CA1217162A

CA1217162A - Conveyor

Info

Publication number: CA1217162A
Application number: CA000423023A
Authority: CA
Inventors: Barry Robertson
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-03-07
Filing date: 1983-03-07
Publication date: 1987-01-27

Abstract

ABSTRACT OF THE DISCLOSURE

A conveyor suitable for carrying food trays has a channel shaped track with horizontal supporting surfaces on opposite sides of the track. A conveyor chain supported for movement longitudinally of the track has a series of supporting slats connected thereto and extending laterally therefrom. Outer portions of the slats are supported by the supporting surfaces. Connecting members that are separable from their respective slats, detachably connect the slats to the chain. 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. Higher level slats and lower level slats are arranged in alternating fashion along a chain. The top of each lower level slat is located slightly below the bottom of the adjacent higher level slat.

Description

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.

, 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 ~z~

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 r~r~9~

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.

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 ,.. .. ..

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 . ,, , ~L7~

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 lZl~Z

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.

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.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A conveyor comprising a generally channel shaped track; supporting means on opposite sides of said track; a conveyor chain supported for movement longitudinally of said channel shaped track; a series of supporting slats connected to said chain and extending laterally therefrom, said slats being supported by said supporting means; and connecting members for detachably connecting said slats to said chain, said members being separable from their respective slats, wherein 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 said upper section and wherein each connecting member is open at the bottom in order to receive said chain between said side sections.

2. A conveyor according to claim 1 wherein said series of slats comprises higher level slats and lower level slats which are arranged in alternating fashion along said chain and the top of each lower level slat is located slightly below the plane defined by the bottom of the adjacent higher level slat.

3. A conveyor according to claim 1 wherein the upper section of each connecting member is connected to the bottom of its respective slat by a wedge-shaped, tongue and groove connection with said tongue tapering inwardly in the direction of conveyor movement.

4. A conveyor according to claim 1, 2 or 3 wherein said slats and connecting members are constructed from plastics material.

5. A conveyor according to claim 1, 2 or 3 wherein a lateral flange extends outwardly away from the chain from the bottom of each of said side sections.

6. A conveyor according to claim 1 wherein said conveyor has at least one horizontal corner and friction reducing means for assisting movement of said chain and slats around the one or each horizontal corner, said friction reducing means engaging the outer surfaces of side sections of said connecting members and including a set of wheels or pulleys mounted on vertical axes.

7. A conveyor according to claim 6 wherein said friction reducing means includes a grooved or toothed belt mounted on a set of pulleys and each side section of each connecting member has a tooth member projecting outwardly from its outer surface, said belt engaging the teeth members located closer to the inside of the horizontal corner as said teeth members move around said corner.

8. A conveyor suitable for transporting food trays comprising a track having support means on opposite sides of a central section; a conveyor chain supported for movement along said central section of said track; and first and second sets of supporting slats connected to said chain and extending laterally therefrom, the slats of one set alternating with the slats of the other set, the bottoms of said first set of slats being supported by said support means, both sets of slats having generally flat tops and bottoms; the top of each slat in said first set is located slightly below the plane defined by the bottom of the adjacent slats of said second set.

9. A conveyor according to claim 8 wherein each slat is connected to said chain by a connecting member having an upper section disposed parallel to the slat and two, spaced-apart, downwardly extending side sections, said side sections have holes to receive the ends of pins projecting from the sides of said chain.

10. A conveyor according to claim 9 wherein said upper section of each connecting member has a wedge-shaped tongue projecting from the top thereof and the bottom of each slat has a wedge-shaped groove formed thereon and adapted to receive said tongue.

11. A conveyor according to claim 8, 9 or 10 wherein, when the chain and slats are traversing a straight path, the front and rear edges of each slat of said second set extend over rear and front edges of adjacent slats of said first set.

12. A conveyor according to claim 9 wherein a lateral flange extends outwardly away from said chain from the bottom of each of said side sections.

13. A conveyor according to claim 9 or 10 wherein said connecting members are made from a flexible plastic and said upper sections thereof can be flexed for connecting said connecting members to said chain.

14. A conveyor according to claim 9 or 10 wherein said slats are made from a harder plastic than said connecting members.

15. A conveyor according to claim 10 wherein said tongue and said groove taper inwardly in the direction of travel of said conveyor.

16. A conveyor according to claim 8 wherein said conveyor has at least one horizontal corner and friction reducing means for assisting movement of said chain and slats around the one or each horizontal corner, said friction reducing means engaging connecting members, that join said slats to said chain, and including a set of wheels or pulleys mounted on vertical axes.

17. A conveyor according to claim 16 wherein said friction reducing means includes a grooved or toothed belt mounted on a set of pulleys and each connecting member has at least one tooth member projecting outwardly from a vertical side thereof, said belt engaging the teeth members as the latter move around said corner.