METHOD AND APPARATUS FOR FITTING CARRYING HANDLES ON PACKS OR MULTIPACKS

Abstract

A method for fitting carrying handles to packages includes, prior to receiving a package at a first carrying-handle applicator, drawing off and severing a length of carrying-strap material, retaining the strap's ends, causing the band to guide the carrying strap along the carrying-strap conveying stretch such that the carrying-strap forms a closed loop that extends over a movement path of the packages along the conveyor and that surrounds the movement path on at least three sides, and, when the package reaches a position under the conveying band, securing the to corresponding first and second attachment points on the package, the attachment points being regions facing corresponding first and second sides of the conveyor.

Description

FIELD OF INVENTION

The invention relates to packaging, and in particular, to forming packs of articles.

BACKGROUND

Goods of all kinds are, as a rule, nowadays packed or offered in packages, in order to simplify transport, safeguard the goods themselves against damage or loss, and for the purpose of improved presentation, thereby promoting sales.

Likewise, individually packed goods, such as beverages filled into bottles, are combined to form larger pack groups or multipacks. These are then assembled to form, for example, what are referred to as tray packs. In this situation, for example, six bottles are brought together by way of a paper board base and a shrink wrap film to form a mechanically stable sales unit. The principle is also known of bringing together bottles or other containers in this way to form a packing unit, in that the containers are bonded to one another by the use of at least one adhesive.

In order to increase customer use, many market participants regard it as advantageous if all the pack groups described above are provided with, or can be provided with, a carrying handle.

Hereinafter, for the sake of simplicity, all the packs or packages known to the art, such as bottles, cans, multipacks, etc. are designated as containers.

In the majority of cases in which containers are equipped with a carrying handle, the handle is a carrying strap, which is configured to be self-adhesive on one side, and, as a rule is a plastic strip. While the beginning and end of this carrying strap are pressed by suitable devices onto one side each of the container, and are therefore adhesively bonded to it, the adhesive side of the middle part of this carrying strap has, as a rule, a paper strip bonded to it, in order to prevent a customer's fingers from sticking to the carrying strap, and in order to ensure the configuration of the carrying handle in the form of a loop.

To produce such carrying straps, in the prior art use has been made essentially of two methods. With a first method, these straps are equipped with the paper strips described heretofore during their actual production process, such that these strips need only be cut to length and applied inside the machine that applies the carrying handles from an endless strip-form carrying strap material. A disadvantage of this method is that any change in the configuration of the carrying handle, whether it be the overall length, the length of the adhesive points, or the lands of the carrying loop, incurs the changing of the plastic strip.

With another method, a strip-form carrying strap material is used, which on one side is entirely self-adhesive. Inside the machine that applies the carrying handles, the section of this strap lying between the two desired adhesion points is provided with a paper strip, wherein the adhesion points required at the beginning and end of the carrying strap remain free. By means of this technique, due to the fact that the length of the carrying strap, it becomes possible to adjust the location and length of the paper strip in a simple manner to meet changing requirements. This avoids the necessity of frequent changing of the carrying strap material, which in practice represents a great advantage.

All remarks made in the present specification in connection with the carrying strap material or carrying strap also apply by analogy to the use of carrying strap materials which consist of other materials such as paper or metal, or any desired combinations of these materials.

With regard to the machines or devices that apply the carrying handles, numerous different solution proposals have become known in the past.

With all known devices it is also a disadvantage that a change in the container size as a rule makes necessary an elaborate readjustment of the working height of the device.

Likewise, in practice, it is a significant disadvantage that known devices require a comparatively large spacing interval between the individual containers, as a result of which high container speeds are necessarily incurred. Elaborate mechanical measures are required in order to build up to these high container speeds and then slow down again.

SUMMARY

An object and purpose of the present invention is to provide a method which avoids the disadvantages referred to heretofore, which can be adjusted in a simple manner to even the most widely differing container dimensions, and can apply carrying handles to packs or pack groups with high capacity (number of carrying handles per time unit).

As used herein, the term “packs” refers to packages or containers that are conventionally used in the food industry, and especially also in the beverage industry, and in particular containers such as bottles, cans, and also soft packaging, such as that manufactured from cardboard and/or plastic film and/or metal film, transport containers, such as bottle boxes, etc.

As used herein, the term “pack groups” refers to packs assembled to form groups, such as multipacks of packs of this kind.

As used herein, expressions such as “essentially” or “some” or “approx.” signify deviations from a respective exact value by ±10%, preferably by ±5%, and/or deviations in form of changes which are not of significance to the function.

Further embodiments, advantages, and possible applications of the invention are also derived from the following description of exemplary embodiments and from the figures. In this situation, all the features described and/or graphically represented are in principle the object of the invention, alone or in any desired combination, regardless of their inclusion in the claims or the reference thereto. The contents of the claims are also constituent parts of the description.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in greater detail hereinafter on the basis of the figures, by way of exemplary embodiments. The figures show:

FIGS. 1 and 2 show device according to the invention in a very simplified representation, in a view from above and a side view;

FIGS. 3-5 shows a schematic presentation and in different operational states, a carrying-handle applicator for use with the device from FIG. 1;

FIGS. 6-8 show further embodiments of the carrying-handle applicator for use with the device from FIGS. 1 and 2;

FIGS. 9a-9c show pack groups or multipacks with carrying handles connected at different locations;

FIGS. 10 and 11 show a plural carrying-handle applicators.

DETAILED DESCRIPTION

FIGS. 1 and 2 show a packaging machine 1 that applies handles to pack groups 2. These handles can be carrying loops. The pack groups 2 are multipacks formed from plural packs 3. A typical pack 3 is a container or a bottle. In the embodiment shown, there are twelve packs 3 per pack group 2, with the packs 2 being arranged into a rectangular array having four rows and three columns.

The packs 3 are connected to one another in a suitable manner to form the pack group 2. This can be done by a film that encompasses the packs 3, such as a shrink film. It can also be done by and adhesive that holds the packs 3 to each other.

Referring to FIG. 2, each pack group 3 has a carrying strap 5 that forms a carrying handle 4. The carrying strap 5 is secured with its two ends on opposing sides of the pack group, for example by adhesive bonding, or by welding. In some embodiments, the carrying strap 5 is plastic.

The packaging machine 1 comprises a conveyor 6 on which the pack groups 2 stand upright. The conveyor 6 conveys the pack groups continuously in a conveying direction A.

Along the path of the pack groups 2 is a carrying-handle applicator 7 that applies carrying handles 4 to the pack groups 2. It does so by drawing off a length of carrying strap from a carrying-strap store 5.2 that holds an endless or band-form carrying-strap material 5.1, as shown in FIG. 1. It then severs off a length of the carrying-strap material 5.1 sufficient to form the carrying handle 4, and then connects the two ends of the carrying strap 5 to a pack group 2.

Each pack group has first and second sides 2.1, 2.2 that are oriented along a direction that is parallel to the conveying direction A. The packaging machine 1 attaches a first end of the carrying strap 5 to the first side 2.1 and a second end of the carrying strap 5 to the second side 2.2.

At least at the connection of the carrying handles 4 or the carrying handle ends to the pack group 2, the carrying-handle applicator 7, or a portion thereof, is carried out of a starting position, together with the pack group 2, in the transport direction A. The carrying-handle applicator 7, or the displaced part thereof, moves along only a very short distance, for example a distance of a few millimeters, stretching a spring or elastic material as it does so. After the carrying handle 4 has been connected, the spring or elastic material moves the carrying-handle applicator 7, or the displaced part thereof, back into its starting position before the carrying-handle applicator 7 applies a further carrying handle 2 to the next pack group 2.

FIGS. 3-5 show a first embodiment of a carrying-handle applicator 7a in different operational states.

As shown in FIG. 3, the carrying-handle applicator 7a includes a pivot-arm arrangement 8 having a horizontal middle element 8.1 that is secured to a frame of the carrying-handle applicator 7a. The middle element 8.1 extends along a direction perpendicular to the conveying direction A above the conveyor 6 and above the movement track of the pack groups 2 on the conveyor 6.

The middle element 8.1 extends between first and second joints 9. A first pivot arm 8.2 extends between the first joint 9 and a first retaining-and-pressing element 10. Similarly, a second pivot arm 8.3 extends between the second joint 9 and a second retaining-and-pressing element 10.

Both the first and second pivot arms 8.2, 8.3 pivot around their corresponding joints 9 about a horizontal axis parallel to the conveying direction A. In particular, the first and second pivot arms 8.2, 8.3 pivot between a raised starting position and a transfer position. In the raised starting position, the first and second pivot arms 8.2, 8.3 extend horizontally. In the transfer position, the first and second pivot arms 8.2, 8.3 project downwards from the joints 9.

The carrying-handle applicator 7a further comprises a cutting device 11 disposed between the store 5.2 and the pivot arms 8.3, 8.3.

The mode of operation of the carrying-handle applicator 7a is shown in FIGS. 3-5.

First, with the carrying-handle applicator 7a raised, a drawing device draws off a length of carrying-strap material 5.1 from the carrying-strap store 5.2. The length drawn off corresponds to the length of the carrying strap 5 needed to make a carrying handle 4.

A contact adhesive on one side of the carrying-strap material 5.1 makes the carrying-strap material 5.1 self-adhesive. Its width of which is equal to the width of the carrying strap 5 forming the carrying handle 4.

The drawing device draws off the carrying-strap material 5.1 in such a way that its leading end reaches all the way to the retaining-and-pressing element 10 that is located remotely from the cutting device 11, as shown in FIG. 3. Both retaining-and-pressing elements 10 then hold the carrying-strap material 5.1 at the non-adhesive side thereof. They do so, for example, by vacuum. The cutting device 11 then severs the carrying-strap material 5.1.

With the carrying strap applicator 7a still raised, the two pivot arms 8.2 and 8.3 are then folded downwards, as shown in FIG. 4. In this configuration, the two ends of the carrying strap 5, each of which is still being held by its corresponding retaining-and-pressing element 10, are pre-positioned on opposite ends of a line segment that extends horizontally perpendicular to the conveying direction A. The carrying strap 5 thus stands ready, pre-shaped to form the loop that will ultimately become the carrying handle 4. The carrying strap 5 remains in this raised waiting position outside the movement space of the pack groups 2 until a pack group 2 arrives underneath it.

Once a pack group 2 arrives, the pivot-arm arrangement 8 lowers itself and the first and second retaining-and-pressing elements 10 press the self-adhesive ends of the carrying strap 5 against the pack group 2, as shown in FIG. 5.

The foregoing operations of drawing carrying-strap material 5.1 from the carrying-strap store 5.2, severing the necessary length carrying-strap material 5.1, and pivoting of the pivot arms 8.2 and 8.3 into the transfer position can all take place while the pack group 3 is still making its way toward the carrying-handle applicator 7a. As a result of this, there is essentially no lost time associated with attaching the carry handles 4. This promotes a high throughput for the device as a whole.

FIGS. 6 and 7 show an alternative embodiment of the carrying-handle applicator 7b in which a conveyor band 12 replaces the pivot-arm arrangement. A controlled electric drive 13 rotates the conveyor band 12 in a band-rotation direction B. In this embodiment, the conveyor band 12 draws off the length of the carrying-strap material 5.1 from the carrying-strap store 5.2, and also pre-positions and pre-shapes the carrying strap 5 into a loop that forms the carrying handle 4.

In some embodiments, the conveyor band 12 is a vacuum band. In such embodiments, the conveyor band 12 has openings that are subjected to a vacuum. A guide element having deflectors 14 forms the conveyor band 12 into a closed loop that lies in a vertical plane that is perpendicular to the conveying direction A. The closed loop of the conveyor band 12 has first and second loop sections 12.1, 12.2 extending vertically along corresponding first and second longitudinal sides of the conveyor 6. A third loop section 12.3 extending above the conveyor 6, and hence above the movement space of the pack groups 2, connects the first and second loop sections 12.1, 12.2. The first, second, and third loop sections 12.1, 12.2, 12.3 of the conveyor band 12 thus surround three sides of the movement space of the pack groups 2.

The circulating conveyor band 12 prepares the carrying handle 4 by having the second loop section 12.2 take up an end of the carry-strap material 5.1. The carry-strap material 5.1 follows an inner loop length of the second loop section 12.2 facing the movement path of the pack groups 2. The second loop section 12.2 and the third loop section 12.3 eventually bring the carry-strap material 5.1 to a pressing element 15 at the first loop section 12.1.

The cutting device 11 cuts the carrying-strap material 5.1 to the proper length while the conveyor band 12 is no longer circulating.

In greater detail, controlled movement of the conveyor band 12 moves the carrying-strap material 5.1 until the severance point is at the cutting device 11. At this point, the conveyor band 12 stops. This permits the cutting device 11 to simply and reliably cut the carrying-strap material 5.1 to form a carrying strap 5 having the desired length.

Once the cutting device 11 has cut the carrying strap 5 to its proper length, the conveyor band 12 continues its movement until both ends of the pre-formed carrying handle 4 have been brought to the respective pressing elements. 15. At this point, the carrying handle 4 is ready to be secured.

In some embodiments, the cutting device 11 cuts while the conveyor band 12 is moving. In other embodiments, the conveyor band 12 changes its movement direction for the purpose of cutting to length.

The conveyor band 12 holds the carrying strap 5 by its non-adhesive side. When the self-adhesive ends of the carrying strap 5 are pressed against the pack group 2, only the pressing elements 15 actually move with the pack group 2. They do so only over the short distance referred to heretofore. This is possible in part because of the conveyor band's elasticity.

At about the same time that the pressing elements 15 press the carrying handle 4 against the pack group 3, the vacuum holding these ends is at least partially switched off. This allows the carrying handle 4 to be taken along with the pack group 2 to which it is has been secured.

The length or size of the loop formed by the carrying strap 5, and therefore of the carrying handle 4, is determined by the carrying-strap conveying-path, which the conveyor band 12 forms between the two pressing elements 15. By changing the lengths of the first, second, and third loop sections 12.1, 12.2, 12.3, it is possible to change the length of the carrying handle 4 and in particular, to adjust it to the size of the pack group 2. This adjustment can be carried out by adjusting the deflectors 14 or the deflectors' bearings. Moreover, the adjustment of the length of the carrying strap 5 is also possible by replacing part segments of the carrying-strap conveying-stretch formed by the conveyor band 12.

FIG. 8 shows yet another embodiment of a carrying-handle applicator 7c. This third carrying-handle applicator 7c has both a first conveyor band 12 and a second conveyor band 12a, both of which form a separate first and second closed loops. First and second drives 13, 13a drive the corresponding first and second conveyor bands 12, 12a to circulate. Both the first and second conveyor bands 12, 12a are vacuum bands.

The first loop, which the first conveyor band 12a forms, includes the extension of the first loop section 12.1 which with this embodiment is configured as shortened. In order to form the carrying handle 4, the front end of the strip-form carrying-strap material 5.1 is again taken up at the inner loop length of the second loop section 12.2, with the first and second conveyor bands 12, 12a circulating, and initially moved with the first conveyor band 12 and then with the second conveyor band 12a. After the severing of the carrying strap 5 from the carrying-strap material 5.1 by the cutting device 11, the two ends of the carrying strap 5 are located at pressing elements 15 on both sides of the conveyor 6 or, respectively, of the movement path of the pack groups 2 with the carrying handle 4 prepared, which then, when a packing group 2 reaches the carrying-handle applicator 7c, is secured to the packing group 2 by pressing of the carrying handle's ends.

An advantage of the third carrying-handle applicator 7c is that, by using first and second conveyor bands 12, 12a, the length of the carrying strap 5, and therefore the size of the carrying handle 4, is no longer dependent on the length of the carrying-strap conveying-stretch of the conveyor band 12. Rather, due to the separate actuation of the first and second conveyor bands 12, 12a, an adjustment is carried out of the length of the carrying-strap conveying-path between the two pressing elements.

A particular advantage of the carrying-handle applicator 7c is that the two ends of the carrying handle 4 can be moved and positioned independently of each other. This makes it possible to adjust the height at which the carrying handle 4 attaches to the packing group 2.

It has been assumed heretofore that the connecting of the carrying strap ends to the respective packing group 2 takes place by pressing, which is subject to the precondition that the carrying strap 5 be configured to be self-adhering at least at its two ends. However, this is not the only way to attach the carrying handle 4. Other types of connection of the respective carrying handle 4 to the pack groups 2 are possible, for example connecting by an application of adhesive or glue, which is applied onto the carrying handle ends only shortly before the pressing or pressure imposition to the respective pack group 2, or by welding, for example with all-round packing of the respective pack group 2, for example by ultrasonic welding, etc.

It has been assumed heretofore that the pressing or connecting of the two ends of the carrying handle 4 to the respective pack group 2 takes place simultaneously or essentially simultaneously. However, it is possible to press at different times. With the pack group 2 still moving, the result can be seen in FIGS. 9a-9c.

FIGS. 9a and 9b show pack groups 2 with carrying handles 4 that have been secured so that the two points of attachment on opposing sides 2.1, 2.2 of the pack group 2 are offset from each other. This can be achieved by, after having secured one end of the carrying handle 4 and before securing of the other end of the carrying handle 4, causing relative movement between the carrying-handle applicator 7, 7a-7c, and the pack group 2.

FIGS. 10 and 11 show a packaging machine 1a that differs from the packaging machine 1 essentially only in that, related to the conveying direction A, a plurality of carrying-handle applicators are provided for, with one following the other. These collectively form one applicator unit 16. The carrying-handle applicators 7 comprise in detail a configuration suitable for the method according to the invention, for example corresponding to the carrying-handle applicators 7a-7c.

With the packaging machine 1a, it is possible, for example, with higher capacity to attach more than one carrying handle 4 to a pack group 2. For example, it may be especially useful to have two carrying handles 4 that are either parallel to each other or that cross-over one another.

With plural carrying-handle applicators 7, it becomes possible to actuate these carrying-handle applicators 7 in such a way that each carrying-handle applicator 7 provides only a part of the pack group 2 with at least one carrying handle 4, but, that, by way of the carrying-handle applicators 7 in their entirety, all the pack groups 2 are provided in each case with a carrying handle 4. In such cases, the individual carrying-handle applicators 7 work in an offset manner. This substantially increases the capacity of the packaging machine 1a.

All embodiments have in common that the securing of the carrying handle ends or the ends of the carrying straps 5 to the pack groups 2 or to the individual packs 3 takes place, in relation to the conveying direction A, from the side or perpendicular or essentially perpendicular to the conveying direction A, and that the carrying handle 4 is already completely pre-formed before its connection to a pack 3 or a pack group 2, and is provided pre-positioned in a waiting position.

It is also possible for each carrying handle 4 to consist of two parts that are connected to each another at a suitable time. This connection then takes place before, after, or during the positioning or connection of the carrying handle ends to the pack group 2 or the pack 3. It is also significant here that all the connection or adhesion points of the parts of the carrying handle 4 or of the carrying handle 4 already produced from the parts are positioned in a correct arrangement in the carrying-strap store 5.2, and then connected in a controlled manner to the pack group 2 or the pack 3.

It is also possible for the pack 3 or pack group 2, before the application of the carrying handle 4, to be rotated about its vertical axis in such a way that, at the application of the carrying handle 4, its orientation relative to the conveying direction has changed. Such an orientation, for example, allows for the carrying handle(s) to be applied to the pack 3 or pack group 2 at a changed angle setting, such as is represented, for example, in FIG. 9c. By way of this arrangement it is possible to easily apply a carrying handle 4 diagonally across the pack group 2.

In this connection it is understood, in greater detail, that the direction of effect of the force of the secured carrying handle 4 during carrying extends essentially directly in the direction of the securing point located opposite the other end of the carrying handle 4. This substantially reduces loading of the pack 3 or pack group 2 with undesirable transverse, longitudinal, and flexural forces.

It has been assumed that the pack groups 2 move continuously with the conveyor 6. In principle, it is also possible for the conveyor 6 to move intermittently, in brief pulses of movement. In these embodiments, the connection of the prepared carrying handle 4 to a pack 2 can take place during the pauses between movements.

It has been assumed that the conveyor band 12, 12a, if configured as a vacuum band, is subjected along its entire path to a vacuum. However, in some embodiments, there are stretches of the conveyor band's path that are free of vacuum. In these embodiments, the distribution of vacuum along the path need not be constant. For example, a particular stretch of the conveyor band's path may be free of vacuum at some times but not at other times.

The invention has been described heretofore on the basis of selected embodiments. It is understood that numerous modifications are possible without departing from the basic inventive idea on which the invention is based.

Having described the invention, and a preferred embodiment thereof, what is claimed as new, and secured by letters patent is:

Claims

1-13. (canceled)

14. A method for fitting carrying handles to packages selected from the group consisting of pack groups and packs, said packages being arranged on a conveyor that moves said packages in a conveying direction towards a first carrying-handle applicator, said method comprising, prior to receiving a package at a first carrying-handle applicator that comprises pressing elements for securing a carrying strap against said package, and a conveying band that forms a carrying-strap conveying-stretch for guiding said carrying-strap during formation of a carrying handle, drawing off a length of carrying-strap material, severing said carrying-strap material, thereby forming a carrying strap extending between first and second ends thereof, said first and second ends being separated by said length, retaining said first and second ends, causing said conveying band to guide said carrying strap along said carrying-strap conveying stretch such that said carrying-strap forms a closed loop that extends over a movement path of said packages along said conveyor and that surrounds said movement path on at least three sides thereof, and when said package reaches a position under said conveying band, securing said first and second ends of said carrying-strap to corresponding first and second attachment points on said package, said attachment points being at first and second regions of said package, said first and second regions facing corresponding first and second sides of said conveyor.

15. The method of claim 14, wherein securing said first and second ends comprises using said pressing elements to apply corresponding first and second forces in directions transverse to said conveying direction.

16. The method of claim 14, further comprising securing two carrying strap parts to said package by said first end and connecting said strap parts to each other by said second end.

17. The method of claim 14, further comprising, before connecting said carrying handle to said package, pre-forming said carrying strap into a carrying loop for forming said carrying handle and pre-positioning said carrying loop with said first and second ends of said carrying strap disposed opposite one another.

18. The method of claim 17, further comprising retaining said pre-formed carrying loop in a waiting position until at least one of said first and second ends has been secured to said package.

19. The method of claim 14, wherein securing occurs without relative movement between said first carrying-handle applicator and said package while said package is being conveyed.

20. The method of claim 14, wherein securing occurs without relative movement between said pressing elements and said package while said package is being conveyed.

21. The method of claim 14, wherein securing said first end occurs simultaneously with securing said second end.

22. The method of claim 14, wherein securing said first and second ends comprises securing said first end, and, after having secured said first end, securing said second end, thereby causing a temporal offset between securing said first end and securing said second end.

23. The method of claim 14, wherein securing comprises pressing said ends against said package to cause a contact adhesive on said carrying strap to engage said package.

24. The method of claim 14, wherein securing comprises welding said ends to said package.

25. The method of claim 14, wherein securing comprises illuminating said ends and said package with ultrasonic radiation.

26. The method of claim 14, wherein causing a package to move along a conveying direction comprises causing said package to engage in pulsatile movement, wherein said pulsatile movement comprises a movement interval and a standing interval, wherein during said movement interval said package moves, wherein during said standing interval said package is standing still, and wherein securing said first and second ends occurs during said standing interval.

27. The method of claim 14, wherein causing a package to move along a conveying direction comprises causing said package to move continuously, and wherein securing said first and second ends occurs while said package is moving.

28. The method of claim 14, further comprising using a second carrying-handle applicator that has the same structure and operation as said first carrying-handle applicator, wherein each of said first and second carrying-handle applicators applies a carrying handle to only part of said package, wherein said first and second carrying-handle applicators cooperate to apply a carrying handle to said package.

29. An apparatus for fitting carrying handles to a package selected from the group consisting of a pack group and a pack, said apparatus comprising a carrying-handle applicator disposed along a conveyor to receive packages that are conveyed by said conveyor, said carrying-handle applicator being configured to, while a package is approaching said carrying-handle applicator, draw off a length of carrying-strap material and to sever said carrying-strap material, thereby forming a carrying strap extending between first and second ends thereof, said first and second ends being retained by said carrying-handle applicator and separated from each other by said length, wherein said first carrying-handle applicator comprises pressing elements, and a first conveying band, wherein said first conveying band forms a closed loop, and a carrying-strap conveying stretch for guiding said carrying-strap such that said carrying-strap forms a closed loop that extends over a movement path of said packages along said conveyor and that surrounds said movement path on at least three sides, and wherein, when said conveyor conveys said package to a position under said conveying band, said pressing elements secure said first and second ends to corresponding first and second attachment points on said package, said first and second attachment points being disposed at first and second regions of said package that face corresponding first and second sides of said conveyor.

30. The apparatus of claim 29, wherein said carrying-strap conveyor comprises a second conveyor band having a structure that is identical to said first conveyor band, and wherein said second conveyor band forms a second closed loop.