This application is a National Phase filing regarding International Application No. PCT/GB2007/001106, filed on Mar. 27, 2007. International Application No. PCT/GB2007/001106 relies upon British Application No. GB 0609452.8, filed on May 12, 2006, for priority.
This invention relates to devices for maintaining tension in vertical strapping on palletised loads of containers, such as bottles or cans, in which the upright containers are stacked automatically in layers on a pallet (or a dolly) with slip sheets (also known as layer pads) e.g. of polypropylene of the order of 2.0 to 4.0 mm thickness, between the layers, and also one below the bottom layer, each successive slip sheet being placed on top of a layer of containers and each successive layer of containers being pushed laterally en masse or lowered from above on to the preceding slip sheet, the completed stack being topped-off by a slip sheet and a rigid board which is subjected to a downward loading, e.g. of 2 to 3 tonnes, to compact the layers and slip sheets whilst strapping is automatically applied vertically between the pallet and the board, across under the platform of the pallet (or dolly) and across the top of the board. The board is usually formed by four lengths of wood, e.g. each 97 mm wide and 17 mm thick, joined together to form a rectangle having outside dimensions commensurate with the dimensions of the pallet.
Upon arrival at the point of use, the vertical strapping is cut off, the rigid board and top slip sheet removed, and the height of the stack is adjusted so that each layer of containers can be pushed laterally en masse off the slip sheet below on to, e.g., a conveyor feeding a bottling or canning line.
Because the strapping, after securing ends together before removing the downward loading, is of finite length, any subsequent settling of the stack, e.g. due to variation in bottle height, e.g. plus or minus up to 1.0 mm, and/or vibration and/or stretching of the strapping, particularly arising from expansion due to temperature rise subsequent to the strapping operation results in loss of tension in the strapping that can lead to instability of the stack, especially as vibration of the palletised load during transporting can cause ‘bottle-walking’ (or ‘can-walking’) from within the confines of the slip sheets, hereinafter referred to simply as ‘walking’, with disastrous results, especially breaking of bottles, but also denting of cans.
It is, therefore, common practice to apply strapping horizontally around each layer of containers, but there still remains a tendency to ‘walking’ of a layer en masse from palletised loads, especially from loads disposed over wheels of a truck where vibration is particularly intense. It is also known to place on top of each layer a cardboard cap with sides to embrace the outermost containers adjacent their tops, as another attempt to prevent ‘walking’. Any sudden braking and/or impact, such as hitting kerbs or pot-holes, causes rapid destabilisation of the stack following any leading row of containers falling over the adjacent edge of the slip sheet below.
GB-A-2 418 663 describes and claims a device for use in place of the board previously described comprising a pair of rectangular frames each of outer dimensions commensurate with the dimensions of a pallet or dolly on which containers are to be stacked in layers, springs being provided between the frames to urge them apart, and tethering means being provided to limit separation of the frames, whereby, after removal of the downward loading applied whilst vertical strapping takes place, the spring urge between the frames is available to maintain tension in the vertical strapping.
One object of the present invention is to improve the performance of the device described above.
Another object is to provide a simpler construction of device for the purpose aforesaid, with consequent saving in material and manufacturing costs.
According to the present invention, a device for use in place of the board previously described comprises a rectangle having outer dimensions commensurate with the dimensions of a pallet or dolly on which containers are to be stacked in layers, each side of the rectangle comprising upper and lower leaves diverging from hinge means at the inner edge of the side, the lower leaves of all four sides being disposed in a common plane, and spring means urging the outer edges of the upper and lower leaves apart.
The effect of this construction is improved distribution of the loading applied by the lower leaves to the outer rows of containers in a stack.
As regards the device in GB-A-2 418 663 this can be adapted by providing adjacent the inner edges of the frames tethering means limiting separation to such an extent that the effect is to form hinge means between the frames, whereby the springs between the frames urge the outer edges of the frames apart to an extent limited by tethering means adjacent those edges.
However, according to the other aspect of the invention, the spring means is integral with the hinge means; thus avoiding need for tethering means between the leaves.
Such a simplified device may have each of its sides formed from spring steel strip bent longitudinally to form hinge means between upper and lower leaves, with the lower leaves in a common plane and welded together at the corners of the rectangle, and with outer edge portions of the leaves (i.e. remote from the hinge means) along each side of the rectangle bent towards each other into overlapping relationship, to prevent ingress of debris preventing proper use of the device.
Tethering means between the outer edge portions of the leaves may, however, be preferable, being advantageous in enabling pre-loading of the spring means, affording greater effectiveness in maintaining tension in vertical strapping of a load on a pallet. Thus, the extreme edges of the overlapping outer edge portions may be bent so as to hook together.
Alternatively, separate spring means each consisting of upper and lower arms diverging from an arcuate or coiled hinge portion may be encased in plastics material forming upper and lower leaves with co-moulded outer edge portions extending towards each other into overlapping relationship, to prevent ingress of debris preventing proper use of the device, all the lower leaves of plastics material being in a common plane and connected together at the corners of the rectangle, e.g. by welding of mitred ends of the leaves or by snap-fitting means enabling the device to be disassembled for replacement of any damaged sides or for cannibalisation of damaged devices. Thus a plurality of spring means may be assembled by spaced location of their hinge portions along a plastics rod or tube adapted for integration in between the plastics leaves, and the ends of the rods or tubes may be connected together by sockets or spigots on corner pieces.
Tethering means may be provided in the form of snap-engaging projections along the overlapping outer edge portions of the plastics leaves.
A number of embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:—
In
The leaves 22L of all four sides of the lower frame 22 are disposed in a common plane, and the claws 26, 27 are integral with longitudinal ribs 28, 29 respectively on the underside of the upper leaves 21L, the inner claws 27 having greater depth than the claws 26 so that, in the as-assembled condition shown in
This modification of the device of GB-A-2 418 663 has a surprising advantageous effect that, after the device 20 has been placed on top of a slip sheet (or layer pad) 30 on the top of bottles 31 in the top layer of a stack on a pallet or dolly (not shown, but reference is made to FIGS. 1 to 3 of GB-A-2 418 663) and strapping 32 applied whilst the device 20 is subjected to downward loading, as indicated by the vertical arrows in
As indicated in
The device 40 shown in
Alternative means for fixing the sides 41 together is illustrated by
The device 40 does not include any tethering means, so no preloading of the hinge/spring means 42 can be effected. In contrast, a device made up with sides formed of spring steel strip as illustrated by the cross-section shown in
The device 60 illustrated by
Number | Date | Country | Kind |
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0609452.8 | May 2006 | GB | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/GB2007/001106 | 3/27/2007 | WO | 00 | 2/7/2008 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2007/132141 | 11/22/2007 | WO | A |
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20080272348 A1 | Nov 2008 | US |