Cross-Reference to Related Applications

The present application claims priority from Australian Provisional Patent Application No 2004906127 filed on 22 October 2004, the content of which is incorporated herein by reference.

Field of the Invention

This invention relates to a lifting strap and to a method of using a lifting strap.

Background of the Invention

For many years straps and slings have been used to load and discharge cargoes from ocean going vessels and barges. In particular, for a number of years high tensile steel lifting straps have been used to facilitate the loading, stowing and discharge of primary products such as bundles of aluminium ingots, in a process known as the Unit Strap Lift Method, or USLM for short.

In the case of aluminium ingots, for transport from a smelter to an end user, the aluminium ingots are set together in bundles, each of which weighs approximately one tonne. These bundles are held together by straps known as primary straps. In the USLM process, these bundles are stacked one on top of another (i.e. two high) and a high tensile steel lifting strap is applied around the centre of the stacked bundles to provide a means for lifting the stacked bundles on and off barges and ocean going vessels using a crane with an appropriate spreader attachment or the like.

The high tensile steel lifting straps utilised in the USLM operation are often referred to as "M straps" because the top of the strap is generally bent or shaped into an "M-shape" which provides spring in the strap to enable the strap to be applied to the ingot bundles and to retain the strap in place, as well as providing points where the hooks on the spreader attachment can be applied to the lifting strap.

Often, a number of such stacked bundles are consolidated together making up a shipping pack, these can be known as a "Superpacks". The Superpack may be made up of any number of two high bundles consolidated together and which may weight up to 32 tonnes. These Superpacks are delivered to an ocean going vessel or barge positioned under a crane having an appropriate spreader attachment. The spreader attachment has a plurality of hooks which attach to the steel lifting straps of the stacked bundles, and the Superpack is then lifted on board the vessel and stowed appropriately.

For safety reasons, the high tensile steel lifting straps utilised in the USLM operation can only be utilised for four lifts in total. This allows for one lift of the Superpack onto the vessel and one lift to remove the Superpack from the vessel for delivery to the customer where the strap is removed and disposed of. An additional two lifts are provided for in case the Superpack has to be lifted into and out of a barge prior to, or subsequent to, it being stowed in the ocean going vessel.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.

Summary of the Invention In a broad aspect the invention provides a re-useable lifting strap for lifting a bundle of products including a strap comprising a closed rectangle having rounded corners.

In a first aspect there is provided a re-usable lifting strap for lifting a bundle of products including a strap made from a flexible material comprising a closed, generally rectangular loop, having a perimeter of a maximum defined size and including a means for reducing the perimeter of the lifting strap by a relatively small percentage, typically by less than 5%, which means also define two areas of the strap which can act as lifting loops and present for a crane's hooks to attach thereto for lifting the bundle.

Instead of using steel, the lifting strap as described above may be made in woven materials allowing multiple re-use of the strap.

On the inside of two top corners of the strap additional material may be added which is elastic and defines two loops. These loops may be attached to the hooks of a crane for lifting.

Alternatively, in a further aspect of the present invention, the lifting strap may comprise a generally rectangular closed loop incorporating two sections of Velcro, or other fastener means in a top portion adjacent each top corner of the strap. The strap may be applied with the Velcro sections unconnected at one or both corners. The Velcro sections are then fastened together to secure the strap and form two lifting loops which present for a crane's hooks to be attached thereto. More particularly in one aspect of the invention, there is provided a lifting strap for lifting a bundle of stacked products including a strap made from a flexible material

in the form of a closed loop having a lifting end and including a first biasing means extending between first and second zones of the lifting end of the strap, the first biasing means being shorter than the length of the strap between said two zones to define a first loop portion; and a second biasing means extending between third and fourth zones of the lifting zone of the strap, the second biasing means being shorter than the length of the strap between said two zones to define a second loop portion, the arrangement being such that the loop portions are extendable under tension in the strap to enable the strap to be applied to the ingot bundles by stretching the strap, the biasing means assisting in holding the strap in place under tension. Advantageously the loop portions also defining the two lifting points for the stacked bundles.

The strap may comprise a flexible material comprising woven fibres. For example the strap may comprise polyester locked thread webbing, interwoven nylon or other strong woven materials. Typically the straps will be from 40mm to 60mm most typically about 5 Omm wide.

The biasing means are typically elastic or similar material.

In a related aspect, the invention provides a method of attaching a re-usable lifting strap to an upper bundle of product superposed on another bundle of product using a lifting strap made from a flexible material comprising a closed, generally rectangular loop, having a perimeter of a maximum defined size defining an expanded configuration and including a means for reducing the perimeter of the lifting strap by a relatively small percentage, typically by less than 5% to form a reduced configuration, which means also define two areas of the strap which can act as lifting loops and present for a crane's hooks to attach thereto for lifting the bundle the method comprising: placing the lifting end of the strap over the centre of the top of the upper bundle; pulling a lower portion of the closed loop underneath the centre of the lower bundle with the strap in an expanded configuration. forming, or allowing the strap to relax into, the reduced configuration defining lifting loops for a crane's hooks to attach thereto.

In a preferred aspect the present invention also embraces a method of attaching a lifting strap to an upper bundle of product superposed on another bundle of product using a strap made from a flexible material in the form of a closed loop having a lifting end including a first biasing means extending between first and second zones of the lifting end of the strap, the first biasing means being shorter than the length of the strap between said two zones to define a first loop portion; and a second biasing means

extending between third and fourth zones of the lifting end of the strap, the second biasing means being shorter than the length of the strap between said two zones to define a second loop portion, the method comprising: placing the lifting end of the strap over the centre of the top of the upper bundle; expanding the closed loop by pulling the loop downwards applying tension and stretching the biasing means; pulling a lower portion of the closed loop underneath the centre of the lower bundle.

The stacked bundle may be lifting using hooks passing through the loop portions.

The invention also embraces a related method for attaching a lifting strap to an upper bundle of product superposed on another bundle of product using a strap including Velcro portions as described above.

The strap may be used multiple times and may be returned to the product supplier/shipper for re-use .

Brief Description of the Drawings

A specific embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawings in which: Fig. 1 shows a bundle of ingots;

Fig. 2 shows a second bundle of ingots stacked on top of the bundle of ingots shown in Figure 1 prior to application of a lifting strap embodying the present invention;

Fig. 3 shows a first a first embodiment of lifting strap; Figs. 4a and 4b are a close-up views of part of the lifting strap of Fig. 3;

Figs. 5a and 5b are side views of a stacked bundle as shown in Fig. 2 illustrating the securing of the lifting strap in position on the stacked bundles;

Fig. 6 is a front view of the stacked bundles showing the lifting strap in position ready for lifting by a crane; Fig. 7 shows a second embodiment of a lifting strap; and

Figs. 8a and 8b are views of parts of the second embodiment of a lifting strap shown in Figure 7.

Detailed Description of Preferred Embodiments

Referring to the drawings Fig. 1 shows a stack of aluminium ingots which are strapped into a bundle 100 weighing approximately one tonne. As can be seen two primary straps 102 are used to hold the bundle together.

Fig. 2 shows the bundle 100 shown in Fig. 1 with an additional, substantially identical bundle 200 superposed on it prior to the application of a lifting strap (not shown in Figure 2) to secure the stacked bundles together.

Figs. 3 and 4 illustrate a lifting strap 300 embodying the present invention for application to a stacked bundle. The strap is made from 50mm wide polyester locked thread webbing and is in the form of a closed loop. The strap has a first end or bottom portion 302 which in use locates underneath the lowest bundle in the stack, side portions 304, 306 which in use extend along the sides of the stacked bundles and a top or lifting portion 308 which in use, as described below, engages with a spreader crane.

The top portion 308 defines two small lifting loops 310 which are spaced apart at either end of the top portion. As is best seen in Figures 4a and 4b, a length of elastic material 312 extends between two areas or zones of the strap typically about 30 to 80cm apart. The length of elastic material 312 is relatively shorter than the length of strapping between the two areas. This causes the length of strapping between the ends of the elastic to form a loop 310, but at the same time allowing the loop to expand when tension is applied to the strapping stretching the elastic. Figs. 5a and 5b illustrate the application of the strap to the stacked bundles shown in Fig. 2. The top 308 of the strapping is placed above the centre of the top bundle 200 and the first end portion 302 of the strap locates under the edge 500 of the bottom ingot in the lower stack 100. The strap is then pulled downwards and at the same time stretched (which is provided for by stretching of the elastic 312) to allow the first end portion 302 of the strap to swing underneath the bottom ingot in the stack as illustrated in Fig. 5b.

Fig. 6 shows the stacked bundles with the strap in position ready for lifting, although in practice, a number of stacked bundles will be juxtaposed and joined with a belly band into a Superpack, prior to lifting. The use of the elastic material to form the two loops has a number of functions including defining the two lifting points for the bundle, and providing elasticity in the lifting strap to enable the strap to be applied to the ingot bundles by stretching the strap and to hold the strap in place under tension.

Advantageously the woven nylon webbing strap of the present invention is reusable and is therefore more environmentally friendly and cost effective than the

existing disposable high tensile steel lifting straps currently utilised in USLM operations.

Materials other than polyester locked thread webbing may be used for the lifting strap provide that they have the necessary strength and durability. For example interwoven nylon may be used.

Figures 7, 8a and 8b show a second embodiment of a lifting strap 700 which again is a, generally rectangular, closed loop having a bottom portion 702, side portions 704, 706 and a top or lifting portion 708.

As best seen in Figures 8a and 8b, the strap incorporates two sections of Velcro, 800, 802 or other hook and loop type fastener in the top portion 708 adjacent each corner. The strap is applied with the Velcro sections unconnected at both corners, or one corner as shown in Figure 8b. Once the strap is in the correct position for lifting, the Velcro sections 800 and 802 are then fastened together to secure the strap and form two lifting loops 804 which present for a crane's hooks to be attached thereto. It will be appreciated that the strap and method described above may be used for lifting product other than aluminium ingots.

It will also be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.