The present invention relates to an arrangement for palleting machines of the type stated in the preamble of the subsequent main claim.
When transferring a layer or tier of bags or cartons from a conveyor to the discharge plate in palleting machines of the above type it is usual that the object or objects located at the rear when viewed in the direction in which the layer is transported will not be completely transferred by the conveyor to the discharge plate since the objects already transferred exert a resistance to further dis- placement which is larger than the displacing force exerted by the conveyor on the said last objects. Hence it is necessary either to make use of an additional pusher .bar so as to move the entire layer on to the discharge plate or to utilise the next layer on the conveyor for pushing the first layer entirely on to the discharge plate. In the latter case it is then necessary for the second layer to be held back with the aid. of a locking bar while the discharge plate is pulled back in order to transfer the first layer on to the underlying pallet or layer. Once the discharge plate has been returned to its initial position the next layer can be moved on to the discharge plate after raising the locking bar.
In order to avoid the above inconvenience it is desirable to enable the transfer of all objects in a layer to the discharge plate without using a pusher bar or without the aid of the next layer on the conveyor as described above. This can be achieved in accordance with the invention by providing at a certain distance above the conveyor a further conveyor parallel with the latter, v/hich can be raised and lowered so as to rest against the objects in the layer carried forward by the said first conveyor. Since both conveyors are driven at the same speed all objects in the layer are moved forward between the said conveyors and are thus trans¬ ferred completely on to the discharge plate, since every single object is held fast and moved forward with a force adequate to push the first objects further along the discharge plate.
If the objects in the layer, which is frequently referred to as a "tier", consist of filled bags of somewhat different thickness
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or bulk it is necessary to pass them through a pressing station where the bags are pressed to uniform thickness so that the layers of bags placed one above the other on the pallet rest stably upon one another in a proper stack. This pressing operation can be carried out advantageously in conjunction with the transfer of the layer to the discharge plate, by means of the said second conveyor located above the first conveyor in accordance with the present invention. In other words, the said first and second conveyors constitute a pressing station which can be provided as an independent unit at the end of a conveyor on which layers are formed.
A specimen embodiment of the invention is described below with reference to the drawing which shows a specimen embodiment in purely diagrammatic form and where fig. 1 shows the outgoing section of the palleting machine with discharge plate and pallet store as well as pallet removal conveyor seen from the side, fig. 2 shows the discharge plate and the pallet removal conveyor seen from the end, and fig. 3 shows the output end of the discharge plate seen from above.
Fig. 1 shows the discharge end of a palleting machine, that is to say a belt conveyor 1 with a locking bar 2 capable of being swung up and down and which in the raised position permits individual objects such as cartons or bags or the said objects arranged in layers or so called tiers to pass, and which in the lowered position holdsback individual objects or layers on the belt conveyor ' . Above the end of the belt conveyor 1 there is a further conveyor, e.g. a belt conveyor 3, with support rollers 3 '• The belt conveyor 3 is made to be adjustab in height above the belt conveyor 1 so that it can be set to abut against layer 9 of individual objects 10 arranged in a certain pattern in the front section of the palleting machine. At the end of conveyor belts 1 and 3 there is a discharge plate 4 capable of being moved to and fro and with a surface having a low coefficient of friction. Below the discharge plate 4 there is an elevating mechanism, only the fork arms 7 of which, which can be raised and lowered, are shown in fig. 1. The fork arms 7 °a^ °e lowered between the rollers of the pallet removal conveyor 8 below so that an empty pallet 6 from the pallet stor
can be brought up on the conveyor 8 and raised from the latter to the load position under the discharge plates 4, 5 β_τ.ά then lowered in steps while loading is in progress and down on to the pallet removal conveyor for removal from the palleting machine. Fig. 2 shows the discharge plate 4 in an arrangement where it is capable of sliding within guide 4' within a frame 11.
Fig. 3 shows the conveyor 1 with the upper conveyor 3 seen from above. At the end of the said conveyors is the discharge plate 4 with a layer or tier $. During operation of the palleting machine a layer or tier is formed on the conveyor belt 1 and carried forward by the latter past the locking bar 2 and below the upper conveyor 3 which is set in such a way as to abut or press down upon the top of the layer levelling its surface if the layer consists of full bags, whereupon the layer is pushed out on to the discharge plate 4- Since all objects 10 in the layer 9 are'clamped fast between the drive conveyors 1 and 3 J also the last obj'ects in the layer are pushed away entirely from the conveyors 1 and 3 ^ on to the discharge plate 4- The discharge plate is then withdrawn while the layer is held fast by the locking bar 12 so that the layer is deposited on pallet 6 below or on a previously deposited layer on pallet 6. The pallet 6 is lowered in steps by the elevating mechanism over a height corresponding to the thickness of the layer 9 until the pallet is fully loaded whereupon it is lowered on to the pallet removal conveyor 8 for removal in the direction of arrow A. At the same time an empty pallet is brought up by the conveyor 8 and raised by the elevating mechanism with the aid of fork arms 7 until it reaches the upper loading position beneath the discharge plate 4 , whereupon the above operations are repeated.
All operations can be controlled automatically in as such known manner with the aid of pneumatic and/or hydraulic driving devices and an automatic system controlling the latter.
On the discharge plate 4 there may be guide bars 12 which bring the objects 10 in layer closely together while they are being moved on to the discharge plate. During the actual transfer of the layer 9 on to the underlying layer or pallet 6 the objects are simultaneously brought closely together since they rest against the transverse bar 12 which pushes the layer from the discharge plate 4
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while the latter is being pulled back.
If provided, the pressing function exerted by the conveyor 3 in respect of the objects 10 in layer 9 can, as stated initially, be utilised not only for the purpose of transportation proper but also to level the surfaces of the objects 10 when the latter consist of full bags. Hence the conveyor 3 may also be referred to as the "pressing conveyor", .and this conveyor together with e.g. a separate conveyor belt may be arranged at the output end of a palleting machine for further transportation and pressing of the layers prior to their being moved to the discharge plate 4- In this way it can be made unnecessary to provide the pressing station itself in the palleting machine, it being possible to arrange the former at the output end of the palleting machine since it combines the operations of pressing of e.g. full bags in the layer and complete transfer of the layer on to the discharge plate 4-
When changing the pallet layer 9 ~ -~n be held back in the pressing station (bag levelling station) with the aid of a locking bar (not shov ) which is moved to the locking position at the same time as the pressing conveyor 3 is raised from the top surface of the layer 9- As a result the force moving the layer 9 forward is considerably reduced so that the latter is easily retained by the locking bar.
This method of storage and retention can be applied when there is little friction between the objects 10 in the layer and the lower conveyor 1.
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