Background Art A multi-bay palletiser is a palletiser which has two or more palletising bays or stations, each of which receives a pallet to be loaded with articles, such as boxes, by a palletising head. Multi-bay palletisers are frequently arranged with the bays in a line.

In conventional multiple bay palletisers a single conveyor system delivers empty pallets to all of the bays. The system may have a conveyor which runs alongside the bays with a transfer mechanism or mechanisms to transfer the pallets to each individual bay. Alternatively, a conveyor system may run underneath or through the bays. However, in all existing systems loaded pallets are removed from each bay transversely off the palletiser bay line, with the associated need for additional space and transfer mechanisms for each bay to accomplish this.

Typically, further space is required to collate the pallets from the various bays onto a single conveyor, if, for example, they need to be conveyed to a common plastics film wrapping machine.

Disclosure of the Invention In one embodiment of the present invention there is provided a multiple pallet palletising system in which a single transport system both delivers empty pallets to the bays or stations of the palletiser and removes loaded pallets from the bays or stations, so avoiding the need for complex and expensive transfer mechanisms.

In one broad form of the invention the transport system is not positioned to one side of the palletising bays or stations but passes through them, so removing the

need for space on each side of the palletiser for delivery and removal of pallets.

Alternatively if the length of the space available for the system is limited, the pallet dispenser and collection points may be located to one side of the palletising bays or stations with pallets passing through the bays.

In one broad form the invention provides a multiple pallet palletising system including: a plurality of palletiser stations each of which palletises articles on a pallet; transport means for moving loaded pallets from all the palletiser stations; said transport means transporting loaded pallets from at least one of the palletiser stations through the plan view of another of the stations.

The system may include means to move pallets located in a station through which the transport means transports a loaded pallet either horizontally or vertically to ensure the pallets do not block the loaded pallet.

In most forms of the invention vertical movement is preferred. However, when loading of a pallet occurs at a single level with a vertically moving gripper head, horizontal motion may be preferred.

In another broad form the invention provides a palletising system for loading goods onto pallets including: a plurality of palletiser stations, each of which palletises articles onto a pallet; pallet transport means for transporting loaded pallets away from the palletiser stations; said pallet transport means transporting loaded pallets from at least one of the palletiser stations through or beneath another of the palletiser stations; lift means for lifting a pallet above the pallet transport means;

said lift means adapted to raise a first pallet in a first palletiser station to a level to permit the pallet transport means to transport a loaded pallet through the first palletiser station below the first pallet.

The system may palletise articles onto pallets at a fixed working level or may palletise articles onto pallets which are at various working levels. The fixed working level may be at or just above the level at which loaded pallets are removed. The lifting means may raise a pallet to above the working level or levels to permit a loaded pallet to pass beneath.

Alternatively, the working level or levels may be sufficiently high above the conveying surface that a loaded pallet may pass beneath without the need to modify the height of the pallet being loaded.

The pallet transport means may merely remove loaded pallets or it may also deliver empty pallets to each palletiser station. Where a rotating arm or articulated arm type palletiser is used, the gripper head may move empty pallets from a supply point to the palletiser station and the transport means remove loaded pallets.

The transport means may include a conveyor belt system; a roller conveyor type system; one or more shuttle cars; a carousel system or any other suitable mechanism for moving loaded pallets.

When the transport means moves both empty and loaded pallets it may receive empty pallets at one end of the palletiser bays and discharge loaded pallets at the other end. Alternatively, empty and loaded pallets may be received and discharged at the same end. In addition, either or both of the pallet dispenser and collection points may be arranged at the sides of the bays if lengthwise space is limited.

Brief Description of the Drawings The invention shall be better understood from the following non-limiting description of embodiments of the invention and the drawings, in which

Figure 1 is a plan view of a first embodiment of the invention; Figure 2 is a side view of the first embodiment; Figure 3 is a side view of a second embodiment of the invention; Figure 4 is a side view of a third embodiment of the invention.

Figure 5 is a plan view of a fourth embodiment of the invention.

Best Mode of Carrying out the Invention Referring to Figures 1 and 2 there is shown a multi-bay palletiser 10. The palletiser 10 has three palletising bays 12,14,16 arranged end on end in a line.

The bays are arranged in a straight line but if desired may be arranged on a non- linear line.

The palletiser 10 is of the type having a palletising head 18 which moves longitudinally and transversely but generally not vertically and in which each palletising bay has lift means to adjust the vertical position of the respective pallet in the bay as the pallet is loaded. In the embodiment shown a single palletising head 18 services ail three palletising bays but each bay has its own article delivery conveyor 20,22,24 respectively, for delivering articles to be palletised.

This is not essential to the invention and a single conveyor may be utilised for delivery of articles for palletising on all the bays or each bay may have its own palletising head. Alternatively, multiple conveyors may be provided to provide different articles, each of which may be palletised onto multiple pallets. In addition, the gripper head may have substantial vertical movement.

A pallet dispenser 26 is located at one end of the palletiser and dispenses pallets 28 onto a conveyor system 30 which runs longitudinally through the palletiser.

The conveyor system includes a conveyor belt 32 which runs between drive rollers 34,36, which are located at each longitudinal end of the palletiser. The conveyor system 30 extends from one end of the palletiser to the other and a pallet may be passed through the palletiser from one end to the other.

Each palletising bay is provided with lift arms 38,40 which move vertically. The work surface of the conveyor belt 32 is modified by rollers 42 so as to define recesses into which the lift arms 38,40 may be lowered, so as to allow a pallet to pass over the lift arms 38,40, such as when an empty pallet is delivered to the bay.

The lift arms 38,40 move the pallet vertically so that the palletising head 18 may deposit articles onto the pallet or a previously completed layer of articles. As each layer is built up the lift arms lower the pallet to a new working level so as to enable another layer of articles to be deposited on the already built up layer. The basic operation of the delivery aspect of the conveyor system is disclosed in Australian patent specification No. 57959/94, the contents of which is incorporated herein. The operation of the palletising head 18 and lift arms 38,40 in loading pallets is described in Australian patent specification No. 46071/93 and US Patent No. 5525029, the disclosures of which are incorporated herein.

Once a pallet has been loaded, the lift arms 38,40 lower the loaded pallet 44 (see Figure 2) to return it to the conveyor belt 32. With the lift arms 38,40 positioned fully below the general plane of the belt 32 the loaded pallet 44 is then conveyed toward exit point 46 at the opposite end of the palletising system from the pallet dispenser 26. To do this the pallet 44 and the articles 50 loaded on the pallet must pass through any"downstream"palletising bays. In the Figure 1 and 2 embodiment the pallet in the middle bay 14 is loaded and so must pass through bay 16 to reach the exit point 46. To do so the pallet 52 located in bay 16 is raised so that itself and its associated lift arms are above the top of the stack of articles 50 located on the loaded pallet 44. The system may include sensors to detect the top of a loaded pallet, which will vary depending on the articles being palletised, so that the lift arms of downstream bays are only raised upwards by the minimum amount necessary. As can be seen in Figure 2 the pallet 52 in bay 16 is partially loaded and so when it is raised sufficiently to allow a loaded pallet to pass underneath, the top of the articles on pallet 52 lies above the loading height of the palletising head 18. Thus, whilst a loaded pallet is being transferred to exit point 46, pallet 52 cannot be loaded with articles. However, the palletising head 18 may continue to load articles onto all upstream bays, such as bay 12.

Further it is possible to arrange the loading height so that an empty pallet or the top surface of a partially loaded pallet may remain at the required working level and continue to be loaded whilst a loaded pallet passes underneath. This will be discussed further with reference to Figure 4. It will be appreciated that the downstream pallets may be moved horizontally rather than vertically to provide clearance for a loaded pallet.

Once a loaded pallet has passed through a bay, the lift arms of that bay may be lowered to return the pallet to the correct working level and palletising of that pallet may continue. Thus loading of a pallet is only disrupted whilst a loaded pallet is passing through the bay. The system may include sensors to detect the position of a loaded pallet on the conveyor so that downstream pallets are only raised as the loaded pallet arrives and are returned to the working level as soon as the loaded pallet has passed.

The loaded pallet 44 passes to exit point 46. Exit point 46 may be provided with an automatic plastics wrapping machine to wrap the articles on the pallet prior to removal from the conveyor 30 by conventional means, such as a fork lift for transfer to a delivery vehicle or the like.

Figure 3 shows a second embodiment of the invention in which separate conveyor belts are provided in each bay of the palletising system and at the entry and exit points to the bays. It will also be appreciated that a roller type conveyor system may be utilised for movement of the pallets, with appropriate gaps in the rollers to allow the lift arms 38,40 to pass below the common conveying surface.

Referring to Figure 4 there is shown a variation of the Figure 1 and 2 embodiment. In this third embodiment the basic structure is the same as in the Figure 1 and 2 embodiment and the same numbers are used to indicate the same components. The only change is that each of the bays 12,14,16 is significantly taller than the bays in the Figure 1 and 2 embodiment.

In the Figure 4 embodiment the partially loaded pallet 52 in bay 16 is at its maximum working height and has just received a first layer of articles. The pallet 54 in bay 12 is almost fully loaded and is in the process of receiving its last

article. Thus the pallet 54 and its associated lift arms 38,40 are at the lowest working level. The pallet 44 in bay 14 is fully loaded and is about to be moved along conveyor 30 to exit point 46. As can be seen, the top of articles 50 on pallet 44 is below the pallet 54 and lift arms 38,40 of bay 12 and would also be below a fully loaded pallet in bay 16 if pallet 52 were full loaded. Thus, pallet 44 may be moved through bay 16 to exit point 46 without the need to move the pallet 52 in bay 16 out of the way. Thus palletising of any"downstream" palletising bays is not disrupted when moving a loaded pallet to the exit point 46.

Referring to Figure 5 there is shown a variation of the invention in which the pallet dispensing apparatus 26 and the exit point 46 are located to one side of the line of palletising stations. The conveyor or conveyors supplying articles to the system are preferably on the opposite side of the system from the dispenser 26 and exit point 46. It will be appreciated that the dispenser 26 may be located to one side and the exit point 46 to the other side of the line of palletising stations, so as to have a Z-shaped configuration. It will also be appreciated that one of the pallet dispenser 26 and exit point 46 may be in line with the palletising bays and the other located to one side.

This system has use where the length of the system needs to be minimised. The transport system operates as in the previously described embodiments so as to allow loaded pallets to pass beneath pallets in the other bays.

It will be appreciated that where conveyor belts or rollers are utilised that a transfer mechanism may be required at each end to change the direction of motion of the pallet from lengthways to sideways. However, where a shuttle car or cars or the like is utilised this may be achieved by allowing the or each shuttle car to have motion in both the lengthways and sideways directions.

Whilst the invention has been described with reference to palletising systems which do not utilise a vertically moving palletising head or heads it will be appreciated that such palletising heads may be utilised. Alternatively a conventional articulated robot may be used. Further, whilst the embodiments receive empty pallets from one end and discharge loaded pallets at the other

end, this is not essential and a single end may be utilised for both the entry of empty pallets and the exiting of loaded pallets.

It will be appreciated that other arrangements, modifications and variations may be made to the embodiments described herein by those skilled in the art without departing from the spirit or scope of the invention.

Industrial Applicability The invention has industrial applicability in the palletising of articles.