeezed or ground between
modules.
[0011] In one embodiment, a rod retention system for a modular
plastic conveyor belt of the character described above includes a
groove or slot in the surface of a connecting rod, located so as to
be between two of the adjacent interdigited projections from the
two successive modules which the rod is to connect. At this narrow
location, the groove or slot defines a smaller diameter or
dimension on the rod than the outside diameter of the rod. A clip,
preferably flat in profile, on its side surfaces, is provided for
engaging over the slot or groove area of the retaining rod, between
the adjacent interdigited projections. The clip is dimensioned so
as to allow it to be forced over the rod at the groove, with the
clip yielding due to its inherent flexibility, and to be retained
on the rod unless a substantial and deliberate force is applied to
remove the clip.
[0012] In a preferred embodiment, the groove or slot is a generally
circumferential groove around the rod, and the clip comprises a
generally C-shaped clip with an open end which is dimensioned to
snap over the groove on the rod, and thence to be freely rotatable
on the rod.
[0013] In one preferred embodiment the connecting rod is formed of
plastic material, and the retaining clip is also formed from a
plastic material, which may be acetal (although a steel rod or
steel clip may be used). The retention system of the invention
avoids wear between the conveyor module itself and the retention
means, while also allowing fast and easy assembly using tools
already available for brass or steel ring retainers used in other
fields. Further, by firmly holding the belt, one can remove any of
the rods with a punch and hammer, which provides sufficient force
to dislodge and pop the retaining clip off the rod and out of the
belt.
[0014] The retention device cannot escape by itself provided the
material utilized for the retaining clip is one with a good memory,
such as the plastic material acetal; this allows the C-shaped clip
to be forced open for assembly, while quickly returning to its
original configuration after being positioned in the rod
groove.
[0015] In some embodiments of the invention, the modular plastic
conveyor belt utilizes discontinuous connection rods such as
disclosed in U.S. Pat. No. 5,181,601. Such a discontinuous
connection rod may include a free-floating middle section and two
opposed edge or side rod sections. With the retention system of the
present invention, the two outer rod sections each have the
retention device of the invention, with a groove and the clip
engaged over the groove; or one end of the belt is closed and the
clip is on the rod section at the opposite end.
[0016] In some belts, particularly radius type belts, the faces of
adjacent interdigited link ends between which the clip is
positioned are reduced in profile. This is to provide ample lateral
space for the clip between link ends, to avoid squeezing of the
clip and wear of the clip and/or link ends due to relative side
forces acting between modules, particularly on curves.
[0017] Another embodiment of a headless rod retention system of the
invention employs a retention rod capable of some degree of bending
without damage, whereby the rod is bent and inserted through the
module row and having been so inserted, reverts to its normal,
straight configuration and is laterally retained therein by a solid
blocking structure provided at each end of each belt module, in the
position of a link end but without a rod hole and not functioning
as a link end. The insertion of the rod is made possible by the
presence of a space inboard of the blocking structure at least at
one side of the module row, free of rod-capturing link ends, which
allows the rod to be inserted without the need for bending beyond
the bending tolerance of the rod. This system allows removal of the
rod by a single person from one side of the belt.
[0018] In a preferred form of the above embodiment, link ends or
projections extend into the spaces noted above, to overlap the
position of the rod, and these link ends are regularly spaced
apart, but each comprises essentially a half-ring structure. The
half-ring projections cradle the rod on its upper side, such that
the rod is unconfined at the bottom of the belt. The half-ring
structures, being open at bottom, enable the rod to be slidingly
inserted into or removed from the generally aligned link end
openings, while providing mechanical interaction and some support
between the rod and the half-ring structures of the special link
ends of each module.
[0019] In one variation of the above embodiment, the connecting rod
is configured into a temporary bend for insertion and removal, but
the end of the rod has a head which, when assembled, resides just
inboard of a belt edge member having a hole. The head prevents the
rod from migrating outwardly.
[0020] In a further embodiment, a headless connecting rod is
retained in the belt via a preformed bend in the rod which becomes
partially straightened when the bend is forced through a hole in
the belt edge structure. Once within the belt, the rod resumes its
prebent configuration, placing the end of the rod offset from the
hole in the belt edge and retaining the rod in the belt.
[0021] Accordingly, a principal object of the invention is to
provide a simple and easily operated and assembled arrangement for
retaining and removing connecting rods in a modular plastic
conveyor belt, without rod heads and without the need for special
moveable elements on the modules. These and other objects,
advantages and features of the invention will be apparent from the
following description of a preferred embodiment, considered along
with the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a plan view showing a portion of a modular plastic
conveyor belt with the rod retention system of the invention.
[0023] FIG. 2 is a plan view similar to FIG. 1 but showing a
portion of a radius type conveyor belt, in a curve, again with the
retention system of the invention.
[0024] FIG. 3 is a detail view showing a part of a connecting rod
for a modular conveyor belt, illustrated with a retaining clip
engaged on the rod in accordance with the retaining system of the
invention.
[0025] FIG. 4 is a profile elevation view of the retaining clip, in
one embodiment.
[0026] FIG. 5 is a plan view of a retaining clip in one
embodiment.
[0027] FIG. 6 is an enlarged detail view showing a groove or slot
on the connecting rod.
[0028] FIG. 7 is a schematic view showing an example of an
alternative form of clip which can be used in the rod retention
system.
[0029] FIG. 8 is an exploded perspective view of a pair of solid
top belt modules of a second embodiment of the invention in which
the connecting rod is forced into a bending configuration for
assembly and removed.
[0030] FIG. 9 is a perspective view of a pair of belt modules as in
FIG. 8, here showing the two adjacent modules serially connected by
a connecting rod.
[0031] FIG. 10 is a bottom plan view of a single belt module as
shown in FIG. 8.
[0032] FIG. 11A is a sectional view as seen along the line 11A-11A
in FIG. 10, showing the cross-sectional structure of the belt
module through a regular link end.
[0033] FIG. 11B is a sectional view as seen along the line 11B-11B
in FIG. 10, showing the cross-sectional structure of the belt
module through a special, half-ring link end.
[0034] FIG. 12 is a fragmentary bottom plan view showing
alternative structure to that shown in FIGS. 8-10.
[0035] FIG. 12A is a side elevation detailed view showing rod
assembly.
[0036] FIG. 13 is a partial perspective view similar to FIG. 8 and
showing another alternative structure.
[0037] FIG. 14 is a perspective view similar to FIG. 8, showing a
similar embodiment with a shorter belt pitch.
[0038] FIG. 15 is a perspective view showing the belt modules of
FIG. 14, connected by a retaining rod.
[0039] FIG. 16 is a bottom plan view of a single belt module of the
type shown in FIGS. 14-15.
[0040] FIG. 17A is a sectional view as seen along the line 17A-17A
in FIG. 16, showing cross-sectional structure of the belt module
through a regular link end.
[0041] FIG. 17B is a sectional view as seen along the line 17B-17B
in FIG. 16, showing cross-sectional structure of the belt module
through a special half-ring link end.
[0042] FIG. 18 is a perspective view showing the end of one module
in accordance with a further embodiment of the invention wherein
the connecting rod has a preformed bend.
[0043] FIG. 19 is a sectional view showing a portion of two
interdigited modules in accordance with another embodiment wherein
the connecting rod has a head located inboard of an edge component
of the belt, again involving bending of the rod for insertion and
removal.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0044] FIG. 1 shows in plan view a portion 10 of a modular plastic
conveyor belt of the type with which this invention is concerned.
In the example shown, plastic integrally molded modules 11, 12, 13
and 14 are held together with retaining rods 16. The retaining rods
16, preferably also of plastic as in previous patents referenced
above, including U.S. Pat. No. 5,181,601, pass through transverse
openings in sets of projections 18 and 20 of the plastic modules
11-14. The projections or link ends 20 may be called fore or
leading projections, and the oppositely-directed projections or
link ends 18 may be called aft or trailing link ends for purposes
of this discussion, although the belt can be driven in either
direction. In the example shown, single modules 11-14 extend
throughout the width of the belt illustrated; however, this is only
one example, and in wider belt assemblies the modules will normally
be assembled together widthwise and in staggered relationship. For
example, a wider belt might have three modules in one row and only
two in the next succeeding row. This avoids continuous module seams
through the belt, adding strength to the belt widthwise. Such
compounding and staggering of modules is well known in the
industry.
[0045] In the embodiment illustrated, retaining clips 22 are
secured onto the connecting rods 16, as illustrated, between
interdigited fore and aft projections 20 and 18. These clips are
locked onto the rods so that the rods are permitted very little
lateral movement in the belt. As can be seen from FIG. 1, these
clips 22 can comprise generally C-shaped retaining clips which are
snapped over the rod, in a groove, slot or otherwise
reduced-circumference portion of narrow width. The grooves or slots
are discussed in more detail below.
[0046] As can be seen from FIG. 1, the rods 16 can be easily
assembled to connect the succeeding module rows, by sliding the
rods through the openings in the interdigited projections 18 and
20. Once the rods are in the position desired, a retaining clip 22
is pushed over the rod and snapped into position, the groove or
slot having been located in the appropriate position between
interdigited projections. Although FIG. 1 shows connecting rods 16
extending from the outermost projections of the modules and of the
belt, these rods can be flush or recessed relative to the surfaces
of the outermost projections, if desired for a smooth belt edge.
Also, different configurations at outermost projections can be
employed if desired, for certain types of belt, particularly the
type of structure shown in FIG. 2.
[0047] In FIG. 2 a radius type plastic modular conveyor belt
portion 25 is shown, of the type disclosed in U.S. Pat. No.
5,181,601, the disclosure of which is incorporated herein by
reference. Three module rows 26, 27 and 28 are illustrated. The
radius conveyor portion 25 is illustrated with integral sideplates
30 (heavier edge projections) as in the referenced patent, and with
discontinuous connecting rods 32 as also shown in the referenced
patent. Each rod in the illustrated embodiment is made up of two
outer or side rod segments 32a, and a center rod segment 32b. The
outer rod segments 32a have a slot for groove 34.
[0048] In a belt designed for radius as well as straight travel, it
is important that the connecting rods 32 be of adequate strength to
retain the entire tension of the belt in a very narrow region at
the outside of the curve, as discussed in the referenced Patent No.
5,181,601. Accordingly, the retaining clips 22 of the invention are
inward from either edge of the belt, at a location where the slot
or groove 34 in the rod will not fall in this region of very high
tension.
[0049] The rod retaining system is best understood with reference
to FIGS. 3, 4, 5 and 6 as well as FIG. 2. The radius conveyor belt
embodiment shown in FIG. 2 is made up of staggered rows of modules
26, 27 and 28 as explained above. Thus, the module row 26 has a
pair of modules 26a making up that row; the module row 27 has left
and right modules 27a and a center module 27b; and the third module
row 28 is similar to the row 26, having left and right modules 28a.
Dividing lines between adjacent modules are shown, for example, at
27c in the row 27 and at 26c in the row 26. Each module row, and
each module, has fore projections or link ends 36 and aft
projections 38 ("fore" and "aft" are used for convenience of
description; the belt can be driven in either direction). As in
radius belts of this type, one set of projections, the aft
projections 38 as illustrated, have slotted openings 40 as the
transverse openings through the set of projections. When the belt
travels around a curve, the outside of the curve, at the right in
FIG. 2, experiences a concentration of belt tension stresses near
the outside of the belt. As explained in the referenced U.S. Pat.
No. 5,181,601, this is the reason for the heavier end projections
or integral sideplates 30 shown in FIG. 2. The rod slots 34 in the
discontinuous connecting rods 32 illustrated, are remote enough
from the outer ends of the belt as to have no adverse effect on the
strength capability of the connecting rods. Outer edge stress is
the most critical concentration of stress in the rod; in straight
belt travel, when the region of the slots or grooves 34 experiences
some degree of stress, such stress is far less than what is
encountered at the edges and is non-critical.
[0050] It is generally sufficient that the slot on groove 34 be
inboard from the outer belt edge by at least two fore projections
36 and two aft projections 38. In the form illustrated, the groove
is spaced inboard by three projections of each type, i.e., it is
located at the sixth inter-projection spacing 39f. The first
inter-projection spacing 39a is generally the location of highest
and nearly all stress. The second such spacing 39b may also take
considerable stress due to rod deformation and slight module
deformation under the high tension in a curve. Thus, at the
minimum, the slot or groove should be at the third spacing 39c or
farther inward; more preferably at least the fourth or fifth
spacing 39d or 39e.
[0051] FIG. 2 shows grooves 34 and retaining clips 22 at both left
and right of the belt section illustrated, i.e. in both outer belt
segments 32a.
[0052] As shown in FIGS. 3 through 6, the retaining clip or ring 22
has a narrow profile, and the belt groove or slot 34 in the rod is
considerably wider. This allows the clip to assume angled positions
such as shown in FIG. 3 and also in FIG. 2, to accommodate the
angled space relationship existing between interdigited projections
when necessary. As one example, if the rod segment 32a and the clip
22 are both formed of plastic material, with the clip being, for
example, Delrin (acetal) plastic, the clip may have a thickness of
about {fraction (1/32)} inch, residing in a groove 34 having a
width about twice as great, e.g. about {fraction (1/16)} inch.
[0053] FIG. 3 shows the ring or clip 22, which is preferably
C-shaped as shown in FIG. 5, being pushed over the slot or groove
34 of the rod or rod segment 32a. As the C-shaped clip 22 is pushed
over the groove, the open end 42 of the clip, which has angled
opening surfaces 44, opens the clip 22 with a camming action, as is
known in metal clips used in other arts. The clip 22, which is
preferably plastic, has sufficient flexibility to spread the
opening 42 in order to slip over the groove 34 of the rod, and
sufficient "memory" to return to its original configuration, thus
capturing the clip on the rod. As an example, the open end 42 of
the clip may have a minimum dimension of about 0.08 inch, while the
diameter of the rod groove may be about 0.116 inch. The depth of
the groove or slot 38 may be about 0.02 inch, thus the outer rod
diameter being about 0.156 inch in one preferred embodiment which
is appropriate for the dimensions outlined. Connecting rods, of
course, can be of different outside diameters, depending on the
materials used, the specifications and loads on the belt, and the
pitch of the belt.
[0054] As seen in FIG. 2, in the module row 28 which is lowermost
on the page, the inter-projection spacing 39f, i.e., the spacing
wherein the reduced-circumference slot or groove 34 is located, may
have projections 38a and 36a of reduced profile. This is especially
important in radius-type conveyor belts as illustrated in FIG. 2,
because of lateral forces acting between succeeding modules under
the stress of travel around curves. In many instances, the
retaining clip 22 can be squeezed and rubbed with sufficient force
to cause wear on the retaining clip, the projections on either
side, and possibly the rod. This can occur, for example, in the
interdigited projections 36, 38 which connect the module row 26 to
the module row 27 in FIG. 2, where no reduced-profile projections
are shown. The lowermost line of interdigited projections in FIG. 2
shows the inter-projection spacing 39f as enlarged due to reduction
of the sides of the adjacent projections 36a and 38a. These
adjacent projections preferably are formed or ground to essentially
a planar surface which is perpendicular to the width of the module
row. This provides a wider spacing for the clip 22, a spacing which
is free of the typical angled projection ends which are included in
radius conveyor modules. The spacing 39f thus is essentially
rectangular (although a very small angle exists between the
adjacent projections 36a and 38a) and which cannot completely
collapse to the point of squeezing, rubbing or grinding on the clip
22. A minimal spacing is assured because of the interaction of link
ends or projections closer to the outermost edge, such as at
inter-projection spacings 39a, 39b, 39c and 39d.
[0055] It should be understood that other configurations of rod
slots and Clips can be employed. For example, the slot in the rod
could be non-continuous around the rod, merely sufficient to enable
some form of clip to be securely and positively located on the rod
at the desired position and captively held thereon. Some form of
indentation in the rod is required for this purpose. Clips can take
different forms, although the C-shaped clip or ring 22 illustrated
is preferable and advantageous. As another example, a clip formed
of stiff metal wire, in the configuration 46 generally as shown in
FIG. 7, could be employed. In the preferred embodiment, the
generally C-shaped clip such as shown in FIGS. 3, 4 and 5 can have
the advantage of being freely rotatable and capable of angular
displacement within the groove as discussed above. For this
purpose, the diameter of the C-shaped interior bore of the
preferred clip 22 may be about 0.118 to 0.120 inch, as compared to
the rod diameter of about 0.116 inch in the groove. This gives
sufficient clearance for angling of the clip within the groove as
shown in FIG. 3 and in FIG. 2.
[0056] FIGS. 8 and 9 show in perspective, from the bottom side, an
embodiment of the invention wherein a retaining rod 55 is threaded
through transverse openings 56 in spaced apart fore and aft
projections 59, 59a (sometimes called link ends herein) and is
prevented from moving laterally by solid blocking structures 60
positioned at opposed ends of each belt module 61. In the modules
illustrated the link ends 59 on a first side are longer than link
ends 59a on a second side, with a transverse member 65 which is
offset from the fore/aft center of the module. The modules may be
driven by sprocket teeth entering spaces 64 formed between the link
ends 59 and by the transverse members 65, and opposite the member
65, by the opposing link end 59a of a connected adjacent module
(FIG. 9).
[0057] In this embodiment a space 62 inboard of each blocking
structure 60 allows insertion into the module row of a rod, by
forcing the rod through a bend. Having been so inserted, the rod
reverts to its unbent essentially straight shape. The length of the
space at the end of each module row is such that it allows the rod
to be inserted without the need for bending the rod beyond its
mechanical tolerance and without the need for the application of
more force than can be reasonably supplied by a single
technician.
[0058] Open half-ring structures 63 project into the spaces 62,
cradling the inserted rod 55, such that the rod is unconfined at
the bottom of the belt, but is cradled on its upper surface,
preferably throughout about half its circumference. These half-ring
structures, being open at bottom, enable the rod to be easily
inserted or removed from the generally aligned transverse openings
56, while also providing mechanical interaction and some degree of
enhanced support due to the contact between the rod and the
half-ring projections close to the ends of the module. FIG. 9 shows
the arrangement of two such belt modules serially joined by a
retaining rod 55. This embodiment of the invention allows a single
technician to remove or insert a retaining rod from one side of the
belt, using pliers or a special tool, without the need for
assistance at the other side of the belt to manipulate the module
or rod or apply force to the rod. Preferably the rod is not
required to bend more than about 45.degree., for example, for a rod
made of acetal or nylon and about 1/8 to {fraction (3/16)} inch
diameter. More preferably, the rod should be required to bend not
more than about 20.degree.. The rod's configuration on insertion or
removal is shown in FIG. 10A, with the angle a shown between the
pivot axis and the rod 55, due to the bend in the rod. FIG. 12
shows in section one end of two assembled modules, with half-ring
link ends 63 from the two modules shown interdigited. The modules
are inverted, bottom side up, for consistency with the other
drawing figures.
[0059] FIG. 10 shows in bottom plan view a single belt module 61 of
the configuration shown in FIGS. 8 and 9. The projections 59, which
may be regularly spaced apart, are shown with transverse openings
56 through which the rod 55 is to be threaded. The half-ring
structures 63 are at outer ends of the module, located at the
spaces 62 at the end of each module 61.
[0060] Although the drawings show single modules having the
blocking structures or closed link ends 60 at each end of each
module, this only illustrates modules for use on a narrow belt,
e.g. about 6 inches. In most cases the belt will be wider,
comprised of module rows each including several modules withwise.
In that case, edge modules will have blocking members 60 at one
end, but the other end of such a module will be adapted to be
abutted with another module widthwise, to form a wide belt whose
other end has an edge module with a blocking structure. Interior
module edges can be generally as shown in U.S. Pat. No. 5.181,601
of KVP Systems, Inc. For this reason, FIG. 10 is shown with break
lines indicating the module can be virtually as wide as desired,
with the blocking structures 60 at each end of FIG. 10 representing
the ends of edge modules in most cases, although the structures
shown in FIG. 10 can represent ends of a single module.
[0061] FIG. 11A shows in cross section the structure of the module
shown in FIG. 10. FIG. 11 shows the module structure as taken
through a regular link end 59a at the second side of the module
having the shorter link ends, and through a spacing between the
regular link ends 59 at the first side of the module with the
longer link ends. FIG. 11B, on the other hand, is taken along the
line 11B-11B in FIG. 10 and shows the half-ring link end 63a from
the second side of the module (not in section) and a half-ring link
end 63 at the first side of the module (in section). FIG. 11B also
reveals, beyond the half-ring link end 63, a portion of the
blocking structure 60 at the end of the module. FIG. 11B
additionally shows the transverse member or cross member 65 of the
module, which is displaced toward the second side of the module in
this particular embodiment of solid top module, as discussed
above.
[0062] It should be understood that the half-ring link ends 63 and
63a at the ends of the first and second sides of the modules or
module rows can be configured differently. FIG. 12 is a partial
bottom plan view showing an alternative construction in which a
solid structure 66 replaces the two half-ring link ends 63 shown at
the right side of FIG. 10. The single structure 66 extends through
the same width, i.e. through the space 62 shown in FIG. 10. (The
half-ring structure 66 may be formed as a half-cylinder (or less
than a half-cylinder), extending widthwise to and adjoining the
blocking structure 60 at the edge of the module. Thus, a connecting
rod is partially cradled by the wide half-ring structure 66.
[0063] To the left of the structure 66 in FIG. 12 is a gap 68 to
accommodate a link end 59a from an adjacent module, similar to the
link end 59a at the other side of the belt shown in FIG. 12. In
this arrangement, no half-ring link ends are included at the second
side of the module, between the illustrated regular link end 59a
and the edge of the module. In this area the module simply has an
angled edge 64 which is similar to the edges 64 shown in FIGS. 11A
and 11B, shaped to engage against the exterior barrel shape of a
succeeding link end, but in this case against the barrel shape of
the wide half-ring structure 66.
[0064] A further modification (not shown) is that the half-ring
structure 66 of FIG. 12 need not have the full half-cylindrical
shape but need only have a downward curve at the leading edge
(which could be the trailing edge of the module), providing a
partial barrel shaped surface adjacent to which an angled edge 64
of an adjacent module is positioned in the assembled belt, so that
the closed-top belt remains essentially closed as the belt bends at
connecting rods traveling around a sprocket.
[0065] FIG. 13 shows a further variation of the structures shown in
FIGS. 8-12. This embodiment has a thicker end link providing a
blocking structure 70 defining a ramp 72 which is included to aid
in insertion and removal of a connecting rod, by helping to guide
the rod.
[0066] FIGS. 14-17B show a smaller-pitch embodiment of the modules
and belt section shown in FIGS. 8-12. In this form of the module
and belt, which still may be a solid top embodiment, the pitch is
so short as to provide only a very slender flat portion at the top
of each module, best seen at 74 on the underside of the belt in
FIG. 16. As in the earlier embodiment, at each end of the belt (and
shown on a single module 76 in FIGS. 14 and 15) is a solid blocking
structure 78 adjacent to a space 79 wherein a connecting rod is
unconfined from the bottom side. Although both left and right sides
of the module 76 are shown blocked, the belt usually is formed in
much wider widths, and a typical module would have only the
blocking structure at one end, to mate widthwise with an additional
module for staggered assembly of module rows so that seams between
adjacent modules are staggered from row to row, as shown in the
earlier KVP patent referenced above. Thus, FIGS. 14-17A show
blocking structures 78 on both ends of a single module only for
purposes of illustration, although a narrow, single-module width
belt can be formed in this way if desired. FIG. 16 shows the module
broken, so that the structure in FIG. 16 can comprise a belt width
with several modules between the module ends at left and right in
the figure. The modules shown in FIGS. 14-17A can have a pitch of
about one half inch, which has an advantage of allowing the belt to
form a tight return over a roller or series of sprockets, providing
for transfer of relatively small articles from belt to belt.
[0067] As in the earlier embodiment, the modules shown in FIG.
14-15 have first and second sets of normal projections 80 and 80a,
and first and second sets of half-ring edge projections 82 and 82a.
Variations of this structure can follow the variations shown in
FIGS. 12 and 13 and as discussed in the description of those
embodiments. A connecting rod 84 is inserted into and removed from
the belt in the same manner as discussed above, by bending the rod
as it is inserted or removed (FIG. 10A), to clear the blocking
structure 78. Once inserted, the belt resumes essentially its
straight and undeflected configuration.
[0068] FIGS. 17A and 17B are similar to FIGS. 11A and 11B, showing
cross sections of the smaller-pitch modules 76 at different
locations 17A and 17B-17B of FIG. 16. Again, a beveled or sloped
edge 64 is shown where the module engages closely adjacent to the
barrel of an adjacent link end to establish the closed-top
structure of this embodiment.
[0069] FIG. 18 shows another form of rod retention according to the
invention. A module 88 (shown inverted), an end portion of which is
shown in FIG. 18, is generally similar to the modules shown in
FIGS. 8-11B, but preferably with a smaller space 90, adjacent to an
edge member 92, which space 90 has no rod restriction from the
bottom. The module portion 88 shown in FIG. 18 is indicated with a
connecting rod 94, but without showing the adjoining module which
is to be interdigited with the module 88, i.e. with the illustrated
module's rear link ends 96 assembled side-by-side with front link
ends 98 of the adjoining, not-shown similar module. The space 90
includes a half diameter rear link end 100, and on one side of this
link end 100 will be received a regular front link end 98, while on
the other side will be inserted a half width front link end 102
which is shown at the front of the module 88. The space 90 can be
wider if desired, and the half width link ends 100, 102 can be
replaced with somewhat similar structure which does not envelop the
connecting rod at all.
[0070] The module embodiment 88 of FIG. 18 has a connecting rod
hole 104 in the edge member 92, preferably aligned with all other
openings in the link ends 96 which receive the connecting rod 94.
At an opposite side of the module 88, or of a row of modules, is an
edge member which may be similar but without a rod opening, thus
serving as a blocking member at the opposite edge of the belt. The
rod 94 is retained within the belt by virtue of a preformed bend
106 in the rod. The plastic rod 94 is sufficiently flexible that
the preformed bend 106 straightens to an almost linear
configuration when the rod is inserted through the hole 104 and
through the link ends 96, 98 of adjacent interconnected modules
until the bend 106 reaches the edge member 92, at which point the
rod is pushed with light to moderate force through the opening 104.
The rod then springs back to its preformed configuration with the
bend 106, putting that end of the rod offset from the rod opening
104 and preventing the rod from moving out of the belt.
[0071] FIG. 19 shows a further embodiment of the invention wherein
a rod 110 is retained within a pair of assembled, interdigited belt
modules 112. In the embodiment of FIG. 19 the belt portion is again
shown inverted. In this embodiment, the rod 110 has a head 114,
which prevents the rod from lateral movement out through a hole 116
in an edge member 118 of the belt. The belt may have similar end
openings 116 at both ends, with the rod having the head 114 only at
one end. In this way, tooling is similar for modules which are to
be interconnected by rods having heads formed at the exterior of
the edge members 118, or connected by rods as shown in FIG. 19. The
rod 110 is inserted and removed from the bottom, by flexing the rod
a sufficient distance to clear the blocking end structure 118,
including passing the rod head 114 under this structure. As shown
in the drawing, a recess 126 is provided to receive or cradle the
rod head 114 after the rod has been fully assembled in the belt.
This recess both allows the belt to resume a linear configuration
after insertion, and helps prevent lateral movement of the rod in
the assembled belt.
[0072] The sectional view of FIG. 19, taken at the center of the
connecting rod 110, shows a module 112 which is in many respects
similar to those of FIG. 8, interconnected with a trailing module,
a regular link end 120 of which is seen at the left of the
fragmentary belt portion shown in the figure. Additional link end
structures of the trailing module, shown at 122, may be half-ring
link ends such as shown at 100 in FIG. 18 or at 63 in FIG. 8, for
example. Alternatively, they can simply provide a relatively flat
bed on which the rod 110 lies. FIG. 19 also shows interdigited
special link ends 124 of the module 112 which has the blocking edge
structure 118, and these interdigited link end structures will
follow the same form as the link end structures 122.
[0073] The above described preferred embodiments are intended to
illustrate the principles of the invention, but not to limit its
scope. Other embodiments and variations to these preferred
embodiments will be apparent to those skilled in the art and may be
made without departing from the spirit and scope of the invention
as defined in the following claims.
* * * * *