Note: Descriptions are shown in the official language in which they were submitted.
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ACCUMULATING CONVEYOR
The pre~ent invention is directe~ to an
accumulating conveyor upon which articles may be ~tored or
accumullltHd to be advanc~d to ~ work ~tution only wherl the
work ~tation is r~ady to receivc an artille.
A typical application of 3uch conveyor is in a
production line where, due to the nuture of Rn OperatiOI)
per-formed on the article at the work st~stion, the rate at
which articles are di~charged from the work station i~ ~
variable rate or a rate which i~ less ~than the rate at which
article~ cQn be supplied to the work station. When the work
station is occupied, thc conveyor function~ to halt the flow
of articles to the work btHtion, thus accu~ulating a line of
articles up~tream from the work station ~o that articles can
be ~upplied to the work station as fa~t ~s the work station
i~ zea~y to H(`Cept them. The bsic re(luirem~nt oY ~uch ~1
conveyor is that it must be able, while being continuou~ly
operated to advance article3 intermittently in accordance
with the requirements of the work Ytation.
In the prior art, a walking heam type corlveyor is
convention~lly used to perform the foregoing function.
Uniformly spaced article receiving seats are located a~ong
the fixed frame of the conveyor and a lift-and-cQrry
mechanism i9 as~ociated with each ~eat which is operable in a
~Yk
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cyclic sequence to li*t and carry an ar-ticle from one sea-t to
the next advanced seat to advance the articles in step-by-
step movement along the conveyor. The various Lift--and-carry
mechanisms are interlinked with each other so that only those
lift-and carry mechanisms whi.ch are upstream from an empty
seat will be actu~ted -to advance articles in an operating
cycle. Prior art examples of such conveyors are found in
United States Patents 4,441,606 and 4,240,642.
While the walk:ing beam type accumula-ting conveyor
is widely used, it possesses certain inherent drQwbacks. A
lift-and-carry mechanism must be provided at each station,
together with a sensing mechanism at each station which
detects the presence or absence of a part or article at that
station and signals all upstream stations as to whether they
are to act in the transfer or non~transfer mode durin the
next cycle. The intermittent step-by-step operation relies
upon a reclprocatory drive mechanism wh:ich subjects a
multi-tude of interconnected system parts to impact loading a-t
stroke reversal and which is subjected to variable loading,
depending upon the number of parts which are to be advanced,
upon the actua-ting stroke. The articles conveyed in turn
must be bodily lifted from the conveyor frame, advanced, and
then lowered gently back onto the CODveyOr ~rame a
substantial number of times in order to transit the conveyor.
The accumulating conveyor of my U.S. Patent Number
4,~98,818 was designed to overcome these problems. It
employs a pair of multiple s-trand roller chains operatively
trained about paired end sprockets for coordinated movement
along an endless path having horizontal upper and lower runs
0 extending between the end sprockets. One strand of each
33 ~'~3
roller chain :is operat:ively trained about one set of end
~prockets while a second ~trand of each chain ;s ~upported
laterally clear- o~ the end ~prockets by -track means employed
to ~upport and guide the chain~ along the.ir upper and lower
runs. A plurality o~ article carr:iers are mounted to sxtend
between the two chain~ and to be supported from the 3econd
strands o-f the chains by outer and inner support plates
fixedly mounted at -the opposite ~ide~ of each carrier. The
outer ~upport plates support the c~rriers up~n the chain~
during tran~i-t vf the upper run while the inner ~upport
plates suspend the carriers in an inverted po~i-tion during
trao~it of the lower run by the frictional engagcment of
chain engaging edge~ on the plates with the chain rollers.
The chaill is continuously driven and, because of the
frictional coupling between the carriers and chaiDs, carrier-
~may be accumula-ted or held stationary by ~uitable stops at
selected locations along either the upper or lower run.
To transfer carriers around the curved portion~ of
the chain path de-fined by the end sprocke-ts, the spacing and
configuration of the opposed edes of the inner and outer
support plates are designed to automatically positively
couple the carrier to the chain as the carrier moves from the
upper or lower run into the curved portions of the chaiD
path.
The length o~ the straight edge section of the
inner plate, its spacing from the oppo~ed straight edge
section-of the outer plate, and the inclination of the
beveled edge sectioD~ of the inner plate are related to the
end sprocket radius and the pitch of the chain in a fashion
such that when the carrier moves onto the curved portions of
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the endless path defined by the end sprockets, the corner3 at
the juncture~ of the straight edge section and beveled edge
~ections of the inner plate project into the spaced between
t~o adjacent roller~ of the chain and are po~itively held in
this position by the tangenti.al engagement o-~ -the stra:ight
edge of the outer plate with a roller ~idway between those
~: two se-t~ of roller~ engaged by the inner plate. This ac-t:ion
provides a positive coupli.ng between the carri.er and the
cha:in QS the carr:ier transit~ the curved por-t:ion~ o~ the
endles~ path ~o that the carriers can be transported from the
lower run upwardly around one set of end sprockets to the
upper run and be restricted to movement with the chain as the
carrier is passed downwardly around the other end sprockets
trom the upper run to the lower run.
My co-pending application serial number 850,2fiO
represents a ~urther refinement to the above described
system. In the co-pending application, the carrier is
positively coupled to the chains during transit oP the curved
portions of the path defined by the ~procket means by concave
recesses at opposite ends of the straight ede section of the
inner support plate. The rollers o~ the chain are seated and
held by the tangential engagement of the straight edge o~ the
~ opposed outer plate with a roller intermediate the seated
- roller~.
While the accumulating conveyors disclossd in ~y
:~ above-referenced patent and co-p0nding application are
~uccessful in overcol~ing the proble~s cited with the prior
art, they do require that the spacing between the chain
engaging edges, the length o-P the straight edge section and
beveled edge sections of` the inner plate, the radius of -the
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~procket means, the pitch of the chains, and the size oP the
concave reces3es exhibit particular and fixed relationships
to each o-ther. Hence, th~ tolerance permitted in the sizes
and spacings of the various components is relatively ~malL.
This factor can ~lake these conveyors relatively expensive to
manufacture and difficul-t to set up and operate.
The present invention is des:igned to overcome thi~
problem.
[n accordance with the present invention9 a
resiliently surfQced wheel i~ mounted for rotation about each
of -the axes about which the end sprocket rotate. The
resiliently surfaced wheel is positioned on the axis for
engagement with the wheel engaging edge of the inner support
plate on a carrier of the type described above when the
carrier is in transi-t. On the oppo~ite edge of the inner
support plate from the chain engaging edge is formed a wheel
engaging edge in parallel and spaced apart relation
~;~ therefrom. The radius o-f the wheel exceeds the distance
between the respective axis and the wheel engaging edge of
the inner support plate of the carrier at its closest
approached thereto so as to bias the chain engaging edge
against the chain and prevent vertical slippage between the
;~ chain engaging edge of the carrier and the chain as the
carrier travel~ around the end sprockets from the upper run
of the coDveyor to the lower run, and vice-versa.
Because of the biasing force transmitted by the
resilient ~urface of the wheel as it rotates, the chain
engaging edge will firmly engage the rollers of the chain.
Because -the resiliently surfaced wheel is provided -to the
conveyor a-t each sprocket end thereof, -the biasing force
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comes into e:ffect precisely when needed, that i~, when the
carrier is subject to vertical ~lippage with re~pect to the
chain because it is negotiating the vertical di~tance between
two diPferent hori~ontal levels of the conveyor.
While it is believed that the bia3ing ~orce alone
provided by the resiliently surfaced wheel is ~ufficient, in
most cases, adequately to prevent the vertical slippage, .it
may also be Rdvantageous to shape the chain engaging ~urface
of the inner plate in the manner described in my U.S. Patent
Number 4,5g8,818. Thus, the chain engaging surface m~y
comprise a straight section with two beve:led edge ~ections.
This design will serve to cause even more secure engagement
be-tween the chain and the biased chain engaging surface of
the inner support plate.
Other object~ and features of the invention will
become apparent by reference to the following specification
and to the drawings.
Figure 1 is a side elev~tional view of an
accumulating conveyor embodying the present invention;
Figure 2 i9 a top plan view of the conveyor of
Figure l;
Fig-ure 3 is a detailed transverse cro~s-sectional
view of the conveyor taken on line 3-3 of Figure l;
Figure 4 is a detailed side elevational view of a
carrier embodying the present invention; and
Figure 6 is a ~chel~atic diagram showing the
relationship between the carrier support plates and chain at
various locations along the endless path o-f the chain.
The overall arrangement of the accumulating
conveyor shown in Figures 1-3 of the drawings is very similar
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to that disclosed in my aforementioned IJ.S. Patent Number
4,598,818. The conveyor includes Q ~rame designated
generally 10 upon which are rotatably mounted two paired set~
of snd sprockets 12 and :L4, end sprocket ~et 14 being coup.led
to an insertable drive means designated generally 16. A pair
o-~ end:LQss multiple strand roller chains 18 are operatively
trained about end sprocket sets 12 and 14 and are maintained
in tension by a suitable chain tenslon.ing device of
conventional construction designated generally by 20 which i~
operatively coupled to end sprocke-t set 12. The sprockets of'
sprockeI: set~ 12 and 14 are all of like radiu~ and th~ chain
18 extends between sprocket se-ts :l2 and 14 in horizontal
upper and lower runs 22 and 24, shown in Figure 1.
I
~ Referring now to Fi~ure 3, it is seen that the
:~ multiple strand chains 18 kake the form of a triple strand
roller chain having strands 18a, 18b and 18c The strands
18a and 18b are supported and guided in their movement along
upper and lower runs 22 and 24 o~ the endless chain path by
chain guarding tracks designated generally 26 which are
fixedly mounted upon frame 10 of a conveyor to ~lidably
receive and guide the strands 18a and 18b of the chain.
: Tracks Z6 extend substantially the entire length of the upper
runs 22 and 24 but terminate Rhort of the respective end
sprockets. One or both of the strands 18a and lBb are in
mesh with the sprockets. The third qtrand 18c of the chain
projects laterally clear of the tracks 26 and is likewise
laterally offset from, and does Dot engage with, any o~ the
sprocket se-ts 12 or 14. Strands 18c are employed to support
and convey article carriers, designated generally Z8, along
the endless chain path.
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Referring now particularly to Figures 3 nnd 4, each
article carrier 28 includes a ~ain frame member 30 which, as
best seen in Figure 3, extends transversely of the conveyor
between the two chains 1~. Outer support plates 32 are
fi~edly ~ounted upon frame member 30 adjacent each end of
member 30 in vertical alignment with strand 18c of the
respec-tive chains, and inner support plates 34 nre likewi~e
fixedly mounted upon frame member 30 adjacent each end oP the
frame member a.s by mounti.ng brackets 36 to be vertically
aligned wi.th strand~ 18c of the chain and with the associated
outer support plate 32. Article supporting cradles 38 are
fixedly mounted on carrier frame me~nber 30 and suitably
conformed -to support an article such as A indica-ted by broken
line in Figures 3 and 4 upon the carrier.
As best seen in Figure 4, support plates 32 and 34
~; are formed with spaced parallel edges 40 and 4Z respectively,
these edges being 3paced from each other by a distance
great0r than the diameter of the rollers of chain 18. As
best seen in Figure 5, when a carrier 28 i8 on the upper run
22 of chain 18, it is supported on the chain by the
engagement of the edges 40 of outer support plates 32 upon
rollers R of the inner strand 18c of the chain. When the
carrier is on the lower run 24 of the chain, it is suspended
in an upside-down posi-tion with the edges 42 of its inner
support plates 34 resting upon the inner strand of the chain.
As best seen in Figures 4 and 5, the length of the s-traight
chain engaging edge 40 of outer support plate 32 is
~; sufficient to span several rollers of chain 18 when on the
upper run so that the carrier 28 is safely supported upon the
chains. The precise length of the straight chain engaging
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edge 40 o:~ outer pla-tes 32 is not cril;:ical, but for practical
purposes ~hould be long enou~h to engage at least three
rollers oP -the cha.in when the carrier is on the upper run;
that is, the length of edge 40 will exceed three times the
chain pitch.
AB can be seen in Figure 4, inner support pla-te 34
is formed with a wheel engaging edge 44 which is in parallel
and spaced apart re:Lation to chain engaging edge 42. A
resiliently surfaced wheel 4~, ~hown in Figures 3 and 5
(preferably comprised o-P a deformable substance such a3
rubber), is mounted for rotation about each of the axes of
end sprockets 12, 14 and posi-tioned thereon for engagement
with the wheel engaging edge 44 oP inner support plate 34.
The rad.ius of wheel 46 exceeds the distance between the
respective sprocket axis aad the wheel engaging edge 44 at
its close~t approach to the sprocket axis during -travel o-
~the carrier 28, as can be seen in Figure 5.
When a carrier 28 is located on either the upper or
lower run o$ the chains 18, moYement of the chains will
normally advance the carrier 28 with the chain by virtue of
the friction between the chain roller~ and the engaged
support plate. However, i-f the carrier 28 is physically
re~trained ~y some external *orce against movement with the
chain along either o-f -these horizontal runs, the chain i9
free to move, relative to the carrier, with the rollers of
strand l~c rolling along the Plat surface 40 (or 42) o* the
engaged support plate. At the opposite ends of the ~lat
chain engaging edge 42 of inner support plate 34, beveled
edge sections 48 may be provided. Beveled edge sections 48
are inclined Prom the ~lat edge section 42 at an included
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:- . -
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ob-tuse angle (-typically but not necessarily abouk 160) Por a
rea~on to be describsd below. Si~ilar bevel~ may be provided
on the outer support plate 32 in order that the inner and
outer support plates may be of the same 3ize and shape to
3implify par-t replacement; however, -the beveled edge
- ~ections, if providedl have a function only on the inner
support plates ~4.
When it is de3ired to accumu]ate article~ conveyed
along the upper run 22 of the conveyor, a stop de~ignated
generally 62 (~igure~ 1 and ~) i9 elevated to engage a ~-top
plate .60 (Figure 3~ on a carrier 28, and the carrier engaged
by the ~top i~ held stationary on the upper run of the chain~
18 which continue to move, the rollers of the chain rolling
; along the straight edges 4U of the outer ~uppor-t plates 32.
-~ Carriers 28 can -thus be accumulated a~ desired.
,` Re~erring now to Figure ~, when a carrier 28 is
located on the lower run 24 of the chain 18, the straight
edge section 42 o~ inner support plate 34 rest~ upon a
; plurality of rollers R to su~pend the carrier in an inverted
po~ition from the lower run of the chain. Again, carriers on
;~ the lower run ~ay either move with the chain or may be
accumulated by the provision of a suitably located stop (no-t
shown).
The pre~ent invention is primarily concerned with
a~suring a controlled driving movement o~ the carrier~ 28 as
they pass around the sprocket~ 12, 14 between the upper and
lower run~ of the chain path.
This can be ~een in Figure ~; when a carrier 28
reaches the end of either the horizontal upper run 22 or the
hori~ontal lower run 24 thu~ reaching the arcuate areas o:f
1~
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the conveyor ad~acent the sprockets 12 and 14, its wheel
engaging edge 44 w:ill come into engagement with the resi]ient
surface of wheel 46. Due to the resiliency of the 3urPace o~
wheel 46, a biasing force will urge inner support plate 34 in
a radial direction outward. This will cause chain engaging
edge 42 to firmly contact at least ~ome of the rollers ~,
such as R3, Rl, ~2 and R4. Hence, undesirable vertical
slippage between inner supE~ort p:Late 42 and chain 18 will be
prevented.
As shown in Figure ~, the beveled edges 4~ of chain
engag~ing edge 42 enhance the engagement of chain engaging
edge 42 with chain 18. However, it is not cr:itical that
bevels 48 be present on chain engaging edge ~2. Chain
engaging edge 42 may e~hibit a variety of shapes, such as a
straight section with rounded corners or a straight section
with square corners, etc.
While one embodiment of the invention has besn
described in detail~ it will be apparent to those skilled in
the art the disclosed embodiment may be modi~ied. Therefore,
the foregoing description is to be considered exemplary
rather than limiting, and the true scope of the invention is
that defined in the ~ollowing claim~.
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