WO1989007561A1

WO1989007561A1 - A flexible receptacle

Info

Publication number: WO1989007561A1
Application number: PCT/FI1989/000031
Authority: WO
Inventors: Christian Wiklund
Original assignee: Oy Fluid-Bag Ab
Priority date: 1988-02-19
Filing date: 1989-02-17
Publication date: 1989-08-24
Also published as: FI87913C; JPH03503517A; FI880789A; AU3185389A; FI880789A0; JP2713485B2; FI87913B

Abstract

The invention relates to a flexible receptacle comprising a cylindrical support portion (1) consisting of two layers (2, 3) manufactured of a hose material and an inner portion (4) within the support portion. In case of inner stresses in known receptacles, those warp threads of the support portion break first which are situated in inward bends of the inner layer (3) of the support portion at the ends, because these threads can be pushed into outward bends of the outer layer (2). This can be prevented, if a levelling course (12) is placed between the layers (2, 3) of the support portion at the ends of the receptacle.

Description

A flexible receptacle

The present invention relates to a flexible re¬ ceptacle comprising a substantially cylindrical sup- port portion with a mantle and two ends and manufac¬ tured of a woven hose fabric, an inner portion of a flexible film within the support portion, against which the inner portion bears, and valves in the middle of the ends of the receptacle for filling and emptying the receptacle, the fabric of the support portion being double-folded at the valves to form at least two fabric layers in the support portion.

Flexible receptacles of this kind are previously known. They are usually manufactured in sizes of 500... 1500 litres and they are meant for transportation of liquid chemicals, glue, wine, juice and the like. Receptacles are usually mounted on a pallet in such a way that the centre axis is perpendicular to the pallet. The inner portion of the receptacle is intended to be disposable and it is therefore manufactured of a film as thin and cheap as possible. The support portion receiving all the stresses shall have a good strength.

The support portion is manufactured of a hose, which is double-folded around rings at the ends of the receptacle, and therefore, the support portion usually consists of two layers on each other. The material is preferably a woven plastic fabric. Because the material is contracted at the ends of the receptacle, wrinkles or folds are formed at the ends of the receptacle, the depths of which wrinkles or folds increase in the di¬ rection from the mantle of the receptacle towards its centre line.

When the receptacle e.g. due to shocks is sub¬ jected to inner loads exceeding the strength of the support portion, the first breaks are often formed at the ends of the receptacle. Investigations have shown that the warp threads extending in the longitudinal direction of the receptacle in the support portion break first, which threads extend along the bottom of the folds, i.e. nearest the centre line of the recep¬ tacle. This may depend on that these warp threads extend a shorter distance between the end rings than the warp threads located farther away. Thus they are in a sense shorter. Another problem caused by the formation of folds consists of that the film of the inner portion is in case of shock-like inner load peaks pressed into the folds of the inner layer of the support portion, which can lead to a broken film. The object of the present invention is to pro¬ vide a flexible receptacle with an improved strength at the ends. The receptacle is characterized by a levelling course between the fabric layers of the support portion at the ends of the receptacle. An improvement in the strength of the ends is reached unexpectedly by placing a material layer, here called a levelling course, between the layers of the support portion, which improvement is considerably greater than the improvement which can usually be ex- pected when the number of layers of the receptacle is increased. Why it is so, is not quite clear, but the following reasoning may hold good. It has turned out that the folds of the support portion are distributed in such a way that right before an inward bend towards the centre of the receptacle in the inner layer there is always an outward bend in the outer layer. Conse¬ quently, the warp threads in the inward bend can in case of a sudden inner load be displaced a relatively long distance outwards down to the bottom of the outward bends. This displacement causes a stretching of the warp threads often leading to the fact that the threads break before they reach the bottom of the outward bends. A levelling course between the layers of the support por- tion prevents these warp threads from being displaced into the outward bends and thus reduces the peak load the threads are subjected to.

In principle, this is the case also with the film of the inner portion. Because the folds in the inner layer of the support portion cannot extend into the outward bends of the outer layer any more, but only to the middle plane of the support portion, the folds produced at shock peaks are not so deep as earlier and therefore, there is a smaller risk of breaking the film than in known receptacles. The material layer between the layers of the support portion thus has a levelling effect on the support portion.

The positive effect of the levelling course is particularly great, if the course is more rigid than the fabric of the support portion. Hereby it is pre¬ ferable that the levelling course consists of a woven fabric with a higher rigidity and density than the fabric of the support portion, preferably approximately 200 g/m². The levelling course consists in its simplest form of a circular piece of material with an opening for the valve and with a diameter substantially cor¬ responding to the diameter of the end. Its function has proved to be best, if it lies loose between the layers of the support portion.

A preferable embodiment of the receptacle of the invention is described in closer detail in the fol¬ lowing with reference to the drawing enclosed, in which Figure 1 shows a side view and a partial section view of the receptacle of the invention.

Figure 2 shows a section view of a detail of the receptacle along a radial line and

Figure 3 shows a section view of a detail on a large scale along a peripheral line around the upper valve.

The receptacle shown in Figure 1 comprises a substantially cylindrical support portion 1 manufactured of two layers 2 and 3 of a woven plastic fabric and an inner portion 4 manufactured of a flexible plastic film within the support portion, against which the inner portion bears. The mantle and the lower end of the support portion is enclosed by an outer bag 5 provided with pockets 6, into which are inserted legs 7. These legs are fastened to a pallet 8, on which the receptacle is arranged. In the middle of the ends there are valves 9, of which the upper valve is shown.

The support portion consists of a hose fabric double-folded around a ring 10 indicating the valves. Because the hose in free state has the same diameter along its whole length, the contraction at the ring 10 causes folds 11 in both layers 2, 3 at the ends. The depth of the folds increases continuously from the mantle towards the valve 9 situated on the centre line of the receptacle.

In accordance with the invention, a levelling course 12 is arranged at the end of the receptacle between the layers 2, 3 of the support portion. The course 12 is relatively rigid in comparison with the layers of the support portion and consists for instance of a woven fabric with a higher density than the fabric of the support portion has, e.g. appr. 200 g/m². In the shown embodiment, the levelling course consists of a circular piece of material with an opening for the valve and with a diameter substantially corresponding to the diameter of the end. The course lies loose between the layers 2, 3 of the support portion, and on account of this and its rigidity, it does not extend into the folds 11 of the support portion, but its form corresponds substantially to the principal plane of the end.

In Figure 3, the formation of folds in the vi¬ cinity of the ring 10 is seen. A warp thread, i.e. a thread running in the longitudinal direction of the hose of the support portion, is indicated by the ref¬ erence numeral 13. Because the warp thread is situated in an inward bend 14 in the inner layer 3, it lies in an outward bend 15 in the outer layer 2, because all warp threads are equally long. The plane levelling course 12 lies between the layers.

When the receptacle is subjected e.g. to a shock causing a suddenly increasing pressure outwards, towards the end of the receptacle, the inner portion 4 and the inner layer 3 of the support portion are pressed outwards. If there were no levelling course 12, the inner portion of the warp thread 13 would hereby possibly be pressed outwards to the bottom of the out¬ ward bend 15, i.e. against the outer portion of the warp thread. The stresses on the inner portion could hereby grow so great that it breaks. On account of the level¬ ling course 12, the outward motion of the warp thread is, however, stopped in the middle plane of the support portion, which restricts the stresses on the thread. Test results from drop tests with different drop heights and different types of receptacles are stated in the following. In the table, al indicates a receptacle with axial twisting at the ends according to the Finnish Patent 70691 without levelling course at the end a2 indicates the same as al, but with levelling course at the end bl indicates a receptacle without axial twisting at the ends and without levelling course b2 indicates the same as bl, but with levelling course

Differing from the above, the levelling course can have a diameter corresponding to appr. 2/3 of the diameter of the end, because the folds are deepest nearest to the valves. The course can be fastened to the support portion or to the ring 10 and the course material can differ from that presented above. The support portion can consist of more than two layers.

Claims

Claims :

1. A flexible receptacle comprising a substan¬ tially cylindrical support portion (1) with a mantle and two ends and manufactured of a woven hose fabric, an inner portion (4) of a flexible film within the support portion, against which the inner portion bears, and valves ( ) in the middle of the ends of the recep¬ tacle for filling and emptying the receptacle, the fabric of the support portion (1) being double-folded at the valves to form at least two fabric layers (2, 3) in the support portion, c h a r a c t e r i z e d by a levelling course (12) between the fabric layers (2, 3) of the support portion at the ends of the receptacle.

2. A flexible receptacle according to claim 1, c h a r a c t e r i z e d in that the levelling course (12) consists of a woven fabric with higher rigidity and density than the fabric (2, 3) of the support por- tion has, preferably appr. 200 g/m².

3. A flexible receptacle according to claim 1, c h a r a c t e r i z e d in that the levelling course (12) consists of a circular piece of material with an opening for the valve (9) and with a diameter substan- tially corresponding to the diameter of the end.

4. A flexible receptacle according to claim 1, c h a r a c t e r i z e d in that the levelling course (12) lies loose between the layers (2, 3) of the support portion.

5. A flexible receptacle according to claim 1, c h a r a c t e r i z e d in that the shape of the levelling course (12) corresponds to the principal plane of the end.