GRIPPER HEAD WITH RETAINING MEANS FOR LAYER PADS

Abstract: A lifting head (1) for lifting a plurality of open topped articles comprising a plurality of expandable members (8) adapted to enter the open tops of the articles in the unexpanded condition and expandable to grip the inside of the articles characterised in that the lifting head (1) comprises retaining means (10) for removing a layer pad (21) from or locating a layer pad (21) against the articles.

Description: a " l Gripper head with retaining means for layer pads. This invention relates to a method and apparatus for article handling and particularly to the building of a plurality of hollow articles into a stack in which they can be transported and to the discharging of hollow articles from a stack. It is well known to form a stack of hollow articles in which the articles are arranged in an array of lines and rows and for such arrays of articles to be placed in layers on top of and another with a layer pad therebetween, the layer pads having recesses or formations on the underside adapted to accept the tops of the articles and recesses or formations on the top side to accept the bases of the articles. GB patent no. 2158044 describes such a stack of articles in which the layer pads are themselves designed to nest with one another so that a stack of layer pads can be formed before or after they have been used so that they form a stack of layer pads of minimum height. The formation of a stack of articles with this type of layer pad provides a particularly stable stack of articles which is normally formed on a pallet for ease of movement and transport. In particular such a stack of articles is more stable than a stack in which the articles rest on layer pads having a flat upper surface. Previously described methods for discharging an array of bottles from a stack such as is disclosed in GB 216 8024 A in which an array of articles is pushed off a stack by a transfer arm cannot however be employed. In GB patent application no. 2062577 there is disclosed a lifting head for lifting an array of articles having a downwardly facing apertured surface to contact the articles and means for evacuating a vacuum chamber above the surface. The array is formed at the downstream end of a conveyor and deposited by the lifting head on a cardboard tray placed on top of a previous layer of like articles supported in turn on a pallet. Alternative lifting heads are also disclosed in which inflatable rubber tubes are lowered between e.g. narrow-necked bottles and inflated to grip the rows of containers or expandable members pass into an upwardly open container, the members having a split cone and an actuating member to cause the pair of cone halves to move apart and grip the inside of the containers. For example GB patent specification numbers 2 034 276A, 1 462 677, 1 297 656, 859 752 and 713 770 all describe the lifting of hollow bodies by inserting expandable grippers or lifting heads into the hollow bodies. None of these lifting heads are entirely satisfactory. A lifting head which relies on vacuum requires a suitable flat smooth surface on the articles which cannot always be guaranteed. Furthermore, if the articles are lightweight plastic bottles the vacuum required to ensure that the bottles are lifted can lead to the bottles collapsing inwardly. The use of inflatable tubes between the articles requires further support around the outside of the array and is furthermore dependent upon the upper region of the articles having a suitable shape if they are to be positively gripped by the tubes when inflated. Mechanically expanded members are complicated and expensive to manufacture and maintain. Furthermore, the methods of lifting hollow bodies described in the abovementioned patent specifications are not adapted for use with irregularly shaped containers e.g. asymmetrical containers having small contact areas. This is particularly the case with small containers such as small bottles which have a greater propensity to fall over than larger containers. More particularly, a plurality of small bottles cannot be lifted simultaneously with a corresponding number of lifting heads as the relative positions of the bottles cannot be maintained and the bottles have a tendency to fall over during transport. An object of the invention is to provide an apparatus for and a method of palletising hollow containers in a stable and regular manner. According to one aspect of the present invention there is provided a lifting head for lifting a plurality of open topped articles comprising a plurality of expandable members adapted to enter the open, tops of the articles in the unexpanded condition and expandable to grip the inside of the articles characterised in that the lifting head comprises retaining means for moving a layer pad relative to the articles. Such a lifting head can have the expandable members arranged in a single line and be used for lifting articles from a conveyor and transferring them to build up an array of articles on a layer pad or pallet. Conveniently the number of expandable members in the line corresponds to the number of rows of articles in the array so that all the articles in a single line are transferred simultaneously. Alternatively the lifting head can have expandable members arranged in lines and rows and corresponding in number to either an entire array of articles in a single layer or a part of an array. Thus the articles may be marshalled into a plurality of lines on a conveyor or conveyors and an entire array of articles transferred simultaneously. Alternatively the array may comprise, e.g., half the number of lines and rows in a layer so that four arrays are transferred separately to make up a single layer. Having placed a layer of articles on a pallet or layer pad resting on a pallet a layer card is placed over the tops of the articles and a further layer of articles transferred to build up the stack to the desired number of layers. Preferably the layer pad is of the kind having location means for the tops of the articles so that the spacing between the articles is retained during subsequent transport of the stack of articles. The articles are therefore retained in position so that the articles can be removed or depalletised from the stack by a similar lifting head to that by which the stack has been formed. The layer pad is conveniently provided with holes at each of the article location means, the holes corresponding to the openings in the tops of the articles so that the expandable members can enter the open tops whilst a layer pad is in position resting on the tops of the articles. Thus a lifting head according to the invention can be used to depalletise an entire layer of articles from a stack simultaneously and transfer the articles to a suitable flat surface, e.g. the input to a filling line. After the articles have been released the layer pad still attached to the lifting head can be transferred to a position where it is released to form a stack of layer pads which can be returned to the location where they can be re¬ used to form further stacks of articles. The retaining means can comprise a series of claws movable between a first retaining position where the claws engage the underside of the periphery of the layer pad and a second release position where the claws are disposed outwardly beyond the periphery of the layer pad. The claws are preferably all moved by actuating means simultaneously from one position to the other position. The movement of the claws can be actuated by mechanical, hydraulic or pneumatic means. A filling passage can be provided extending through each of the expandable members. Thus each of the articles being gripped by the lifting head can be filled simultaneously. The invention also provides a method of depalletising open topped articles arranged in a stack comprising layers of articles in an array of rows and lines with a layer pad disposed between each layer and located on the tops of the articles in the array comprising moving a lifting head to insert an expandable member carried on the lifting head through apertures in the layer pad and into the open top of each of the open top articles in the array, expanding the members to grip each of the articles, transferring the array of articles to an article deposit position, and placing the articles thereon, releasing the expandable members and withdrawing the expandable members from the open tops simultaneously with lifting the layer pad from the array. Because the array of articles is deposited with the layer pad still on the tops of the articles the positions of the articles in lines and rows is not disturbed and they can be readily moved from the deposit position in an orderly and predetermined manner without any further marshalling. Preferably the layer pad is then transferred by the lifting head to a layer pad deposit position where it is released. The invention will now be more particularly described with reference to the accompanying diagrammatic drawings in which Figure 1 is an elevational view of one embodiment of a lifting head according to the invention. Figure 2 is a plan elevation of the lifting head of Figure 1. Figure 3 is a sectional elevation of an expandable member; and Figure 4 is a perspective view of one form of layer pad particularly suited for use with the invention. Referring to Figures 1 and 2 a gripper head 1 is shown over a stack 2 of bottles 3 on a pallet 4. The gripper head is carried on a support arm 5 which can be moved to move the lifting head from the position as shown over the stack of bottles to a bottle deposit position and a layer pad deposit position. The lifting head can also be rotated on the support area by pivot mechanism indicated at 6. Therefore, the pivot mechanism 6 facilitates rotation of the gripper head 1 relative to the support arm 5. The lifting head comprises a series of arms 7 each carrying a plurality of expandable members 8 which are described below in further detail. The arms are all carried by a subframe 9 attached to the pivot mechanism 6. The subframe 9 also carries four layer pad retaining claws 10 pivoted at 11 and movable by actuating cylinders 12. As seen in Figure 3 an expandable member 8 comprises a central member 13 attached to an arm 7. The free end of the member 13 has a reduced diameter portion 14 which is surrounded by a flexible sleeve 15 retained on the member 13 by an end cap 16. A passage 17 communicates at one end with the reduced diameter portion 14 and at the other end 18 is connectable to a source of compressed air. As shown in Figure 3 the expandable member is inserted into the open neck 19 of a bottle 3. The member has passed through an aperture 20 in a layer pad 21. Air under pressure can be applied to the passage 17 to cause the flexible sleeve 15 to expand to grip the inside of the bottle neck. For clarity the stack of bottles is shown in Figures 1 and 2 without layer pads between the layers. A layer pad 21 of the type shown in Figure 4 would in practise be provided at the tops of the bottles of each layer. As can be seen in Figure 4 the upper surface of the layer pad 21 is provided with recesses 22 adopted to the shape of the base of the bottles. The underside of the layer pad is also provided with recess formed between two downwardly extending arcuate projections 23 in each of the base recesses of the layer pads. An aperture 24 is provided in each of the bottle top receiving recesses having a diameter through which the unexpanded expandable members can pass but smaller than the outer diameter of the bottle neck. The layer pad has a flat lowermost surface formed by side edges 25. A stack of bottles as shown in Figure 1 having a layer pad 21 between each layer, at the top of the stack and optionally at the bottom of the stack, can be built up using a lifting head as described but without the layer pad releasing claws. The lifting head can have expandable members in one or more lines as required. If a layer pad is required at the bottom of the stack it is first placed in position and the bottles carried by the lifting head and placed thereon until the array is complete. A further layer pad is then placed on the tops of the bottles and a further layer of bottles built thereupon. A completed stack with a layer pad on the top of the bottles in the uppermost layer can then be wrapped for transportation, e.g. from the bottle manufacturer to the filling site. After having removed any outer wrapping the bottles are depalletised at the filling site by a lifting head as illustrated. The stack of bottles is brought to a position where the lifting head can be brought above the stack. The lifting head is then lowered to enter the expandable members through the apertures 24 in the layer pad and into the necks of the bottles. The expandable members are then expanded so that each of the bottles in an array are gripped and the array lifted and moved to a flat surface e.g. at the input to a filling line. When the bottles are in contact with the flat surface the expandable members are contracted. At some point between expansion and contraction of the expandable members the layer pad retaining claws 10 are moved to the first position so that as the lifting head is raised leaving the bottles on the flat surface it lifts the layer pad away from the array of bottles. The lifting head then carries the layer pad to a location where it is released by moving the claws to a second position. The sequence is then repeated until the stack of bottles has been depalletised. Alternatively, a stack of bottles as shown in Figure 1 having a layer pad 21 between each layer, at the top of the stack and optionally at the bottom of the stack, can be built up using a lifting head as previously described with the addition of the layer pad releasing claws 10. For example, the layer pad retaining claws 10 are manoeuvred to grip a first layer pad 21. The layer pad retaining claws 10 position the layer pad 21 while the expandable members 8 are. then manoeuvred to collect and carry the hollow articles. The layer pad retaining claws 10 then release the layer pad 21 onto the hollow articles before positioning them on a pallet. An advantage of this method of creating a palletised layer of hollow articles or bottles is that the bottles are stabilised due to the presence of the layer pad 21 over the bottles which serves to hold the necks of the bottles in position during transport and while depositing the bottles on the pallet. It will be appreciated that the bottles are therefore placed on the flat surface in an orderly and predetermined manner. They can therefore be fed into the filling line without the need for any further orientation or marshalling. If desired the expandable members can be modified to provide filling passages therethrough. For example, the filling passages could be connected to a filling pump. Thus the bottles may be filled whilst the lifting head is in position over an array, or a part of an array, of bottles. The bottles could also be filled with the layer pad in situ to increase stability and prevent bottles from tipping over. The bottles would then be released at the input to a bottle closing line therefore being finally packed into the desired packaging in which they are to be transported to the next distribution site. In alternative embodiments of the invention the expandable members can be replaced by vacuum-operated retaining means, gripping means and the like.

Claims: CLAIMS 1. A lifting head for lifting a plurality of open topped articles comprising a plurality of expandable members adapted to enter the open tops of the articles in the unexpanded condition and expandable to grip the inside of the articles characterised in that the lifting head comprises retaining means for moving a layer pad relative to the articles. 2. A lifting head according to claim 1 characterised in that the expandable members are arranged in a single line. 3. A lifting head according to claim 1 characterised in that the expandable members are arranged in a number of lines and rows corresponding to the lines and rows in a single array. 4. A lifting head according to claim 3 characterised in that the retaining means comprises a series of claws moveable between a first retaining position where the claws can engage the underside of the periphery of the layer pad and a second release position where the claws are disposed outwardly beyond the periphery of the layer pad. 5. A lifting head as claimed in claim 4 comprising actuating means for moving all claws simultaneously between the first retaining position and the release position. 6. A lifting head according to any of the preceding claims having a filling passage extending through the expandable members. 7. A method of depalletising open topped articles arranged on a stack comprising layers of articles in an array of rows and lines with a layer pad disposed between each layer comprising moving a lifting head to insert an expandable member carried on the lifting head through apertures in the layer pad and into the open top of each of the open top articles in the array, expanding the members to grip each of the articles, transferring the array of articles to an article deposit position, and placing the articles thereon, releasing the expandable members and withdrawing the expandable members from the open top. 8. A method according to claim 7 further comprising lifting the layer pad from the array with retaining means mounted on the lifting head. 9. A method according to claim 8 in which the layer pad is transferred to a layer pad deposit position and released from the lifting head.

Inventors: SOMERS MARK GEOFFREY, VAN DER ZON PETRUS WILHELMUS M, SOMERS, MARK, GEOFFREY, VAN DER ZON, PETRUS, WILHELMUS, M.
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1993
Main classification: B65G47
IPC codes: B65B21, B65D45, B65G47, B65G57, B65G59, B65G61