PROCESS AND WORKSTATION FOR SEMI-AUTOMATIC MULTI-LAYER STACKING ON A LOAD CARRIER

The invention relates to a process for semi-automatic multi-layer stacking of a load carrier, in particular a pallet, with objects to be packed having different dimensions, in a spatial arrangement and a corresponding workstation.

The automatic stacking of a support or load carrier without supporting sides, in particular a pallet or a rolling truck, with objects to be packed in order to form a stack, i.e. palletisation, is known per se. However, in this case objects to be packed which have uniform size or dimensions are by laid down by robots, gripping devices etc. at computationally-determined locations.

In contrast, the process of automatically loading a load carrier with objects to be packed which have different dimensions in order to form a stack is a matter of so- called automatic "mixed-case" palletising.

In that case, different aspects must be taken into account and these enormously increase the complexity compared with "simple" stacking. A subsequent object to be packed can therefore only be stacked or placed on a previous object in a satisfactory manner if this previous object has a flat or even surface which should also be oriented approximately horizontally, and if the object can bear the weight of the further objects placed on it without being damaged.

Furthermore, the stack formed should have a certain stability so that, amongst other things, it does not fall over during transportation. Wrapping with sheeting does help but cannot by itself stabilise an incorrectly formed stack.

In addition it is becoming increasingly desirable that consideration be made of the desired order of unloading. For delivery to stores like-items are preferred to be stacked together in order to optimise the unloading process.

The stacking of different objects to be packed or items with different sizes or dimensions is thus usually carried-out manually since the requirements of stability of the stack, packing density within the stack as well as the order of loading and unloading thereby dictated and, not least, the stackability of the items are extremely

high and have not thus far been fulfilled or only partially fulfilled by the known automatic processes and devices.

However traditional manual 'dispatch lane' packing processes require the operator to build a load carrier on the floor from the bottom up. This means the operator is only working at an ergonomic packing height for a short period of time, approximately half way through the build. They are also not fast enough for modern dispatching.

In contrast, the object of the present invention is to provide a process and a workstation for semi-automatic multi-layer stacking of a load carrier with objects to be packed which have different dimensions in a spatial arrangement, which process and workstation permit mixed-case stacking in a flexible manner and with a high throughput, whilst also maintaining accuracy and efficiency and with consideration for the operators' wellbeing.

This object is achieved by the process depicted in claim 1 and by the workstation stated in claim 17. Advantageous embodiments are given by the subordinate claims and the description.

Semi-automatic is to be understood as the manual stack building (stacking) with automated and/or semi-automated support for the operator.

The concept of the present invention has come about due to the requirement to pack load carriers, such as pallets, at higher rates whilst also maintaining accuracy and efficiency and with consideration for the operators' wellbeing. This means that a semi-automatic process of packing load carriers has been developed in order to push the throughput rates beyond that of a manual distribution centre and to assist with the building of stable load carriers.

According to the invention the process for semi-automatic multi-layer stacking of a load carrier, in particular a pallet, with objects to be packed having different dimensions, in a spatial arrangement, comprises the following steps: computer-aided determination of the order of the objects to be packed on the support;

delivering the separate objects to be packed in an order required for this purpose by means of a conveying system; taking the objects to be loaded from the conveying system by at least one operator who lays the respective object down at a desired spatial position on the stack being formed on the load carrier; presenting the load carrier in a hopper like device which defines a work surface and forms a support for the stack being formed on the load carrier on four sides as it is packed; orientating the movable load carrier at a height of approximately one stacking layer below the work surface within the hopper like device.

Further the load carrier is alternatively supported by either a load carrier support or a load carrier feed device. This allows for minimising down times due to change of the load carriers and allows for a constant work flow.

Preferably the load carrier is initially supported by the load carrier feed device within the hopper and after leaving the hopper like device by the load carrier support.

The operator may indicate when a load carrier is finished stacking and an empty load carrier may be inserted into the hopper like device by means of the load carrier feed device. For this the workstation may include a pushbutton, foot pedal etc.

This allows for automatic removal when the stack building is finished the load carrier, i.e. the operator does not have to worry about the changing of the load carriers.

An empty load carrier may be inserted into the hopper like device as soon as the prior stacked load carrier has been lowered sufficiently.

Additionally the stacked load carrier may be stabilised during stacking after leaving the hopper like device and the stacking takes place directly on the final load carrier. The stacked load carrier is preferably stabilised during stacking after leaving the hopper like device and the stabilisation takes place underneath the hopper like device.

This allows for finishing the stabilisation while a new empty load carrier is inserted by the load carrier feed device, as the stacked load carrier is supported and moved by

the load carrier support. Therefore the stack is stabilised at all times, even after leaving the relatively short chute of the hopper like device.

The stacked load carrier may be stabilised by wrapping with sheeting, netting or the like.

Because the stacking takes place directly on the final load carrier, i.e. without a temporary or intermediate support, the finished stack on the load carrier needs not be shifted, which saves time and increases throughput as well as simplifies the process and related workstation.

In order to achieve a constant working height it is envisaged that the load carrier can be lowered incrementally by approximately one packing level height once each level is complete. The objects or cases can be fed via a conveying system and delivered at the same height as the work surface in order to eliminate any further need for the operator to reach or bend unnecessarily. These units can be of varying size, weight and shape, load carrier stability is also an issue and some means of ensuring this during packing and during transport is of high importance. Therefore the hopper like device supports the stack with its four sides. To increase the packing rate and also load stability, the system also provides objects in an appropriate order to aid the process. This helps increase the operator efficiency and throughput rates.

To increase the packing rate and also the load stability, the system also provides objects in an appropriate order to aid the process. This helps increase the operator efficiency and throughput rates.

In order to reduce the manual handling required and increase the throughput rate, the load carrier is automatically injected into its starting position and also transported away after finishing packing. Likewise an empty load carrier is inserted into the hopper like device as soon as the prior stacked load carrier has been lowered sufficiently.

As the operator decides where the next objects are to be placed it is preferable that the work surface defines a buffer area in which he temporarily place objects. The operator will be constantly monitoring the delivery conveyors so as to determine

where best to place the objects. If he finds it better to place them out of the delivery order he may then use the buffer area, formed by the flange, preferably in the region of the interface to the conveyors.

The conveying system will arrive at the hopper like device level with the work surface, so that the operator only has to slide the objects over the work surface without lifting.

To speed up the process or handle different objects independently two independent conveying systems may deliver the objects. These may arrive in parallel at the hopper like device.

The load carrier feed device may also act as a load carrier destacker for load carriers presented in a stacked configuration. The feed device will therefore take the top most load carrier off a stack of load carriers from the load carrier delivery conveyor. This allows to maximise the capacity of the delivery conveyor and also save space.

It is envisaged that the complete process in the preferred embodiment may be undertaken as follows:

The operator workstation will be in the form of a table with a chute like opening which will be known as a 'hopper'. The hopper will form a support for the stack on four sides as it is packed. It will also form a low-friction workbench by means of a flange forming a work surface. This workbench will be at an ergo- nomic height which the operator can use to slide cases into position around the load carrier. This will eliminate the need for the operator to lift the cases, therefore reducing the workload, fatigue and chances of injury.

The load carrier will be presented into the hopper by means of a load carrier feed device at a height of approximately one packing layer below the work surface. This will enable the packing to begin on the first layers without delay. This device will also act as a load carrier destacker after stacking is finished. The objects to be stacked will be presented to the operator by means of a conveyor system, the height of which will match the height of the hopper. The objects will also be presented in an appropriate position to give the operator easy access. This is to reduce the need to reach or stretch. The hopper will also be equipped with additional buffer areas so the operator has the option of placing objects aside to pack these when convenient. Optionally the interface

region between the work surface and the conveyor system may allow for diverting the incoming objects to either side.

Packing will commence when the load carrier is in place and the first layers can be packed in the load carrier's starting position directly onto the final load carrier without use of temporary or intermediate supports. In this phase the load carrier is supported by the feed device.

Once the packing layer is no longer at an ergonomic height the operator can index the stack downwards by a pre-defined height so that the following layers can be packed. The operator will index the stack by using a pushbutton or foot pedal integrated into the hopper structure which drives the load carrier feed device. This process will continue until the load is fully built. When the load carrier feed device has reached its lower limit within the hopper, a second load handling device (the load carrier support) will take the weight of the load seamlessly, i.e. without delay, while stacking commences. This will allow the load carrier feed device to be retracted and allow it to collect the next empty load carrier from a stack. The carrier stack will be provided by a transport system, the delivery conveyor.

In order to maintain the stability of the load carrier during loading, it is initially supported by the hopper side walls. However, the hopper is short and can only support the stack during its initial build. Once beyond the scope of the hopper and during "transit" an additional method is required. For this reason, a stretch- wrapper will be integrated into the structure and the wrapping of the product will commence as soon as the stack is at an appropriate height. This can occur on the lower part of the load while the packing operation is completed on the upper part therefore reducing any down-time.

Integrating the stretch wrapper into the structure will ensure that the wrapping occurs as close to the hopper as possible. This ensures that the amount of unsupported stack is negligible. When the packing operation is completed, the operator will press a 'packing complete' pushbutton, integrated into the hopper, and the stack will index away while the wrapping process continues until complete. The finished stack will be removed on a transport system. As soon as the packing operation is complete and the stack has lowered sufficiently in the hopper a new load carrier is inserted into position by the load carrier feed device so the packing process can begin again. This will eliminate

any delay between each packing process, as the insertion of the new load carrier takes place even though the wrapping has not finished yet. The objects will be supplied by the conveyor in appropriate order to aid stable load carrier building and also in the correct order that 'family grouping' is achieved. This will ensure like for like products are together on the carrier upon arrival in the store. Objects will also be grouped according to height, weight and crush class.

A device for carrying out the above process is defined in claim 16. Preferred embodiments are defined in claims 17 to 30.

Such a workstation for semi-automatic multi-layer stacking of a load carrier - in particular a load carrier - in a spatial arrangement with objects to be packed having different dimensions, has at least one conveying system for supplying the objects to be packed separately in the required order, and also has a handling work place for at least one operator who takes the object to be loaded from the conveying system and lays it down at a desired spatial position on the stack being formed directly on the final load carrier. It further encompasses a hopper like device, in which the load carrier is presented and which defines the work place including a work surface and also forms a support for the stack being formed directly on the final load carrier on four sides as it is packed, and that the load carrier is supported by means of a movable load carrier support.

The workstation further includes a load carrier feed device for inserting empty load carriers into the hopper like device and in that the hopper like device and the load carrier feed device are adapted to allow the load carrier to be initially supported by the load carrier feed device within the hopper at a height of approximately one stacking layer below the work surface within the hopper like device and after leaving the hopper like device by the load carrier support.

The load carrier support includes an elevator for lowering and/or raising the (final) load carrier. Preferably the load carrier support includes a vertical lift elevator with a support means for the load carrier.

The load carrier feed device includes a load carrier delivery conveyor, a vertical lift

elevator with retractable forks and the retractable forks may be adapted to be inserted horizontally into the pallet. The vertical lift elevator with retractable forks will be adapted to pick off the top load of a stack of load carriers presented on the load carrier delivery conveyor.

The support means for the load carrier will be adapted to support the load carrier from below.

This allows for seamless exchange of load carriers without delay.

Empty load carriers may be fed into the hopper like device from below by means of a load carrier feed device. This load carrier feed device will also initially perform the function of the load carrier support.

The load carrier is transferred between the load carrier feed device and the load carrier support as soon as the load carrier leaves the hopper chute while stacking commences.

The transfer takes place when the load carrier feed device has reached it's lower limit in the hopper. When this occurs, the load carrier is met by the load carrier support and supported on it's underside. This allows the forks of the load carrier feed device (inserter), which are within the profile of the load carrier, to be retracted.

The side wall of hopper like device facing the load carrier feed device has apertures for allowing the retractable forks and the load carrier supported on them to enter the hopper like device. The apertures should have a slit like form to allow the retractable forks to be lowered within the hopper like device.

The workstation further includes a wrapping unit arranged below the hopper like device for layer wise stabilising of the stack being formed upon the final load carrier during stacking after leaving the hopper like device.

In a preferred embodiment the hopper like device forms a chute with a flange forming the work surface, which preferably surrounds the top side opening of the hopper like device circumferentially and functions as a sliding plate.

Additionally the workstation may include a buffer area that is defined by the work surface. The buffer area, formed by the flange, preferably in the region of the interface to the conveyors, allows for temporarily "pushing" objects out of the way to change the order of stacking.

The workstation may include two independent conveying systems for delivery of the objects to be packed, and preferably the conveying system(s) at the hopper like device will be level with the work surface.

Summarising the inventions allows for

• Improvements in efficiency and ergonomics.

• Objects to be fed at very high rates.

• Down-time greatly reduced. • Significant reduction of manual lifting.

• Integrated stretch-wrapper.

• Unique load handling device for load carrier (pallet) insertion and de- stacking.

• Hopper to support load while packing. • 1 or 2 man operation with optimum product positioning.

• Carrier insertion above packed stack while wrapping process finishes.

• Streamlining of product, i.e. ensuring product arrives in correct order, (crush class, etc.)

• Buffering area for objects. • Wrapping as built improves stability.

• Integrated elevator with control from hopper.

• Control system integrated into workstation.

• Product positioned so it can be accessed easily.

• Low friction surface on hopper for sliding product.

Further advantages, properties and features of the invention are given by the following description of an exemplified embodiment with the aid of the drawing in which

Fig. 1 shows a schematic perspective view from above of a workstation for semi- automatic multi-layer stacking of pallets and

Fig. 2 shows a schematic perspective view "through" the transparent workstation of Fig. 1 .

The figures show a workstation 1 for semi-automatic multi-layer stacking of a pallet P in a spatial arrangement with objects to be packed W having different dimensions.

The workstation 1 includes a hopper like device H, in which a pallet P is presented and which defines a work place 3 including a work surface 4 and also forms a support 5 for the stack S being formed directly on the final pallet P on four sides as it is packed.

The hopper like device H forms a chute 6 with a flange 7 forming the work surface 4, which surrounds the top side of the chute opening 8 of the hopper like device H circumferentially and functions as a sliding plate 9. The four internal side walls of the chute 6 function as the support 5 on four sides of the stack S.

This "workbench" is at an ergonomic height which the operator O can use to slide objects W into position around the pallet P in the hopper like device H. This eliminates the need for the operator O to lift the objects W, therefore reducing the workload, fatigue and chances of injury.

The workstation 1 has a conveying system 2 for supplying the objects to be packed W separately in the required order. The conveyor system 2 includes two conveying systems 2A, B, which are segmented belt conveyors that end in a roller conveyor and arrive at the hopper like device H in parallel and level with the work surface 4. In the region of the interface between the conveyor system 2 and the hopper like device H the work surface 4 is widened. This widened area defines a buffer area 10 for the objects W and also allows for an ergonomic position of an operator O as it has an appropriate cut-out 1 1. A second operator may be positioned opposite side.

The work place 3 is configured for at least one operator O who takes the object W to be loaded from the at least one conveying system 2, slides it over the work surface 4 and eventually lays it down at a desired spatial position on the stack S being formed directly on the final pallet P. Alternatively he may place the object out of the way within

the buffer area 10, so as to place the object W at a later point of time, e.g. after a later arriving object W which he would like to place first.

Further the workstation includes a movable load carrier support 12 for orientating the pallet P at a height within the hopper like device H of approximately one packing layer below the work surface 4.

The load carrier support 12 includes a vertical lift elevator 13 for lowering and/or raising the pallet P, which comprises support arms 14, spaced apart, so that the pallet P may rest on them, when transferred from the initial load carrier feed system 15.

The support arms 14 include transport means to allow for moving the finished stack / pallet from the workstation onto a further conveyor.

The workstation further comprises a load carrier feed system 15, for inserting an empty pallet P into the hopper like device H from below.

The load carrier feed system 15 includes a load carrier delivery conveyor 16, which delivers a stack of empty pallets, and a vertical lift elevator 17 with retractable forks 18, which initially are inserted into the pallet P and can be retracted, so that the pallet P can be transferred to the support arms 14 of the load carrier support 12. The retractable forks 18 are carried by a wagon 19 on the vertical lift elevator 17, which allows for horizontal movement of the pallet P on the forks 18, so that these may be positioned in the hopper like device H even though the load carrier feed system 15 is offset.

The load carrier support 12 further includes a load carrier outfeed transport system 23 for transporting the wrapped and finished stack together with the pallet to its final destination, e.g. outbound delivery station.

As can be taken from the figures, the hopper like device H is arranged above the load carrier support 12 and above the load carrier feed system 15, which are positioned in a plane below the work place 3 together with a wrapping unit 20.

The wrapping unit 20 is therefore also arranged below the hopper like device H

directly below the lower opening of the chute 6 for layer wise stabilising of the stack S being formed upon the pallet during stacking after leaving the chute 6 of the hopper like device H. The wrapping unit 20 comprises a film feed unit 21 which is movable on along a centred circular path 22 around the stack S/pallet P coming out of the chute 6.

The complete process of semi-automatic pallet stacking with the embodiment described above may be performed as follows:

The pallet P is inserted into the hopper H by means of a load carrier feed system 15 at a height of approximately one packing layer below the work surface 4. This will enable the packing to begin on the first layers without delay.

The side wall 24 of hopper like device H facing the load carrier feed device 15 has apertures 25 for allowing the retractable forks 18 and the pallet P supported on them to enter the hopper like device.

The side apertures 25 have a slit like form to allow the retractable forks 18 to be lowered within the hopper like device H and still enable support of the stack.

In a plan view the apertures 25 have the form of the symbol pi (π).

The device 15 will also act as a pallet destacker by moving into a position adjacent to the pallet stack and inserting the forks into the uppermost pallet. This can then be lifted clear of the stack and transported to the feed position.

Packing commences when the pallet P is in place within the hopper like device H and the first layers can be packed in the pallet's starting position directly onto the pallet P without use of temporary or intermediate supports.

The objects W to be stacked are presented to the operator O by the conveyor system 2. The order of the objects to be packed W on the pallet P has been determined by a computer based on the packaging list. The separate objects to be packed W are then delivered in the order required for this purpose. The objects order is appropriate to aid stable pallet building and is also in the correct order that 'family grouping' is achieved. This will ensure like for like products are together on the pallet upon arrival in the

store. Objects will also be grouped according to height, weight and crush class.

The operator O shifts the objects W to be loaded from the conveying system 2 without lifting them by sliding them over the work surface 4 and lays the respective object W down at a desired spatial position on the stack S being formed on the pallet P.

The hopper H is also equipped with additional buffer areas 10 so the operator O has the option of placing objects W aside to pack these when convenient. Optionally the interface region between the work surface 4 and the conveyor system 2 may allow for diverting the incoming objects to either side. So that two operators may work in an alternating fashion.

Once the packing layer is no longer at an ergonomic height, due to the stack building, the operator O will index the stack S downwards by a pre-defined height so that the following layers can be packed.

The operator O indexes the stack S by using a pushbutton integrated into the hopper structure which drives the load carrier feed device 15 (or the load carrier support 12, see below).

This process will continue until the stack S is fully built.

When the load carrier feed device 15 has reached its lower limit within the hopper H, approximately 800 mm below the top of the work surface 4, the load carrier support 12 will take the weight of the load.

The pallet P is transferred between the load carrier feed device 15 and the load carrier support 12 automatically as soon as the pallet P leaves the hopper chute 6 while stacking commences. The operator takes no notice of this process.

The transfer takes place when the load carrier feed device 15 has reached it's lower limit in the hopper H. When this occurs, the load carrier P is met by the load carrier support 12 and supported on it's underside. This allows the forks 18 of the load carrier feed device, which are within the profile of the load carrier P, to be retracted.

From now on the pallet P together with the stack S is supported from below by the load carrier support 12.

This allows the load carrier feed device 15 to be retracted and to collect the next empty pallet from a stack for the next job. The pallet stack is provided by a delivery conveyor 16.

In order to maintain the stability of the pallet P during stacking/loading, it is initially supported by the hopper side walls 6.

However, the hopper H is short and can only support the stack during its initial build.

Once beyond the scope of the hopper H and during transit an additional stabilisation method is required. For this reason, a stretch-wrapper 20 is integrated into the workstation 1 and the wrapping of the product commences as soon as the stack S is at an appropriate height, i.e. below the lower opening of the hopper chute 6. This takes place layer wise on the lower part of the stack S while the packing commences on the upper part therefore reducing any down-time. The operator takes no notice of this automatic process.

Integrating the stretch wrapper 20 into the structure will ensure that the wrapping occurs as close to the hopper as possible. This ensures that the amount of unsupported stack is negligible.

When the packing operation is completed, the operator O will press a 'packing complete' pushbutton or foot pedal, integrated into the hopper like device H, and the stack S will automatically index away while the wrapping process continues until complete.

The finished stack is then removed on the transport system 23.

As soon as the packing operation is complete and the stack S has lowered sufficiently in the hopper (see above) a new pallet P is inserted into position automatically by the load carrier feed device 15 so the packing process can begin again. This will eliminate any delay between each packing process, as this may take place even though the

proceeding pallet and stack are still being wrapped.

Reference list

1 workstation

2 conveyor system

3 work place

4 work surface

5 chute

6 side walls

7 flange

8 chute opening

9 sliding plate

10 buffer area

1 1 cut-out

12 load carrier support

13 vertical lift elevator

14 support arms

15 load carrier feed system

16 load carrier delivery conveyor

17 vertical lift elevator

18 retractable forks

19 wagon

20 wrapping unit

21 film feed unit

22 circular path

23 load carrier outfeed transport system

24 side wall of hopper like device H facing the load carrier feed device 15

25 apertures

P pallet

W object to be stacked

O operator

S stack

H hopper like device