Note: Descriptions are shown in the official language in which they were submitted.
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Description o~ the In~ention
The present invention relates to'an-improved drive
unit ~or accumulation live roller conveyors In particular
the present invention relates to a drive unit which functions
to selectively drive mul~iple rollers simultaneously.
Prior Art
Live roller accumulation conveyors are well ~nown
to the prior art. The present in~ention is concerned with -r
conveyors which are constructed with frictional drive units
such that the power source can be disconnectea from the
rollers as articles accumulate on the pass line so that
the articles do not press against each other or what is
termed in the art as "zero pressure" accumulation. One
mechanism which disconnects the rollers is a trigger or
sensor on the pass line which when depressed by an article
moves a mechanical linkage which disconnects the power
source from the rollers. Usually the linkage is a
mechanical rod or axm which is moved by the passage of the
article over the pass line trigger; however, sometimes air,
pressure bellows or solenoias or other motive means are
activated by the trigger to move the linkage.
~ . S. Patent Nos. 3,012,652 (Poel); 3,612,248
~Wallis); 3,643,788 (Werntz); 3,730,330 ~ J. DeGood) and
3,810,538 (Moyes) disclose such prior art devices. Each of
these patents show a conveyor wherein one or more of the
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rollers is moved by selectively frictionally contacting the
rollers with a rotating frictional drive belt provided under
the pass line ('248, '652, '788 and '300) or by selectively
contacting the frictional drive belt with a rotating power
means ('538). These devices operate reliably but are relatively
complicated and expensive to construct. Also they have pinch
points which may not be covered and which can cause safety
problems.
Objects
It is therefore an object of the present invention to
provide an improved live roller accumulation conveyor which is
simple and inexpensive to construct and which has a single
drive unit for the frictional drive of multiple rollers. It is-
particularly an object of the present invention to provide a
means for powering the multiple rollers by means of multiple
frictional drive surfaces provided on rotatable drive wheels
which are pivotably and arcuately movable into and out of
contact with multiple rollers and which also very rapidly
responds to the application of the power.
Summary of the Invention
Broadly speaking, the present invention meets the above
objects by providing the drive unit for a live roller accumulation
conveyor with a plurality of rollers mounted on longitudinal
axes atboth ends on a frame in spaced relation so as to define
a pass line on surfaces of the rollers for transport of articles
by the rollers which comprises: (a) a support bar positionable
on the frame of the conveyor along the pass line adjacent the
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axes of multiple rollers, the support bar being adapted to be
arcuately pivotable about an axis parallel to the pass line
towards and away from the axes of the rollers; (b) multiple
drive wheels adapted to be powered each having or adapted to
receive a frictional drive surface and rotatably mounted on
shafts in spaced aligned relation on the support bar so that
frictional drive surfaces on each drive wheel can come into
contact all at the same time with two roller surfaces upon
arcuately pivoting the support bar and the drive wheels towards
the axes of the rollers; and (c) means on the support bar adapted
for pivoting the support bar when mounted on the frame.
In the Drawings
Figure 1 is a front view of a partial cross-section
across the frame rail oE a half section of the preferred
improved conveyor in a powered roller position illustrating a
driven belt as a frictional drive surface which also rotates
one drive wheel mounted on a support bar which arcuately pivots
the belt so as to frictionally engage a tapered end surface of a
roller.
Figure 2 is an end view along line 2-2 of Figure 1 of
a cross-section through eight spaced apart adjacent rollers
illustrating resilient belts mounted on four drive wheels rotatably
mounted on the pivotable support bar, each belt being positioned
for engagement with a portion of the tapered end surfaces of
two rollers.
Figure 3 is a front view of the support bar for the
: B multiple drive wheels shown in Figures l and 2 particularly
illustrating legs on a cross member comprising the support bar
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and slots forming the pivot points on the legs for mounting
on the frame.
Figure 4 is a top view of the support ~ar shown in
Figure 3 particularly illustrating the positioning of a plate
for the connecting rod for movement of the support bar.
Figure 5 is an ena view of the support bar shown in
~igures 3 and 4 particularly illustrating dual stops for
preventing over-run of the support bar in either direction of
arcuate movement by contact with the frame.
Description of the ~nvention
In our Canadian Application Serial No. 296,~66 filed
February 3, 1978, we described a drive unit wherein an arm
supporting a single drive wheel was arcuately pivotable into
contact with a tapered end surface of a roller. There was a
need to improve upon this drive unit since each drive wheel
required a separate powered linkage for powered movement of the
arm which resulted in the present invention.
In F~gures 1 and 2, live rollers 10, each having a longi-
tudinal axis lOa, are shown which form a part of a pass line on
a conveyor. The rollers 10 are mounted rotatably on their longi-
tudinal axes lOa in a channeled frame rail 11 by means of hexagonal
shafts 12 which are attached to the frame rail 11 and ta the
rollers 10 by means of conventional internal roller bearings
~not shown). The framerail 11 includes an upper inner lip lla for
mounting the shafts 12 and a lower lip llb facing inwardly towards
the rollers 10 which shield a drive unit. The rollers 10 together
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define an article carrying surface 13. A tapered surface 14 is
provided at one end of the roller(s) 10 to be powered. As
can be seen from Fig~re 2, eight spaced apart,
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adjacent rollers 10 have tapered surfaces 14 and are
powered by a single drive unit.
Attachea to the frame and between and below the
adjacent rollers 10 is pro~iaed the drive unit including
5 multiple drive wheels 15 each defining a circumferential
groove 17. The drive wheels 15 are each rotatably mounted
on their radial axes on a round cross-sectioned fixed or
welded bolts 16 by nuts 16a. Conventional roller bearings
(not shown~ are provided in the drive wheels 15. The drive
10 wheels 15 on bolts 16 are mounted on a support bar 18 which
is.pivotable-at point,l9 to move.the drive wheels 15 tan-
-~eniially into a closely-.spaced r~lationship..with the
tapered-sur-f~ces.-.14-.~n_-the-:rollers l-0. .
In the preferred-formj--:-coii-springs 20 or-other
15 resilieDt means attached-between-the support bar 18 and the
frame are provided which urge the support bar 18 and drive
wheels 15 towards~the-taperea--surfaces---1-4.- Cross members
or bars 21 are attached.between frame rails 11 (only one
of which is shown.in Figure l).in.spaced.parallel relation-
20 sh~p to the rollers 10 by means of rivets 22 in order to
~ join spaced apart-frame rails 11 and the rails 11 and bar
.. 21 form the frame.
Resilient high friction belts 23 ~preferably cir-
cular..in..cross-section) are mounted in the groove 17 of
25 each drive wheel 15 such that a small circular segment or
surface of the belt 23 frictionally engages the tapered sur-
faces 14 when the drive wheels 15 are in their most extended
pO3ition due to the urging o~ the springs 20. The outer
rim 15a of the drive wheels 15 must be large enough in
. 30 diameter so that the belt 23 does not slip out of the groove
17 because of the lateral forc~ along the axes 10a of the
rollers 10 exerted by taper 14 of the roller 10 on the belt
23. The inner rim 15b is designed to be in closely spaced
r~ation to the surface 13 beneath the roller 10.
Spaced apart from the drive wheels 15 and support bar
18 is a rotata~le drive shaft 24 which is mounted along the
` pass line formed by the rollers 10. The shaft 24 rotates
in journals 25 mounted by means of bolts and nuts 25a on
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the underside of the cross members 21 (Figure 2). Spools
or bushings 26 are mounted on the drive shaft 24 and are :~
fixed in position on the shaft 24 beneath each drive
wheel 15 ~y allen screws 27 (Figure 2) or the like. The
belts 23 are in tension on the bushings 26 so that they
are in turn in tension on the drive wheels 15 in the grooves
17 so as not to slip. The drive shaft 24 is powered by a
motor or other moti~e means usually at one end (not shown).
As indicated, the support bar 18 is mounted on cross
bar 21 at pivot point 19 such that the support bar 18 can
rock or pivot towards and away from the tapered surface 14.
The.suppo~t bar 18.is shown in detail in.Figures 3 to 5.
The_~upport-bar 18 includes two legs--28 ~ounted,-on cross
piece~.29 which-supports ~he bolts 16 for mounting-the drive---- -
1~ wheels 15. Slots--30.are provided at $he distal end of ea,ch
of the legs 28 which mate with slots 31 in the cross member
21 to form the pivot point 19. The support.bar 18 is moved
by a linkage or arm-32 (Figure l)'~loosely'''attached to the
support bar 18-by a bend 33 in the arm 32 positioned in a :
hole 33 in a plate 34 attachea to the center of the cross
piece 29. The linkage 32 is moved by an air bellows 3~
mounted on the cross piece 21 by a bracket 36 and powered
by an air line 37 attached to the bellows 35. The bellows
35 has an internal diaphragm (not shown) which is movea
by applying air pressure in line 37 to move the linkage 32
and thus the support bar 18 away from the axes lOa of the '.
rollers 10. The bellows 35 can also be operated on the other
side of the diaphragm by means of a vacuum (not shown).
Stops 38 and 39 are provided on the back side of the cross
piece 29. The stop 38 contacts the ~rame rail 11 when the
arm 32 is extended to prevent dislocation o~ the legs 39
rom the pivot points 19. The stop 39 contacts the inside
of the inner lip lla on the frame rail 11 to pre~ent the
.springs 20 from pulling the belt 23 into too tight contact
with the taper 14. All that is required is a firm contact
between the taper 14 and belt 23. .The sprlngs 20 are
attached through holes 40 in legs 38.
As shown in Figure 1, the cross member 21 is adapted
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to be matea to rollers 10 of varying length by means o
short cross members 21. The end 21a of the cross member 21
has an extension 36a of bracket 36 welded to it and holes
41 are provided on either side of the extension 36a to
receive bolts for attachment of extensions to t~e other
side rail (not shown). Alternatively the cross member 21
can be a single piece between frame rails 11 on either side
of rollers 10.
In operation, the springs 20 urge the rotating belts
23 into contact with the tapered surfaces 14 to power the
rollexs 10 and also hold~the-slots-30 and-31 together-at the
pivot point l9.~~~When an arti-~le-(not---shown)~moves on--the
pas~ line downstream--~rom.~e r~llers--10,--a-:trigger-.~ar._.
(not shown)- is depressed.which-opens a.val~-and-supplies
air pressure to the bellows 35. The linkage.32 moves the
support bar 18 outward toward the frame rail 11 and dis-
~ connects the~beIts-23~from-~frict~onal-enga-gem~nt~wit-h---the~
tapered surfaces 14. If the article merely rapidly passes
over the tr~gger bar, the belts 23 rapidly re-engage the
tapered surfaces 14; however, if the article is halted on
the pass line, then the belts 23 remain disengaged from the i~
tapered end surfaces 14.
As shown in Figure 1, the belts 23 engage a tapered
end surface 14 of the rollers 10 which is preferred.. It
will be appreciated that the drive wheels lS can engage
any of the surfaces 13 of the rollers 10, such as where the
longitudinal axes lSc of the drive wheels 15 are tilted
at.an.acute angle to the--longitudinal axes of the rollers
10, rather than being almost parallel as shown in Figure 1.
In this event the rims 15a and 15b of drive wheels 15 need
to be shaped and of a diameter so that the belts 23 readily
engage the surfaces 13 of the rollers 10.
It will be appreciated that various means-for driving
the drive wheels 15 can be used, such as motors and the like,
3S and preferably the drive wheels 15 operate synchronously
and in the same direction of rotation. In this event, the
drive wheels 15 have a radial circumferential frictional
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drive surface which engages the surfaces 13 preferably the end
surface 14 of the rollers 10. Such modifications are described
in detail in our Canadian application Serial.No. 296,226 filed
February 3, 1978.
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