Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to an improved conveyor
and in particular a conveyor capable of following a curved
or tortuous path or track.
Various conveyors are known in the conveying art
for transporting articles or objec~s such as food trays.
It is preferable that such conveyors be capable of
travelling a curved path as well as a straight path. In
this way the conveyor can be installed in a variety of
locations having various layouts~ For some purposes it is
also important that the conveying surface be an unbroken
surface, that is one without gaps~ at all times, even when
the conveyor follows a curved path. The elimination of
gaps avoids the possibility of an object falling through
the gap to a location where it could cause damage to the
conveyor or could be damaged itself. For some applications
it is also important that the conveyor be capable of being
kept clean and sanitary either by regular washings or by a
continuous washing system. A conveyor that can be easily
kept clean is particularly important in the handliny of
food.
One type of conveyor belt suitable for handling
food trays that is in current use is that taught and
illustrated by Canadian Patent No. 904,780 issued July ll,
l972 to R.E. Cabak. The conveyor taught by this patent
specification employs a channel-shaped track having flat,
horizontal supporting surfaces on opposite sides thereof.
A side bow conveyor chain of conventional construction
travels longitudinally down the center of the track.
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Mounted to this chain are a series of overlapping plastic
plates, each of which has two downwardly extending flanges
on opposite sides of its center. Frusto-conical rollers
are mounted on the outside of these flanges on vertical
pivot pins. These rollers engage the sides of the track
and reduce friction as the chain and slats negotiate a
horizontal curveO
Canadian Patent No. 1,007,188 issued March 22,
1977 to U. Henrekson teaches a conveyor construction which
permits the conveyor to deflect or turn in several
directions. The conveyor employs a single cable to which
are connected U-shaped members that are attachable to
plates used to form a conveying surface. Pins project
transversely from opposite sides of the U-shaped members.
These pins engage double gears that are used to pull the
conveyor along. The slats or plates forming the conveying
surface are connected to the U-shaped members by means of a
dovetail connecting mechanism provided at the top of the
U-shaped member and on the bottom of each slat.
Canadian Patent No. 1,018,092 issued September
27, 1977 to Garvey Corporation teaches an endless chain
conveyor wherein the chain comprises two kinds of links.
The first type is a conventional flat plate element
containing bearing holes and the second type is a special
yoke link that is made of metal. Each yoke link is
generally channel shaped, the channel being inverted in the
operative run of the chain. Each yoke link has a top web
and side walls 44 extending downwardly from the side edges
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of the top web. These yoke links also have spaced holes
located in the side walls. Mounted on the outside of each
side wall is a wear pad made of anti-friction material. A
top plate, which provides a supporting surface for the
articles to be conveyed, is mounted on the top of each yoke
link.
A difficulty with some of the known conveyor
systems such as that taught by Canadian Patent No. 304,780
is that it is not easy to replace broken or worn conveyor
slats, particularly for a person who has not been trained
in the repair and maintenance of such units. Although the
irdividual slats may be detachable from the chain which
pulls the slats along, it is often difficult for one to
detach an old slat or attach a new slat. In the case of
the conveyor taught by the aforesaid patent, it is
necessary to bend the ends of the slat sufficiently so that
the downwardly extending flanges will be separated enough
that the pins of the conveyor chain can be pulled from the
holes in the flanges. When attaching a new slat9 it is
necessary to force the pins of the chain between the
flanges on the slat, an operation which may require
considerable strength.
Another difficulty with the conveyor system
taught in Canadian Patent No. 904,780 is that each slat
must be provided with frusto-conical rollers mounted on
pivot pins and these rollers and the support therefor add
considerably to the expense of the system. Thus conveyors
which can operate without the use of such rollers have a
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price advantage over the aforementioned system.
Furthermore in order to permit the system of Canadian
Patent No. 904,780 to include a horizontal curve in the
path of the conveyor, the upper surface and lower surface
S of each slat is formed with two levels, with the lower
level being formed adjacent the leading edge of the slat.
This not only permits the slats to form an unbroken
convey;ng surface at all times but it permits adjacent
slats to overlap as these slats are being pulled around a
horizontal curve.
The present invention prov;des a conveyor that is
suitable for transporting articles such as food trays and
that permits the slats that form the conveying surface to
be easily repaired or replaced. A simple and inexpensive
means is provided to connect each slat to a separate
connecting member which in turn is connected to the
conveyor chain. According to another aspect of the
invention disclosed herein, the con~eyor may employ slats
which have generally flat tops and flat bottoms and yet the
conveyor is capable of following a hor;zontal curve.
According to one aspect of the present invention
a conveyor comprises a generally channel shaped track,
supporting means on opposite sides of the track, and a
conveyor chain supported for movement longitudinally of the
channel shaped track. A series of supporting slats is
connected to the chain and extend laterally there-from.
These slats are supported by the supporting medns.
Connecting members detachdbly connect the slats to the
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chain and are separable from their respective slats. Each
connecting member has an upper section to which a
respective slat is connected and two side sections
extending downwardly from the side edges of the upper
section. Each connecting member is open at the bottom in
order to receive the chain between the side sections
According to another aspect of the present
invention, a conveyor suitable for transporting food trays
comprises a track having support means on opposite sides of
a central sec~ion, a conveyor chain supported for movement
along the central section of the track, and first and
second sets of supporting slats connected to the chain and
extending laterally therefrom. The slats of one set
alternate with the slats of the other set. The bottoms of
the first set of slats is supported by the support means.
Both sets of slats have generally flat tops and bottoms.
The top of each slat in the first set is located slightly
below the plane defined by the bottom of ~he adjacent slats
of the second set.
Preferably the upper section of each connecting
member is connected to the bottom of its respective slat by
a wedge-shaped tongue and groove connection wherein the
tongue tapers inwardly in the direction of sonveyor
; movement, In a particularly preferred embodiment the slats
and connecting members are constructed from plastics
material and thus can be cleaned regularly without fear of
corrosion.
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Other features and advantages will be apparent
from the follo~ing detailed description of a preferr2d
embodiment, taken in conjunction with the accompanying
drawings.
In the drawings,
Figure l is a plan view showing a portion of a
conveyor constructed in accordance with the present
invention;
Figure 2 is a sectional elevation taken along the
l;ne II-II of Figure li
Figure 3 is a perspective view showing a single
slat in dashed lines, a connecting member for connecting
the slat to the~ conveyor chain, and a section of the chain,
which view shows how these parts fit together;
Figure 4 is a rear elevation of the combination
comprising a conveyor slat and a connecting member;
Figure 5 is a rear elevation illustrating another
form of conveyor slat;
Figure 6 is a side elevation showing several
slats connected to a sect;on of conveyor chain and
illustrating how the slats overlap one another;
Figure 7 is a top view showing how the conveyor
chain is guided by a belt and pulley arrangement around a
horizontal corner, the slats having been removed from the
connecting members for ;llustration purposes; and
Figure 8 is a sectional ele~at-;on taken along the
line VIII-VIIS of Figure 7.
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A conveyor suitable for conveying food trays or
other relatively 1arge articles is shown in part in Figure
1. The moving surface of the conveyor is formed with a
series of supporting slats or plates 12 and 14 which are
connected to a standard stainless steel side-bow chain 16
which can best be seen from Figures 3 and 6. The chain is
supported for movement longitudinally of a generally
channel shaped track 18. The track 18 is formed in an
elongate transpor~ table 20 having side portions extending
along both sides of the tracku The table including the
track 18 is preferably constructed from stainless steel,
particularly if the conveyor will be subiect to ~requent
cleanings w~th water. It will be noted from Figure 2 that
the track includes a lower web port;on 22 and vertical
sides 24~ Extending along the inside surface of each side
24 is a wear strip 26 of L-shaped cross-section.
Preferably these wear strips are made from polyethylene and
they extend the complete length of the upper run of the
conveyor. The horizontal legs of these wear strips form
supporking means for the slats 14. In other words the
bottom surfaces of the slats 14 engage and slide along the
top surfaces of these wear strips.
The s-ide-bow conveyor chain 16 is made with a
series of links, each of which includes a pair of parallel
side plates 28. Each pair of l;nks is connected by a pair
of sleeves (not shown) which are encircled by rollers`30
that are free to rotate about the sleeves. Adjacent links
are connected by a pair of parallel connecting plates 32
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which are connected by pins 34 that extend through the
sleeves. The pins 34 are somewhat smaller in diameter than
the inner diameter of the sleeves so that the pins 34 may
extend angularly to the axis of the sleeves when the
conveyor is travelling around a curve. The pins 34 support
the plates 32 spaced apart a distance greater than the
distance between the outer surfaces of the link plates 28
so that the connecting plates 32 will not bind against the
plates 28. The structure of the chain shown in the
drawings is not novel but is illustrated to indicate the
preferred type of chain used to permit the conveyor to bend
around curves.
The slats 12 and 14 are each connected to the
chain 16 by means of a connecting member 36. The
connecting members permit the slats to be connected to and
disconnected from the chain quickly and easily as explained
hereinafter. They are preferably constructed from a
suitable plastic such as ABS plastic and thus they will not
corrode even after repeated washings. Each connecting
member has an upper section 38 to which a slat 12 or 14 ;s
connected and two side sections 40 that extend downwardly
from the side edges of the upper section 38. Each side
section has two holes 42 to accommodate the ends of the
pins 34 of the chain. Each connecting member 36 is open at
the bottom end of the s;de sect;ons in order to perm;t the
cha;n 16 to be rece;ved between the side sectionsO A
lateral flange 44 extends perpendicularly outwardly from
the bottom of each side sect;on 40. The flanges 44 help to
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support the chain on the web 22 of the track. In a
horizontal curve, as shown in Figure 8, the flanges 44 on
the radially outer side of the chain extend under the
bottom of the wear strip 26. In this way the chain and
slats are held on the track and the chain cannot come out
of the track in a curve or bend which is a common and
dangerous occurrence with slat belts that do not use a
retaining means in a curve. It will also be appreciated
that the flanges 44 help to center the chain in the track
18. Integrally formed on the outer surface of each side
section 40 is a tooth member 46 which may have a
-~ semi-circular horizontal cross-section. In the preferred
embodiment shown, this tooth member is located midway
between the front and rear ends of the connecting member.
The purposes of these teeth members is to provide a means
for positive engagement between the connecting members and
a notched or toothed belt provided on the corners of the
conveyor to reduce friction. The operation of this belt
will be described hereinafter in conjunction with Figure
7.
The upper section 38 of each connecting member
has a wedge-shaped tongue 48 projecting from the top
thereof. The tongue, which is in the form of a dovetail
extends from the front to the back of the connecting member
and tapers inwardly in the direction of travel of the
conveyor. The direction of travel is indicated by the
arrow A in Flgure l. The tongue is adapted to snugly mate
with a dovetail groove 50 formed on the bottom of each
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slat. The groove 50 is wedge-shaped, that is it tapers
inwardly in the direction of travel. The groove is formed
by separate lower portions 52 and 54 in the slat 14 (see
Figure 4) and by unitary lower portion 56 in each slat 12
(see Figure 5). In addition to the tongue 48 and the
groove 50 used to connect the member 48 to its respective
slat, there are two locking tabs 58 formed on the bottom
surfaces of the portions 52 and 54 and the portion 56.
These locking tabs engage one side of the top end of the
aforementioned teeth members 46 as can be seen from Figure
6. As each locking tab ;s required to pass over the top of
its respective tooth member 46 as the tongue 48 is shoved
fully into the groove 50, a locking or snap engagement is
formed between the connecting member and the slat~
The difference in the construction of the slats
12 and 14 will now be explained in greater detail with
reference to Figures 4 to 63 As can be seen from a
comparison of Figures 4 and 5, the total height of the
lower portion 56 is greater than the height of portions 52
and 54. The difference in height is equal to the depth of
the central section 60 of the lower portion 560 Because of
the difference in height of the lower portions, two sets of
supporting slats are provided. The slats 12 form higher
leve! slats while the slats 14 form lower level slats and
the slats of the two sets are arranged in alternating
fashion along the chain. Thus the top of each lower level
slat 14 is located slightly below the bottom of the
adjacent higher level slat 12. In this way when the chain
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and slats move around a horizontally disposed corner,
adjacent slats can shift so that the end portions on the
inside of the curve overlap more than they do when the
slats are being pulled along a straight section of the
S conveyor. The use of slats of differing heights permits
all slats to have generally flat ~ops and, except for the
lower portions 52, 54 and 56, generally flat bottoms. Thus
the construction. of the slats is quite simple, which
contributes to the low cost of this conveyor system.
Preferably these slats 12 and 14 are made ~rom a tough~
high quality plastic having a hard, high gloss,
self-protecting finish, since it ;s not a requirement that
the slat be capable of back-bending or flexing so that it
can be mounted to the chain. With the present invention it
is only necessary to bend the side sections of the
connecting member 36 outwardly in the manner shown in
Figure 3. In this Figure the arrows B indicate how the
side portions can be pulled apart in order to permit the
chain to be pushed into the space between the side
sections. A~ter the ends of the pins 34 have slipped into
the holes 42, the connecting member returns to its normal
shape (see Figure 4 for example). Outward flexing of the
side sections 40 is assisted by a V-groove 62 which extends
down the center of the upper section 38 from the front to
2~ the back~ The groove forms a type of hinge and counteracts
the efFect of the increased thickness of the upper section
in the region of the tongue 4~.
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The present conveyor can be constructed so that
it is capable of following a hori~ontal curve, that is a
curve lying in a plane parallel to that of the conveying
surface formed by the slats. Preferably means are provided
for reducing the friction between the track and ~he moving
portion of the conveyor in the region of each horizontal
curve. One mechanism for reducing friction is illustrated
in Figures 7 and 8 of the drawings. This mechanism is
commonly called a "live" corner and it is a well kno~n
mechan;sm in the conveying art for reducing drag caused by
friction. The mechanism comprises friction reducing means
64 which may include a set of relatively small pulleys or
wheels 66, two larger pulleys 67 and 69, and a grooved belt
72. The pulleys or wheels can be constructed in a similar
fashion, except -for the respective sizes. One of the
smaller pulleys 66 is illustrated in cross-section in
Figure 8. The pulley can be made of a suitable plastic
material, A stationary vertical shaft extends upwardly
through the center of the pulley. The shaft 74 can be held
in place by screws threaded into the top and bottom ends of
the shaft. The upper screw 76 extends through a hole in a
support ar~ 78 that is firmly attached in any suitable
manner to the table 20. The bottom screw 80 extends
through a hole in the web 22. A ball bearing 82 is
arranged between the pulley 66 and the shaft. This ball
bearing res~s on a plastic thrust bearing 84 that extends
around the bottom of the shaft. The track 18 can be
widened, if necessary, in the region of the curve to
accommodate the pulleys as illustrated in Figure 7. A
curved wear strip 26 extends around the outside of the
curve. If desired a curved wear strip 86 can be arranged
on the inside of the curve to help in the support of the
slats and to keep them flat as they are pulled around the
curve. In many conveyor applicat;ons, it is desirable to
provide the table 20 with an upstanding edge or rim ~8 to
prevent objects from falling off of the conveyor.
Extending along the belt 72 and spaced equal
distances apar~ are grooves or notches 90. These grooves
are preferably spaced apart the same distance as adjacent
teeth members 46. If desired the grooves can be closer
together than those illustrated in Figure 7. In fact the
grooves can be spaced closely adjacent one another so that
teeth are formed on the outer surface of the belt~ With
such a belt the teeth members 46 will readily find
cooperating grooves in the belt as they move around the
curve.
In place of the belt and pulley arrangement shown
in Figures 7 and 8, the "live" corner could be provided
simply by a serles of wheels adapted to engage the side of
the connecting members directly. These wheels could be
arranged and mounted in the same manner as ~he pulleys 66
to 69 shown in F;gure 7.
The features and advantages of the preferred
conveyor constructed as described herein will be read;ly
apparent from the above description. The conveyor is
capable of turning a corner located in a plane parallel to
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the slats. In one particular preferred embodiment, the
conveyor is capable of turning a corner on a 24 inch
~610 mm) center-line radius. Moreover even in these
horizontal corners, the slats of the conveyor overlap at
all times so that gaps in the conveying surface are
eliminated. The conveyor is very strong and therefore
quite reliable. In one preferred embodiment the steel
chain is a number 60 stainless steel chain having a tensile
strength of 6,100 pounds.
Because the slats need not be bent in order to be
attached to the conveying chain, the slats will not be
broken or weakened by the attachment processO Moresver the
connector and the slat can be attached in a very
straightforward manner and therefore even unskilled
personnel can make repairs to the conveyor.
Another important advantage of the present system
is that only one half the "usual slat" ~the term slat here
referring to the slat 12 or 14 together with the
accompanying connecting member) can be replaced at one
time. ~epending on how the blade portion and the connector
are constructed and in particular on what materials are
used, the life of the blade may be as much as three times
that of the connector. Thus the repdir and maintenance
costs of the present sytem can be kept low by merely
replacing the connector rather than the entire
blade-connectsr combination when the connector has worn out
or been broken.
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The remainder of the conveyor system can be
constructed with the use of standard conveyor equipment and
in a conventional fashion. It will be appreciated by chose
skilled in the art that the chain 16 is engaged by a drive
sprocket which moves the endless chain along upper and
lower flights. If desired the return side of the conveyor
can be constructed using a "monorail" system having support
surfaces made from low-friction material on which the
flanges 44 of the connecting members 36 travel.
It will be appreciated by those skilled in the
art that various modifications and changes can be made in
the construction of the conveyor system described herein
without departing from the spirit and scope of the present
invention. All such modifications and changes which fall
within the scope of the following claims form part of this
invention.
