GB2351722A

GB2351722A - Forming layers and stacks of containers

Info

Publication number: GB2351722A
Application number: GB9920018A
Authority: GB
Inventors: Frank Oakes
Original assignee: ROTAPAK Ltd
Current assignee: ROTAPAK Ltd
Priority date: 1999-07-02
Filing date: 1999-08-25
Publication date: 2001-01-10
Also published as: GB9920018D0; GB9915468D0

Abstract

Containers moved in a single-file formation by a conveyor 3 are transferred into an out-of-line formation by means 5, 17, thus forming a layer of containers at a stacking station 23 for addition to the bottom of a stack of such layers to be placed on a pallet 33. The operations can also be performed in reverse order. Transfer of the containers into the layer formation may be effected by an oscillatory arm pushing some of the containers in direction 15 following a curved guide 17. This may be controlled by a container sensor and gates, Figure 4. Stack formation employs lifting members (27, Figure 3) retractably engaging edge parts of the containers.

Description

2351722 Container Handling

Field of the invention

The invention relates to container handling and in particular to handling containers in the form of plastic baskets or trays which are used to transport various types of products from manufacturers, producers and suppliers to retailers of these products. Typically such baskets or trays are used many times, being returned by the retailers to the source once the products have been unloaded. Such reusable plastic baskets or trays are referred to as "Returnable Transport Packaging" (RTP) in the industry.

These containers may be used to transport, for example, packets of frozen food, loose or packaged vegetables and many other products.

Background of the invention

The plastic containers (baskets or trays) of the type with which this invention is concerned are provided with a pair of arms in the form of metal rods located at both ends of the square or oblong, open-topped container. Each arm, known as a bale arm, extends along an upper edge of the side of the container, each end of the bale arm being located in the respective recess or slot located in the body of the container. The arrangement is such that the bale arm can be moved between at least two positions. In the first position, the bale arm lies outside the open top of the container. With the two bale arms in this first position, then two or more containers may be stacked in a "nested" configuration with one container lying almost wholly within another lower container. The bale arms are used in this position when the containers are empty and are to be returned to their source. In this way, a stack of containers will take up a minimum amount of space.

When the bale arms are in a position other than that for nested stacking, they extend across the container at a position spaced inwardly from their respective end walls. Accordingly, when containers are stacked one upon another they are each seated on the bale arms of the next lower container and are therefore in a "denested" 1 configuration. The bale arms are then said to be "inboard" whereas when they are their "nesting" position they are stated to be "outboard".

Some containers allow only a single inboard position for the bale arms. Others are designed such that there are two or more inboard positions which differ from each other by the height of the bale ann relative to the container. In a first inboard position, the bale arm may be located at the height of the upper edge of the container.

In a second inboard position the bale arm may be located well below the upper edge of the container. The first inboard position would be used when the container is substantially full of the product to be transported. The second inboard position may be used when the container is substantially less than full.

The containers of the type with which this invention is concerned are typically transferred over short distances in single stacks on wheel supports known as dollies.

Over longer distances, or where substantial quantities of goods are being moved, the containers are moved on larger pallets which may loaded on vehicles and/or transported by means of fork lift trucks. The containers are arranged on the pallet in a plurality of stacked layers. Typically there may be five stacks arranged in a three by two formation, that is to say, each layer comprises three pallets arranged side-by-side with long sides adjacent and two further pallets arranged end to end with long sides adjacent the short sides of the first three containers.

Loading or unloading a pallet has hitherto been carried out manually. Considerable time is required to undertake such an operation. With loaded containers, considerable strength and dexterity are also required, particularly when dealing with the containers at the top of each stack.

If the containers are to be transferred between a conveyor, on which the containers are arranged in a single in-line formation, and a pallet, then the operation requires not only the loading or unloading of the pallet but the rearranging of the containers between one formation (that on the conveyor or that on the pallet) and the other 2 formation. It would be advantageous for there to be machinery which could carry out the procedure currently undertaken manually. However such machinery, in replicating the procedure carried out by human operator, would be very complicated and take up a considerable amount of space as it would require the handling of containers at different heights as the stacks are built or unbuilt and the raising and lowering of containers at the side of the stacks. Furthermore, the need to transfer containers between one formation and another adds to the complexity of the operation.

Statements of invention

According to the present invention there is provided apparatus for transferring containers between a conveyor, on which the containers are arranged in a single inline formation, and a pallet, on which the containers are ranged in a plurality of stacked layers, each layer having an out-of-line formation, the apparatus comprising a station for accommodating said plurality of stacked layers, each layer being in substantially said out-of-line formation, means located at such station for adding or removing a layer of containers to or from the bottom of said plurality of stacked layers, means for feeding each layer to or from said station in substantially said formation and means for converting the formation of said layer between an in-line formation and said out-of-line formation.

Reference will be made hereinafter to the loading of full or partially full containers from a conveyor on to a pallet but it should be understood that apparatus of the invention may be used to transfer empty containers from a conveyor to a pallet or indeed may carry out an unloading operation (pallet to conveyor) whether of full, partially full or empty containers. Indeed a single apparatus may be adjustable so that it carries out any of these operations as desired.

The present invention also provides a method for transferring containers between a 30 conveyor, on which the containers are arranged in a single in-line formation, and a pallet, on which the containers are arranged in the plurality of stacked layers, each 3 layer having an out-of-line formation, the method comprising adding or removing a layer of containers to or from the bottom of said plurality of stacked layers at a station for accommodating said plurality of stacked layers, feeding said layer to or from said station in substantially said formation, and converting the formation of said 5 layer between an in- line formation and said out-of-line formation.

Brief description of the drawings

The accompanying drawings are as follows:

Figure I illustrates the formation of containers on a pallet; Figure 2 is a diagrammatic view showing apparatus of the present invention; Figure 3 illustrates detail of that part of the apparatus Figure 2 concerned with changing the formation of the containers; Figure 4 illustrates the formation of layers of containers; and Figure 5 illustrates alternative apparatus of the invention.

Detailed description of the invention

Embodiments of the invention will now be described, by way of examples only, with reference to the accompanying drawings.

Referring to Figure I of the accompanying drawings, there is illustrated a typical formation of a layer of containers I as they are located on the pallet. In this example, each container has a length of 600mm and a width of 400mm and they are arranged in a three by two formation or format with two pallets in line longitudinally and three ftirther pallets in line transversely, the five containers being arranged into a rectangle of dimensions 1200 x I 000mm.

When full of goods, such as packets of frozen food or packaged or loose vegetables, the containers may be arranged in the above described formation on a pallet with the stacks being at least ten layers high. As a result the pallet carries a considerable weight and height of containers.

4 In order to load a pallet with stacks of containers in the above described formation, apparatus of the invention, such as that described with reference to figures 2 to 4, may be used. Referring particularly to Figure 2, containers 1 are fed one by one, with a long side leading, by means of conveyor 3 to a formation converting station 5. The feed conveyors associated with station 5 extend into adjacent station 21. The first three pallets to be fed to station 5 proceed through this station in a straight line until they are brought to a standstill at positions 7, 9 and 11 in station 2 1. The next container is fed to station 5 to the position indicated by 13 and is then pushed in the direction indicated by arrow 15, that is to say, at right angles to the initial direction of movement. Container 13 engages a curved guide 17 as a result of which a further movement, effected by a feed conveyor extending parallel to conveyor 3, carries the container to the position indicated at 19 in station 21.

A fifth container then assumes the position indicated at 13 and is also directed out of its original line and into alignment with container 19. The three in-line containers are separated from the two in-line containers by a central partition 25. As a result the formation of the five containers at station 21 is substantially that of the three by two formation required for loading on to the pallet.

Referring to Figure 3, station 21 is provided with a housing 23 in the form of a tower for accommodating a plurality of stacked layers in the three by two formation. The housing 23 is provided with a container lifting mechanism including lifting platforms 27 arranged along the walls 29 and 31 of housing 23 and also on each side of the partition 25. These lifting platforms 27 are arranged at the same level as each other and are capable of being lifted and lowered together and also extended and retracted in a direction towards and away from the containers 1.

At the bottom of the housing 23 there are located two side-by-side feed conveyors which extend from station 5 into the housing. These feed conveyors transport the containers from station 5 into the housing. In addition a further pair of feed conveyors extend from housing 23 in the opposition direction, that is to say, away from station 5. These feed conveyors may be raised or lowered above or below the level of the first-mentioned feed conveyors and are used to transport a pallet 33 into and out of the housing 23.

Once a first layer of containers 1 is situated within housing 23 in the three by two formation, the lifting mechanism within the housing is operated. The lifting platforms 27 are located below the upper lip or rims 35 of the containers and with these lifting platforms extended towards the containers, they are raised thereby raising the containers above the feed conveyors on which they previously rested. The layer of containers is raised until the bottom of the containers is at a height above the feed conveyors greater than the height of a container. At this point another layer of containers is fed through station 5 into the housing below the first-mentioned layer. The upper layer is then lowered by means of the lifting mechanism until the base of the containers of the upper layer rests on the inboard bale arms of the lower layer of the containers. The lifting platforms are then retracted and moved downwardly below the level of the rims 35 of the new lower layer. The lifting platforms are extended outwardly and then raised, carrying with them both layers of containers to a level sufficient to allow a further layer of containers to be located therebeneath.

This process is repeated until a plurality of complete stacks has been formed within housing 23. At this point all the layers are raised above the feed conveyors. That feed conveyor on which pallet 33 rests is now raised to a level just above the feed conveyors used to transport the containers. The pallet feed conveyor is then operated to feed the pallet into the housing 23 below the stacks of containers. The lift mechanism is then operated to lower the stacks of containers on to the pallet, following which the lifting platforms are retracted. The pallet feed conveyor is then operated in the reverse direction in order to drive the pallet out of housing 23.

Due to the presence of partition 25 within housing 23, the set of three in-line 30 containers is at this stage separated from the other set of two containers. In the desired formation on pallet 33, the stacks of containers are located in substantially 6 abutting relationship. In order to achieve this guides 37, mounted down each side of the pallet feed conveyor are inclined inwardly in a direction away from housing 23. As a result the two sets of containers are moved close together as the pallet proceeds between the inclined guides 37. The pallet comes to a standstill beyond guides 37 and it may then be accessed by, for instance, a fork lift truck for further transportation.

Figure 4 shows further detail of part of the above described apparatus. Drive motor 39 powers the conveyors at infeed speeds of up to 120 ft/min, the containers passing through various sensors and gates according to a pre-programmed schedule.

Motor 39 turns drive shaft 41 for the infeed conveyors and provides a pivoting shaft and tail end shaft for the multiple conveyors leading into the housing 23. A sweep arm 43 is provided in order to sweep particular containers along the path 15 (Figure 2) at station 5.

In operation containers full of product, with their bale arms in the stacking position, are fed by conveyor 3 and are counted by sensor 45 and allowed through gates 47, 49 and 51 to stop 53 to the positions indicated by 7, 9 and I I in Figure 2.

Once three containers have been counted, gate 51 is activated to stop the next two containers which are stopped at gates 49 and 5 1. Sweep arm 43 moves the first of these containers past sensors 55 and through to stop 53. The second of these containers is then handled in the same way. As a result a layer of containers in substantially a three by two formation is formed in station 21. The further stages of the operation are then carried out as described above.

Station 73 is the empty pallet loading station and the fully loaded pallet unloading station.

7 Referring to Figure 5 of the accompanying drawing, there is illustrated apparatus similar to that described above and having an infeed section at 61 where single containers with bale arms in the stacking position are fed on conveyors into the system through a series of sensors and gates. At station 63, the containers are rearranged into the required formation for stacking, in this case, in a three by two formation.

At station 65 there is located an automatic layer stacking unit 67 including housing 69. In addition the apparatus includes an automatic palletising station 71 where a 10 fully formed load of containers is situated for pallet introduction and loading.

P15762.1 8

Claims

1. Apparatus for transferring containers between a conveyor, on which the containers are arranged in a single in-line formation, and a pallet, on which the containers are arranged in a plurality of stacked layers, each layer having an out-of- line formation, the apparatus comprising a station for accommodating said plurality of stacked layers, each layer being in substantially said out- of-line formation, means located at such station for adding or removing a layer of containers to or from the bottom of said plurality of stacked layers, means for feeding each layer to or from said station in substantially said formation and means for converting the formation of said layer between an in-line formation and said out-of-line formation.

2. Apparatus according to claim 1 wherein the means for adding or removing a layer of containers to or from the bottom of said plurality of stacked layers comprises lifting platforms which are capable of being lifted and lowered together and also extended and retracted in a direction towards and away from the containers.

3. Apparatus according to claim 1 or claim 2 wherein the means for feeding each layer to or from the station comprises a feed conveyor.

4. Apparatus according to any of the preceding claims wherein the means for converting the formation of the layer between an in-line and out-ofline formation comprises a formation converting station.

5. Apparatus according to claim 4 wherein the formation converting station includes guide means.

6. Apparatus according to any of the preceding claims further comprising a drive motor which powers the means for feeding each layer to and from the station which accomodates a plurality of stacked layers.

9

7. Apparatus according to claim 6 further comprising a sensor and a gate which convert the formation of the layer between an in-line and out-of-line formation.

8. Apparatus substantially as hereinbefore described with reference to the accompanying diagrams.

9. A method for transferring containers between a conveyor, on which the containers are arranged in a single in-line formation, and a pallet, on which the containers are arranged in the plurality of stacked layers, each layer having an out-of-line formation, the method comprising adding or removing a layer of containers to or from the bottom of said plurality of stacked layers at a station for accommodating said plurality of stacked layers, feeding said layer to or from said station in substantially said formation, and converting the formation of said layer between an in-line formation and said out-of-line formation.

10. A method substantially as hereinbefore described with reference to the accompanying diagrams.