GB2366758A

GB2366758A - Extensions of material from a bag body, such as bulk material bag, are folded and joined, eg. stiched, to form handles

Info

Publication number: GB2366758A
Application number: GB0019365A
Authority: GB
Inventors: Ronald Maurice Hourston; Geoffrey Edward Page
Original assignee: DORTON PACKAGING Ltd
Current assignee: DORTON PACKAGING Ltd
Priority date: 2000-08-07
Filing date: 2000-08-07
Publication date: 2002-03-20
Also published as: GB0019365D0

Abstract

A bag, such as a bulk material bag, comprises a handle formed by the folding of at least two extensions A,B of material, extending from the bag body, so that one at least partially overlays the other, and joining the extensions A,B together by stitching them, to form a bag handle. Various configurations of numbers of folds, overlaying and stitching configurations are possible. Also disclosed is an associated method of forming the bag handle.

Description

<Desc/Clms Page number 1> IMPROVEMENTS IN OR RELATING TO LIFT BAGS FOR BULK MATERIAL This invention relates to improvements in or relating to lift bags for bulk material, such bag having a loop or loops at its upper end by means of which the bag and bulk material contents can be lifted and transported by a forklift or hook, and which loop(s) comprises direct extensions of the side walls of the bag.

The invention has been developed primarily in connection with a lift bag of the type used by manufacturers of bulk material which is sold and stored in large volumes. Such bags can be used by the manufacturers of e.g. fertilisers, and can hold, for example, up to two tonnes in weight.

A lift bag typically is made of woven synthetic material such as polypropylene, and usually (although not essentially) has an inner liner of plastics film (polyethylene or other suitable impervious material) in which the bulk material is stored. The filling of the inner liner usually takes place by first inflating the liner with air to facilitate the pouring-in of the material, followed by charging of the inflated liner with the bulk material. The liner is then usually sealed-up by any suitable means, and is either attached to the outer lift bag by a tie, or is hooked into the outer lift bag in any convenient way.

The outer lift bag usually has an upper carrying loop or loops by means of which the bag and its contents can be lifted by a forklift or a hook, and then transported to a storage site. It is usual for the outer lift bag to be a fabric woven from suitably strong and weather resistant synthetic material such as polypropylene. By reason of the warps and wefts from which the fabric is made, the bag can have sufficient

tensile strength in both warp and weft directions, which makes the bag suitably strong to withstand loads which are applied to the wall of the bag during lifting, and during storage.

one way of making the outer lift bag involves starting with a length of woven tube, which is folded inwardly on itself at its two longitudinal edges to form gussets. The gusseted tube is secured by folding and stitching along its bottom end, or by other means, to form the bottom of the bag, and the opposite end is slit down the middle, followed by stitching together the resultant separate two top ends of the tube to form the lifting loop of the bag. Where the bag end is slit to form four top ends of the tube, two lifting loops are formed by stitching the tube top ends together in pairs.

The upper end of the tube is gathered into a form in which the above-formed slits open out to form opposed V-shaped openings in the front and back of the top end of the tube, which are bridged-over by the top loop(s). A binding strip of material, e.g. a strip of coated polypropylene, is wrapped around the or each top loop to confine the warp tapes of the woven material and to render it capable of being engaged by a forklift arm or hook.

It has been found that the step of stitching together the two or four separate resultant top ends of the tube in the manner in which it is done conventionally, followed by applying the binding strip(s) of material, increases the complexity and expense involved in manufacturing the conventional lift bag.

It is an aim of the present invention to provide a new arrangement of a lifting loop of a lift bag, which will enable the lift bag to be manufactured in a more simple and less expensive manner.

According to the present invention, there is

provided a lif t bag, f or bulk material, f ormed f rom material having two separate extensions at the upper end of the lift bag, which two separate extensions have been connected together to provide a lifting loop of the lift bag, each separate extension comprising a plurality of layers of the material of which the lift bag is formed, and the lifting loop having been formed by laying one unstitched end portion of one separate extension flat on an unstitched end portion of the other separate extension, then by folding the two unstitched extension end portions together at least once thereby to produce at least one fold, and then by stitching the folded extension end portions together to secure the lifting loop.

In a lift bag formed from material having four separate extensions at the upper end of the lift bag, two lifting loops can each be formed by the above- described method.

Preferably, the two unstitched extension end portions of a lifting loop are folded together in a direction along the length of the lif ting loop, thereby to produce at least one fold extending along that same direction.

Each of the two extensions of a lifting loop may comprise for example two or four layers of material, so that laying the end portion of one separate extension flat on the end portion of another separate extension provides a stack of four or eight layers of the material of which the lift bag is formed. Alternatively, each of the extensions may comprise a different number of layers, perhaps even just one, depending on the construction of the material used for making the bag.

If the two extension end portions of a lifting loop are folded together just once before stitching, so that the lifting loop is doubled in thickness, the,

lifting loop will comprise eight or sixteen layers of material. It is, however, possible to fold the extension end portions together more times, to provide a lifting loop which is three or even four times thicker than when the one extension end portion is laid on the other extension end portion, thereby to provide a lifting loop comprising twenty-four or thirty-two layers respectively of the material of which the lift bag is formed. Even more folds could be employed if appropriate.

The more layers of material which are stitched together, the stronger the lifting loop will be.

After stitching, the lifting loop may be gathered- in or folded further to make it narrower in a direction transversely of the direction along the length of the lifting loop.

A lifting loop formed in accordance with a preferred embodiment of the invention, has been found to be sufficiently strong so as not to require a binding sleeve extending around the lifting loop.

Although the invention has been described hereinbefore with regard to a lift bag, it will be understood that the invention also extends to a corresponding method or methods of forming a lift bag.

For a better understanding of the present invention and its relation to the prior art, and to show how the invention may be put into effect, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 shows a conventional loaded lift bag standing at rest; Figure 2 shows a cut length of tube from which a lift bag can be made; Figure 3 shows the tube of Figure 2 in cross section; Figure 4 shows a step in conventionally providing

a lifting loop starting from the length of tube shown in Figure 2; Figure 5 shows the lifting loop of Figure 4 after being stitched conventionally; Figure 6 shows an alternative way of stitching the lifting loop of Figure 4 conventionally; Figure 7 shows the lifting loop of Figure 5 or 6 after being gathered together and with a binding sleeve applied conventionally; Figure 8 shows a proposed way of forming a lifting loop after the stitching indicated in Figure 5; Figure 9 shows an initial step in forming a lifting loop in accordance with a preferred embodiment of the present invention; Figure 10 shows how the initial lifting loop shown in Figure 9 can be folded in embodiments of the present invention; and Figure 11 shows various alternative methods of stitching employed in embodiments of the present invention after they have been folded.

Figure 1 shows a conventional loaded lift bag manufactured from circular woven polypropylene fabricl and having a capacity of up to two tonnes. The bag is shown at rest on a horizontal surface, and the bag may be used with or without a polyethylene liner.

The bag has a bottom seam or seams (not visible in Figure 1) to form a stable base, with a sewn and gathered top loop 1 covered with a binding sleeve 2 to form a single point of lift.

Figure 2 shows a length of cut tube from which the bag of Figure 1 is made, shown in a laid flat condition. The tube has open top and bottom ends, and no longitudinal seams, in particular at its longitudinal edges.

The longitudinal edges of the cut tube are folded sharply inwardly to provide two gussets 3 and 4, which

are folded to have sharp inner edges running the whole length of the tube shown in Figure 2. The gussets 3 and 4 are also shown in the tube cross-section of Figure 3.

Figure 2 further shows that the top end of the tube is slit down the middle thereof, to provide two separate extensions at the upper end of the tube, each separate extension comprising four layers of the material of which the tube is formed.

These separate extensions will eventually form the lifting loop of the finalised lift bag, and the end portions of the two separate extensions are designated A and B in Figure 2.

If it is desired to provide the finalised lift bag with two lifting loops, each separate extension A and B can be split into two separate half -extensions, by making slits down the opposed inwardly-directed edges of the two gussets 3 and 4. The resultant four separate extensions can be brought together in two pairs to provide two lifting loops.

Figure 4 shows the next step in the method of manufacturing the conventional lift bag, wherein the end portion B of one separate extension of Figure 2, is laid f lat on the end portion A of the other separate extension thereof- The two separate extension end portions A and B are now overlapped. The skilled man will appreciate that this operation will be performed twice it two lifting loops are to be provided. For the sake of simplicity however, in the description and drawings it will be assumed that only one lif ting loop is to be provided.

Figure 5 shows how conventionally one or more lines of stitching are made transversely of the direction of the extent of the lifting loop, to join the separate extension end portions A and B together.

The inset in the top right-hand corner of Figure 5

shows that the total number of layers of material making up the lifting loop at this stage is eight, that is four layers in the extension end portion A, on top of which are four layers making up the separate extension end portion B.

Figure 6 shows an alternative method of forming the loop to that of Figure 5, wherein the two separate extension end portions A and B are brought together side-by-side before having the line or lines of stitching join them together. In Figure 6 the two extension end portions A and B can be imagined as being brought together in a manner similar to that of two hands in an attitude of prayer.

Figure 7 shows how the stitched loop of Figure 5 or 6 is then gathered or bunched together transversely of its direction of extent, and a binding woven polypropylene sleeve 2 then applied around the gathered lift loop 1, and stitched along the length of axial extent of the sleeve 2, along the direction of extent of the lifting loop 1. The primary purpose of the sleeve 2 around the lift loop is to confine or bind all the vertical warp tapes of the woven material within 'as small and central a bunch as is reasonably possible, thereby equalising the length of and load borne by each warp tape.

The inset in the top right-hand corner of Figure 7 shows diagrammatically a section of the lifting loop 1 in the direction of the arrows shown in Figure 7, showing the gathered or folded extension ends A and B, with the binding sleeve 2 extending around the gathered or folded extension ends.

Figure 8 shows an alternative way of forming the lifting loop 1, by taking the overlapped and stitched lifting loop of Figure 5 or 6 and by folding the stitched loop over twice so that there are three layers of the two extension end portions A and B lying one on

top of another. Then, an additional arc of stitching 5 is applied to keep the layers of the lifting loop 1 together.

The resultant arc-stitched loop is shown in perspective in the main part of Figure 8, in plan view looking down at the top of the lifting loop as shown in the top left-hand corner inset of Figure 8, and in cross-section indicated by the arrows in the top right- hand corner inset of Figure 8. This cross-section clearly indicates that the two extension end portions A and B are folded together twice, so that there are three double layers of end portions A and B lying one on top of another.

Turning now to a preferred embodiment of the present invention, starting from the same tube of material as is shown in Figures 2 and 3, the two extension end portions A and B are firstly laid one on top of another as shown in Figure 9, correspondingly to the step shown in Figure 4 prior to the application of stitching as shown in Figure 5 and 6.

The difference in the Figure 9 lifting loop is that, before any stitching is applied, the two extension end portions A and B are folded together at least once thereby to produce at least one fold. Previously, it has been thought essential to apply, as a first step, stitching as shown in Figures 5 and 6 in order to provide sufficient strength.

Four separate examples of how the two extension end portions A and B may be folded together are shown in Figure 10, wherein for the sake of simplicity each extension end portion A and B is assumed to consist of just one layer of the material of which the lift bag is formed.

It is to be remembered however, that the tube shown in Figures 2 and 3 has upper extensions with end portions A and B each of which extensions comprises

four layers of the material of which the lift bag is formed. Laying one extension end portion B on the other extension end portion A accordingly provides a stack of eight layers of material.

If the two extension end portions A and B are folded together just once before stitching, so that the lifting loop is doubled in thickness, the lifting loop will comprise sixteen layers of material.

If as shown in the top and bottom examples of Figure 10 however, the extension end portions A and B are folded together twice to provide a lifting loop which is three times thicker than when the one extension end portion B is simply laid on the other extension end portion A, a lifting loop comprising twenty-four layers of material will be formed.

If on the other hand the two extension end portions A and B are folded together three times before stitching, so that the lifting loop is trebled in thickness, the lifting loop will be four times thicker than when the one extension end portion B is simply laid on the other extension end portion A, thus providing a lifting loop comprising thirty-two layers of material. This situation is shown in the two central examples shown in Figure 10.

The more layers of material which are stitched together, the stronger the lifting loop will be. The lifting loop is shown in Figure 10 to be folded in a direction along the length or direction of extent of the lifting loop, so that the folds extend along that same direction.

Figure 11 shows four examples of patterns of stitching which may be applied to any one of the four folding examples shown in Figure 10, or indeed to any other folding example according to the present invention. Unlike the conventional and proposed examples already referred-to, the stitching shown in

Figure 11 is the first stitching to be applied to the lifting loop.

The bottom three examples shown in Figure 11 indicate that zig-zag stitching in several different configurations can be applied to hold the folds of the lifting loop together, whilst the upper example of Figure 11 shows that it is even possible just to apply four separate short rows of stitching at the four corners of the region of overlap of the extension end portions A and B.

It has been found that embodiments of lifting loop folded and stitched in accordance with the examples shown in Figures 10 and 11, do not suffer any substantial loss of strength from lacking the full- width stitching of the overlapped extension end portions A and B which is employed conventionally as shown in Figures 5 and 6.

It has moreover been found that these embodiments of lifting loop do not require the application of a binding sleeve 2.

The omission of the full-width stitching of Figures 5 and 6, and of the binding sleeve 2, enable the manufacture of a lift bag to be simplified, possibly leading to automation of the forming of the lifting loop. Also, an enhanced appearance can be achieved.

Claims

CLAIMS 1. A lift bag, for bulk material, formed from material having two separate extensions at the upper end of the lift bag, which two separate extensions have been connected together to provide a lifting loop of the lift bag, each separate extension comprising a layer or layers of the material of which the lift bag is formed, and the lifting loop having been formed by laying one unstitched end portion of one separate extension on an unstitched end portion of the other separate extension, then by folding the two unstitched extension end portions together at least once thereby to produce at least one fold, and then by stitching the folded extension end portions together to secure the lifting loop.
2. A lift bag according to claim 1, formed from material having four separate extensions at the upper end of the lift bag, arranged in pairs to provide two lifting loops each having been formed as aforesaid.
3. A lift bag according to claim 1 or 2, wherein prior to said stitching the two extension end portions of the or each lifting loop were folded together as aforesaid in a direction along the length of the lifting loop, thereby to produce said at least one fold extending along that same direction.
4. A lift bag according to any one of the preceding claims, wherein each said extension comprises two.or four layers of the material forming the lift bag, so that laying the end portion of one separate extension on the end portion of the associated another separate extension has provided a stack of four or eight layers of the material of which the lift bag is

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formed.
5. A lift bag according to any one of the preceding claims, wherein in the or each lifting loop the extension end portions have been folded together as aforesaid more than once, to produce a plurality of folds and a thicker lifting loop.
6. A lift bag according to any one of the preceding claims, wherein in the or each lifting loop the folded extension end portions have been stitched together by a zig-zag pattern of stitching.
7. A lift bag according to any one of claims 1 to 5, wherein in the or each lifting loop the folded extension end portions have been stitched together by four separate short rows of stitching at four corners of a region of overlap of the extension end portions.
8. A lift bag according to any one of the preceding claims, wherein the or each lifting loop, after stitching as aforesaid, was gathered-in or folded further to make it narrower ina direction transversely of the direction along the length of the lifting loop.
9. A lift bag according to any one of the preceding claims, wherein no binding sleeve is provided around the lifting loop.
10. A lift bag with a lifting loop according to any one of the variants substantially as hereinbefore described with reference to Fig. 10, or Figs. 10 and 11, of the accompanying drawings.
11. A method of forming a lift bag, for bulk material, from material providing two separate

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extensions at the upper end of the lift bag, each separate extension comprising a layer or layers of the material of which the lift bag is formed, the method comprising forming a lifting loop by laying one unstitched end portion of one separate extension on an unstitched end portion of the other separate extension, then folding the two unstitched extension end portions together at least once thereby to produce at least one fold, and then stitching the folded extension end portions together to secure the lifting loop.
12. A method of forming a lift bag according to claim 11, the lift bag being formed from material having four separate extensions at the upper end of the lift bag, and the method comprising arranging the four separate extensions in pairs to provide two lifting loops which are then each formed as aforesaid.
13. A method of forming a lift bag according to claim 11 or 12, wherein prior to said stitching the two extension end portions of the or each lifting loop are folded together as aforesaid in a direction along the length of the lifting loop, thereby to produce said at least one fold extending along that same direction.
14. A method of forming a lift bag according to any one of claims 11 to 13, wherein each said extension comprises two or four layers of the material forming the lift bag, so that laying the end portion of one separate extension on the end portion of the associated another separate extension provides a stack of four or eight layers of the material of which the lift bag is formed.
15. A method of forming a lift bag according to any one of claims 11 to 14, wherein in the or each

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lifting loop the extension end portions are folded together as aforesaid more than once, to produce a plurality of folds and a thicker lifting loop.
16. A method of forming a lift bag according to any one of claims 11 to 15, wherein in the or each lifting loop the folded extension end portions are stitched together by a zig-zag pattern of stitching.
17. A method of forming a lift bag according to any one of claims 11 to 15, wherein in the or each lifting loop the folded extension end portions are stitched together by four separate short rows of stitching at four corners of a region of overlap of the extension end portions.
18. A method of forming a lift bag according to any one of claims 11 to 17, wherein the or each lifting loop, after stitching as aforesaid, is gathered-in or folded further to make it narrower in a direction transversely of the direction along the length of the lifting loop.
19. A method of forming a lift bag according to any one of claims 11 to 18, wherein no binding sleeve is provided around the lifting loop.
20. A method of forming a lift hag with a lifting loop according to any one of the variants substantially as hereinbefore described with reference to Fig. 10, or Figs. 10 and 11, of the accompanying drawings.