WO2010142317A1

WO2010142317A1 - Method and device for grouping articles

Info

Publication number: WO2010142317A1
Application number: PCT/EP2009/057031
Authority: WO
Inventors: Linus Bokesand; Tommy Karlsson; Hans ÖSTERGREN
Original assignee: Flexlink Components Ab
Priority date: 2009-06-08
Filing date: 2009-06-08
Publication date: 2010-12-16

Abstract

The present invention relates to a method and arrangement for controlling a flow of units (23) from at least one incoming track (16) to at least one outgoing track (19). The method comprises the steps of : -The incoming track (16) feeds the flow of units (23) at a first speed towards a diverter track (20) comprising a support structure (21) on which said received units rest. -The diverter track (20) further comprises a holding device (18) which holds a unit (24) and feeds it at a second speed being higher than the first speed.10 -The holding device (18) controls the second speed so that it deviates from the speed of the rest of the units (25) resting on said structure, such that a plurality of said received units are brought together and forms a group of units (26) which is fed to the outgoing track (19).

Description

METHOD AND DEVICE FOR GROUPING ARTICLES

TECHNICAL FIELD

The present invention relates a method and an arrangement for controlling a flow of units from at least one incoming track to at least one outgoing track.

BACKGROUND ART

Conveyor systems are known, which handles, diverts, rotates, pushes and/or accumulates products in the manufacturing processes. Such systems can for instance be used in packaging, filling, machining or assembly processes. Particular conveyor systems can comprise diverters designed to distribute products from one to several lanes. Such diverters preferably enable distribution in a continuous motion flow.

In these conveyor systems there is sometimes a need to group products and create gaps between products. A common solution is to use a combination of product clamps and stoppers to enable such grouping. Such a solution is illustrated in figure 1. An unstructured flow 10 of products is entering the machine on an in-feed conveyor 11. The flow is transported to the Stopper 12 at the end of the machine 13.

The Stopper 12 is a device that, when activated, holds back the product flow (e.g. a plate attached to a pneumatic cylinder). Products accumulate against the stopper, and when the accumulated queue of products is long enough a Clamp 14 is activated. The Clamp is positioned a certain distance upstream of the Stopper. When the Clamp is activated the Stopper is retracted and the products 15 between the Clamp and Stopper will be discharged to the downstream conveyor. Groups 15 of products are thereby created. A gap in the product flow is created directly downstream of the Clamp. When the gap is a desired length, the Clamp is released again. When the gap reaches the Stopper, the Stopper is activated again and the cycle starts over. With this solution groups 15 are created with gaps there between, where the products are discharged in groups/slugs with no gap between the products in each slug. As the products are being discharged in slugs, they are supporting each other which can be an advantage for unstable products. The "slug length" (i.e. the number of products in each group/train of products) is determined by the distance between the clamp 14 and the stopper 12 and is therefore more or less fixed during operation.

One problem with this solution is that the possible number of cycles per minute is depending on the speed of the clamp 14 and stopper 12, but also on the friction coefficient of the conveyor belt against the products. This is because when the stopper is retracted, the products to be discharged needs to be accelerated by the conveyor belt. The friction must also not be too large since products are accumulating and may be damaged. Since this effect is limiting the maximum cycle rate, the "slug length" needs to be long in order to reach high throughput. Because of the long slugs and long gaps when running with high throughput, the conveyors upstream, inside and downstream of the machine needs to be long and running at high speeds

Another problem is that the products that are accumulated on the in-feed conveyor are pulsating forward. This can cause product damages and/or dislocations. The reason for the pulsations is the continuous starting and stopping of the product flow, caused by the stopper 12 and the clamp 14.

A further problem is that the products that are accumulated stands still on a continuously running in-feed conveyor. This result in a friction force transferred from the conveyor to the products. In combination with the full stop caused by the stopper and the clamp, the products may be damaged and dislocated.

US 6763929 propose a solution for separating continuously fed products into groups. In this document, the products are fed on a feeding conveyor, where said products are separated and grouped by a first and second conveyor band with locating elements. The elements are anchored into the conveyors at certain distance from each other. Within the distance between an element of the first and an element of the second conveyor a group is formed, which is fed forward at a speed which is lower than the speed of the feeding conveyor. When the group is released, it accelerates on the feeding conveyor away from the next group formed between two other elements. Grouping of products is thereby enabled.

A problem with this solution is that the elements are particularly designed to interact with bottles or similar. It is not possible to have elements mounted on conveyors below the feeding conveyor which intercepts between products independent of the product shape. There is a high risk that the elements hits the products and pushes these away from the feeding conveyor. Another problem is that since the first and second conveyors are run at a lower speed than the feeding conveyor, products are accumulated on the in-feed conveyor and are pulsating forward.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to provide an improved method for creating gaps between groups/trains of products from an unstructured incoming flow of products without interrupting said flow.

The object is solved by means of a method for controlling a flow of units from at least one incoming track to at least one outgoing track. The method comprises the steps of:

- The incoming track feeds the flow of units at a first speed towards a diverter track, which receives said units. Said diverter track comprises a support structure on which said received units rest.

- The diverter track further comprises at least one holding device which holds at least one of said received units and feeds said unit at a second speed being higher than the first speed. - The holding device controls the second speed so that it deviates from the speed of the rest of the units resting on said structure, such that a plurality of said received units are brought together and forms a group of units which is fed to the outgoing track.

The object is also solved by means of an arrangement adapted for controlling a flow of units from at least one incoming track to at least one outgoing track. The incoming track is adapted to feed the flow of units at a first speed towards a diverter track which is adapted to receive said units. Said diverter track comprises a support structure on which said received units rest. The diverter track further comprises at least one holding device which is adapted to hold at least one of said received units and feed this at a second speed being higher than the first speed. The holding device is adapted to control the second speed so that it deviates from the speed of the rest of the units resting on said structure such that a plurality of said received units are brought together and forms a group of units which is fed to the outgoing track.

The main advantage with the present invention is that groups of products can be created in a non-interrupted flow. The incoming flow of products does not need to be restricted in order to create the gaps between the groups. With the present invention, the possible throughput using the new technology is significantly improved. The fact that the products are discharged in slugs, helps making a stable transfer to the conveyor downstream.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in greater detail in the following, with reference to the embodiments that are shown in the attached drawings, in which:

Figure 1 shows a prior art arrangement for creating gaps between groups/trains of products. Figure 2 shows an arrangement for creating gaps between groups/trains of products according to the present invention.

Figure 3 shows a flow chart illustrating the method according to the present invention.

DETAILED DESCRIPTION

The embodiments of the invention with further developments described in the following are to be regarded only as examples and are in no way to limit the scope of the protection provided by the patent claims.

The present invention relates to an arrangement and a method for controlling a flow of products from at least one incoming track to at least one outgoing track. From now on the products will be named units. In spite of the fact that the detailed description describes the method performed by the arrangement, the person skilled in the art realizes that the arrangement, adapted to perform these method steps, is also disclosed in the description.

The incoming track 16 feeds the flow of units 23 at a first speed towards a diverter track 20, which receives said units. See figure 2. The diverter track comprises a support structure 21 on which said received units rest. The support structure may be static. It could for instance consist in a support bed, a tube structure or any other means enabling support and sliding for the received units. The support structure may as an alternative be adapted to move the resting units. It could for instance consist in a conveyor, a linkage or a mechanical arrangement enabling support and active movement of the units. The features and control of the diverter track 20 and the support structure 21 will be described more in detail in the following.

The incoming 16 and the outgoing tracks 19 may consist in one or more tracks. The tracks may comprise a conveyor for feeding the units 23. Other means, such as a linkage, for supporting the units in the respective track are also included within the scope of the invention. The diverter track 20 comprises a holding device. The holding device 18 may consist in at least one conveyor belt with holders 22 adapted to hold the received units 24. The holding device may as an alternative consist in a linkage with holders 22 adapted to hold the received units. The linkage refers to a series of links connected with joints to form a closed chain, or a series of closed chains.

Such holders 22 may for instance be cleats mounted on two conveyors or linkages running on each side of the received units. With such an arrangement, the unit 24 is held by clamping it between one holder/cleat mounted on each conveyor/linkage. The holders/cleats may clamp the unit at top and bottom or from the sides. An alternative is to use one conveyor or linkage with holders wherein these holders have means such as magnets, grippers to hold the units. Any means able to grip and hold the units can be used.

The holding device 18 may as an alternative consist in a mechanical arrangement with at least one holder adapted to hold the received units 24. The arrangement is adapted to enable a reciprocal motion of the holder. Such arrangements may for example involve screw-driven linear units, pneumatic cylinders or robot arms.

In order to enable holding from bottom, the support structure 21 is preferably designed so that the holders 22 can extend through the structure. This is necessary since the structure is arranged so that the received units 24, 25 in the diverter track 20 can support the units from below.

In the following, the control of the flow of units 23 from the at least one incoming track 16 to the at least one outgoing track 19 will be described. At first, the incoming track 27, see figure 3, feeds the flow of units at a first speed towards the diverter track 20 which receives said units. Said diverter track comprises the support structure on which said received units rest.

This step is followed by two further steps, see figures 2 and 3: 1. In the first step, the holding device 18 in the diverter track 20 holds 28 at least one 24 of said received units and feeds said unit at a second speed being higher than the first speed.

2. In a second step, the holding device 18 controls 29 the second speed so that it deviates from the speed of the rest of the units 25 resting on said structure such that a plurality of said received units are brought together and forms a group of units 26 which is fed to the outgoing track 19.

The scope of the present invention is to create slugs of units, without restricting the incoming flow of units 23. This is achieved by using the holding device 18 with the holders 22 that comes in contact only with some of the units in the flow, whereas the other units in each group of units 26 are pushed (or held back) by this unit. The slugs of units are accelerated (compared to the incoming unit speed), which creates a defined gap between each slug of units.

With said control of the diverter track 20, gaps can be created between groups/trains 26 of units from an unstructured incoming flow of units 23 without interrupting said flow. The reason is that the holding device 18 feeds some of the received units 24 at a second speed which deviates from the speed on the incoming track 16.

In the first step the holding device 18 grips at least one 24 of the units. This means that not all of the units that rest on the support structure 21 are gripped. The non-gripped units 25 will only rest on the support structure. The held units 23 will be fed at the second speed. Since this speed is higher than the first speed on the incoming track 16, the held units are accelerated.

The second speed (the speed of the held units 24) is controlled so that it deviates from the speed of the non-held units 25. The second speed may be controlled so that the units held by the holding device 18 pushes the rest of the units resting on the structure forward in the longitudinal direction of flow. This means that groups of units are formed, which comprises one held unit and the non-held units located between two held units downstream from said held unit.

As mentioned, the support structure 21 may be an arrangement such as a conveyor, a linkage or any other means enabling support and active movement of the received units 24, 25. This structure may be run in a third speed which is lower than the second speed. Still, the second speed (the speed of the held units 24) is controlled so that it deviates from the speed of the non-held units 25. The result will be the same as if the support structure were standing still (static). That is, non-held units resting on the support structure will be pushed forward by the held units. Since the non-held units need to be able to slide on the support structure, the friction coefficient needs to be low.

The movable support structure 21 may be run in a third speed which is higher than the second speed. Still, the second speed (the speed of the held units 24) is controlled so that it deviates from the speed of the non-held units 25. The result will be that the units held by the holding device 18 holds back the rest of the non-held units located between two held units upstream from said held unit. The no-held units 25 will accumulate against the held unit 24 in each group of units 26.

The length of the group of units 26 may depend on the speed deviation (between the first and the second speed). The length of the group of units 26 may also be varied by the holding device 18, see fig. 2. In practical terms, the length depends on the pitch between the holders 22 and on the speed difference between the units 23 fed towards the diverter track and the speed of the diverter track 20. The pitch may be varied depending on the mechanical structure of the holding device.

The holding device 18 may be synchronized so that the units 24 are held on a predefined position on the units. This enables formation of exact slug lengths since the holders 22 always grip the units on defined positions. If small variations in the slug/group 26 length are acceptable, the holding device can run freely without being synchronized with the flow of units.

The grouped units 26 are fed by the diverter track 20 to the outgoing track 19. There is normally no gap between the units in the slug/group. In the event that there are small gaps between the products, these are considered as a group of units. As the units are being discharged in groups, they are supporting each other, which can be an advantage for unstable units.

The invention relates to the creation of the gaps, while applications using the gaps (such as a complete diverter) are not discussed. The gaps created between the products can be used in for example a diverter, where the gap can be utilized to shift between two or more conveyor lanes. The diverter comprises a pivoting diverter mechanism for high speed vertical / horizontal distribution of the units 23.

The invention is not to be regarded as being limited to the embodiments described above, a number of additional variants and modifications being possible within the scope of the subsequent patent claims.

For instance, the arrangement may comprise an intermediate track, in the following exemplified by a choke belt 17. The belt is positioned between the incoming track 16 and the diverter track 20. The choke belt is arranged with the purpose of controlling the speed with which the units are fed to the diverter track. The position of the choke belt means that it will feed the flow of units 23 to the diverter track. The choke belt may consist in a conveyor belt, a linkage or any other means such as a mechanical arrangement, which enables support and movement of the units. The choke belt may be omitted if the units 23 enter the diverter track at a controlled speed.

The choke belt may be run in a variable speed, which is lower than the second speed and feed the units 23 towards the diverter track. The choke belt will thereby hold back the units upstream without interrupting the flow of units. This will ensure that the speed of the incoming units does not exceed the second speed at which the held units are fed.

Claims

1. A method for controlling a flow of units (23) from at least one incoming track (16) to at least one outgoing track (19), comprising the steps of:

the incoming track (16) feeding (27) the flow of units (23) at a first speed towards a diverter track (20) which receives said units (23), said diverter track (20) comprising a support structure (21 ) on which said received units rest,

characterized in the steps of

the diverter track (20) further comprising at least one holding device (18) which holds (28) at least one (24) of said received units and feeds said unit

(24) at a second speed being higher than the first speed,

the holding device (18) controls (29) the second speed so that it deviates from the speed of the rest of the units (25) resting on said structure, such that a plurality of said received units are brought together and forms a group of units (26) which is fed to the outgoing track (19).

2. A method according to claim 1 wherein the second speed is controlled so that the units (24) held by the holding device (18) pushes the rest of the units

(25) resting on the structure forward in the longitudinal direction of flow.

3. A method according to claim 2 wherein the support structure (21 ) is run in a third speed which is lower than the second speed.

4. A method according to claim 1 wherein the support structure (21 ) is run in a third speed which is higher than the second speed so that the units (24) held by the holding device (18) holds back the rest of the units (25) in the longitudinal direction of flow.

5. A method according to any of the preceding claims wherein the holding device (18) is synchronized so that the units (24) are held on a predefined position on the units.

6. A method according to any of the preceding claims wherein an intermediate track (17), which is positioned between the incoming track (16) and the diverter track (20), is run in a variable speed which is lower than the second speed and feeds the units (23) towards the diverter track (20).

7. A method according to any of the preceding claims wherein the length of the group of units (26) is varied by the holding device (18).

8. A method according to any of the preceding claims wherein the length of the group of units (26) depends on the speed deviation.

9. An arrangement adapted for controlling a flow of units (23) from at least one incoming track (16) to at least one outgoing track (19), the incoming track (16) being adapted to feed (27) the flow of units at a first speed towards a diverter track (20) which is adapted to receive said units (23), said diverter track (20) comprising a support structure (21 ) on which said received units rest,

characterized in that

the diverter track (20) further comprising at least one holding device (18) which is adapted to hold (28) at least one (24) of said received units and feed this at a second speed being higher than the first speed,

the holding device (18) being adapted to control (29) the second speed so that it deviates from the speed of the rest of the units (25) resting on said structure such that a plurality of said received units are brought together and forms a group of units (26) which is fed to the outgoing track (19).

10. An arrangement according to claim 9 wherein the holding device (18) consists in at least one conveyor belt with holders (22) adapted to hold the received units.

11. An arrangement according to claim 9 wherein the holding device (18) consists in a linkage with holders (22) adapted to hold the received units.

12. An arrangement according to claim 9 wherein the holding device (18) consists in a mechanical arrangement with at least one holder adapted to hold the received units (24), wherein the arrangement is adapted to enable a reciprocal motion of the holder.

13. An arrangement according to any of the claims 9 - 12 wherein the holders (22) consist in cleats clamping the unit (24) at top and bottom or from the sides.

14. An arrangement according to any of the claims 9 - 13 wherein support structure (21 ) is static.

15. An arrangement according to any of the claims 9 - 14 wherein the support structure (21 ) is adapted to move the resting units.

16. An arrangement according to any of the claims 9 - 15 wherein the arrangement comprises an intermediate track (17) which is positioned between the incoming track (16) and the diverter track (20).