EP0141429B1

EP0141429B1 - Method and apparatus for manufacture of flattened flexible containers with liners

Info

Publication number: EP0141429B1
Application number: EP84113532A
Authority: EP
Inventors: Eirik Myklebust; Bjarne Omdal; Anders Juel
Original assignee: Norsk Hydro ASA
Current assignee: Norsk Hydro ASA
Priority date: 1983-11-09
Filing date: 1984-11-09
Publication date: 1990-01-17
Anticipated expiration: 2004-11-09
Also published as: FI844396A0; PL250368A1; FI76761B; JPS60123383A; ES537377A0; AU571903B2; ATE49566T1; PT79430B; SU1604150A3; DK531584D0; DK153873B; ES286213Y; PL144288B1; PT79430A; NO834082L; EP0141429A3; ES8603774A1; BR8405699A; JPH0220510B2; NO153250B

Abstract

The present invention relates to a flattened flexible container made ready for filling with bulk material, and method and means for making a container comprising a liner of impervious sheet in an outer container of strong load-bearing material. The liner and the outer container are folded longitudinally in the same way such that the liner is kept in position by having its folds or gussets everywhere placed in the corresponding folds or gussets of the outer container. Both the liner and the outer container may have a longitudinal gusset on each side which can have a width of up to 1/8 of the container's circumference. The manufacture can be carried out in an apparatus (8) in form of a box which is open in both ends and can be folded together. Its side walls consist of longitudinal parts (7) which are connected to each other and the roof (4) and bottom (5) of the apparatus (8) by means of pliable connecting means (6). The container according to the invention can be filled with bulk material without prior inflation at the filling site.

Description

The present invention relates to a method for manufacture of flattened flexible container or intermediate bulk container according to the generic part of claim 1. Containers of that kind are ready for being filled with bulk material; the liner may consist e.g. of thermoplastic or paper.
The invention also comprises means for performing the method for manufacturing such containers.
For most applications of flexible containers it is necessary that the material to be transported is protected against being contaminated by dust, water etc., and this is usually obtained by application of an impervious liner which ideally shall be positioned against the outer container when it is filled with a material which shall be transported and/or stored. It has been found practical to place the liner in the load-carrying container already at the production site of the container. However, it has proved to be difficult to place the liner in such a way that it will not be damaged or crumpled and get a form which deviates from that of the outer container, and thereby easily bursts when it is filled with bulk material.
One way of making the above mentioned containers has been to fasten the liner to the base material for the outer container with glue or tape and thereafter finish sewing the outer container. This is labour-consuming and requires great precision in order to avoid damage of the liner during said sewing operation. Further the tapes, and thereby the liner, can be incorrectly positioned such that it will be unevenly loaded during filling and may then burst easily.
The final centration of the liner in the outer container can take place by its inflation at the filling station, for instance as described in GB Patent No. 1.475.019 (corresponding to Norwegian Patent No. 136.744). The liner will then be pressed against the outer container and be in close formation with it, presupposing that the liner originally is correctly placed and fastened to the outer container. Accordingly, this method presupposes great accuracy during placement of the liner in the outer container.
In DE No. 2.721.771 is described a container consisting of an outer load-carrying container of roundwoven material and a liner of thermoplastic sheet. According to this application the sheet is centrally placed and possibly folded during manufacture of the roundwoven base material for the load-carrying container. Cutting of suitable pieces of sheet and web, and closure of one end of the inner and outer container must then be carried out in successive steps. By this method the liner is folded by simple gusset and placed in the middle of the container, which is folded by double gusset. Thereby the folded liner will be placed between the central side fold in the double-folded outer container such that the liner is kept in place in the middle of the outer container during its further manufacture. Even though this method secures centering of the liner in the outer container, the method is limited to manufacture of outer containers made from roundwoven material. Further one will in certain cases get problems by the final placement of the liner in connection with securing close placement against the outer container, at least that part of it which shall be filled with bulk material.
FR-A-2.509.266 already shows a method of the kind described in the generic part of claim 1. The readily folded container as shown in Fig. 5 or 10 has certain advantages with respect to other known containers in that the liner with its gussets being engaged in the gussets of the outer container will maintain its general orientation in the outer container. However, the liner and the outer container are separately folded and put into each other. The finer is folded in such a way that it does not contact the inner side of the outer container at all points. Obviously, it would be too difficult to subsequently put a liner that snugly fits into the outer container into this container. The known method therefor is complicated and it does not ensure that the liner is supported by the outer container everywhere when it is filled so that particularly liners of thin material can tear, as is explained in the description.
It is therefore one object of the present invention to arrive at a method for manufacture of flattened flexible containers which is easily to perform and which provides containers which when inflated or filled will have a liner with the same form as the outer container and where the liner everywhere lies closely against corresponding points of the outer container, at least that part of the container which shall be filled with bulk material, without using fastening means as tape etc., and that crumpling of the container is avoided.
A further object was to arrive at means for performing the above method, i.e. for correct placement of the liner in the outer container at the production site and thereby be able to manufacture a product which is completed as far as possible there.
The most important problems experienced with flexible containers, proved to be caused by incorrect placement and fastening of the liner at the production site. The inventors therefore tried to change the method of placing the liner in the outer container and a way of fastening the liner or keeping it in place in the outer container. Obviously, it is no help in placing the liner correctly at the beginning if it is displaced before or during the filling operation. In order to avoid penetration and fastening by securing the liner to the outer container if it is displaced or incorrectly placed, the container can of course be readymade before the liner is placed in it. The problem will then be to place the liner correctly in the outer container in a rational way and such that it is not crumpled during filling of bulk.material and thereby can be damaged.
To start with the inventors chose to direct their effort on placing the liner in the outer container after the latter had been joined together. It was found that placement of the liner could be carried out in a simple way and that it also could be locked in a centered position in the outer container without using glue or tape. The operation of placing and fastening the liner would thereby be simpler than by previously used methods. In addition one obtained a product consisting of a load-carrying outer container and a protecting liner of impervious material which was simpler, faster and more secure to fill with bulk material than previously known containers where the liner was fastened to the outer container by tape or the like. It was found that if the liner was placed in an outer container and folded lengthwise with the same type of gusset as the outer container, the liner would be kept in place by the gusset orfold of the outer container. Further would those points of the liner which are opposite and against corresponding points in the outer container when it was inflated or filled also be opposite each other when the two containers were folded together. By this way of manufacturing the container one obtained all the above advantages.
Manufacture of such a product can be carried out in several ways and will to a certain degree depend on whether the outer container is made from flatwoven or roundwoven base material. Primarily the liner and the outer container are folded with gusset lengthwise in the same way such that the liner's gusset is kept in place by the outer container's gusset when the containers are flattened and that corresponding points lie against each other such as stated above.
The inventors found a suitable way of obtaining the new product by placing the liner in the finished outer container which then was inflated. This was carried out in a special way, i.e. by first placing the container in some folding means in form of a tunnel or box having squarish cross-section and then inflated. The longitudinal side walls were divided in two and joined together by hinges or the like. Subsequent to inflation the box was pressed together, and during this operation the hinged side walls formed gussets in both the liner and the outer container. The containers were pressed together and could then be drawn out of the box, and optionally they could be folded crosswise of the longitudinal direction and were then ready for transport to the filling site for bulk material.
Aflexible container made in accordance with the method of the invention can be connected to a filling apparatus and bulk material can be filled directly into it without prior inflation. For some types of bulk material inflation of the container at the filling site can be practical for other reasons than adjustment of the linerto the outer container. The invention is as defined in Claims 1 and 3.
The invention will be further explained in connection with the description of the figures and an example.

Figure 1 shows a cross-section of the folding apparatus with the container in inflated form.
Figure 2 shows the folding apparatus with the inflated container viewed from the side.
Figure 3 shows a cross-section of the liner and outer container partly folded together in a folding apparatus.
Figure 4 shows a cross-section of the folding apparatus with the container completely pressed together.

In figure 1 is shown a folding apparatus (8) in form of a squarish box or tunnel being open in both ends. The cross-section of the apparatus (8) can of course deviate from the squarish form. It can for instance be rectangular or its walls (7), roof (4) and bottom (5) can be slightly curved.
The apparatus (8) can be folded together as its side walls consist of at least two longitudinal parts (7) which are connected to each other and the roof (4) and the bottom (5) by means of pliable joining means (6) which can be hinges, flexible tapes or the like.
The method of the invention can be carried out by first placing a liner (2) in a completed outer container (1) which can be equipped with lifting grip (3). Both the liner and the container are then placed in the apparatus (8) and air is blown into the liner (2) and pressing it against the outer container (1) such that it touches the walls (7), roof (4) and bottom (5) of the apparatus (8). In order to show that one has two containers, the liner or inner container (2) is shown on the figure at a certain distance from the outer container (1), while in practice the two containers will lie closely against each other when they are inflated.
In figure 2 there is a side view of the apparatus (8), and one will notice parts of the containers outside the apparatus (8) such that one can get hold of the lifting grip (3).
In figure 3 the apparatus (8) is partly pressed together as the roof (4) is pressed against the bottom (5), and the joining means (6) of the side walls (7) are pressed against the centre of the apparatus (8). During this pressing operation both containers (1 and 2) are exposed to a certain air pressure at the same time as air can get out corresponding to lowering the roof (4) against the bottom (5). Hereby one obtains that both containers are folded in the same way and that the liner (2) all the time and all over is pressed against the outer container (1).
In figure 4 the apparatus (8) is shown after having been pressed completely together, and both containers are folded in the same way. In order to clearly visualize how the containers are folded, the roof (4) and the bottom (5) of the apparatus (8) are drawn in an artificially large distance from each other. The folds of the liner (2) lie in the corresponding folds of the outer container (1). As can be seen from figures 3 and 4 the width of the gussets will be about 1/4 of the flat laid width of the container, i.e. about 1/8 of the container's circumference. By applying such deep gussets one obtains both that the liner is kept securely in place in correct position in the outer container and that corresponding points in the two containers lie across each other such as they shall when the containers are inflated or filled with bulk material. The containers can now be drawn out of the apparatus (8) in folded form by using the lifting grip (3). The containers can then be folded together one or several times and will then be ready for transport to the filling site for bulk material.
The container manufactured according to the method of invention can also be made in other ways than the one described above. The essential features of the manufacture are defined in Claim 1. This is obtained by inflating the containers before both containers are folded. One can for instance first place the liner in on the outer side of a rack or the like having the same form as the cross-section of the apparatus (8) shown in figure 3. Thereupon the outer container can be placed over the liner and the liner and the apparatus pressed together against the inflation pressure till one gets a folded two-gusset flexible container. In order to use this method the containers must be open in one end. During manufacture from material for double-gusset flexible containers, one will principally carry out the method in a similar way by round-weaving the outer container around the continuous hose of the liner and then place the two base materials in on a folding apparatus such that the base material for the liner and the outer container are folded lengthwise in the same way and that the base material for the liner is kept in place as its folds or gussets lie in the corresponding folds or gussets in the outer container's base material. Base materials manufactured in this way can then be cut up in suitable pieces and joined together in at least one of their open ends by forming bottom and lifting loops.
The present invention provides a method for producing a container into which bulk material can be filled without prior inflation at the filling site and without damaging the liner. This leads then to less rejection of containers and totally faster filling of the containers. One also avoids that the liner forms pockets which can not be utilized. Already from the moment the liner and the outer container are folded and until they are filled with bulk material they will be in such relative position which they shall have when filled.
The inventors also arrived at a method for manufacturing the product with an apparatus which both by itself is rational and which in addition simplified the whole process from manufacture of the flexible container till it is filled with bulk material and is ready for further transport to storage or application.

Claims

1. Method for manufacture of flattened flexible containers comprising a liner (2) of impervious sheet in an outer container (1) of strong load carrying material; where the liner (2) and the outer container (1) are folded lengthwise in the same way such that the liner (2) has its gussets placed in the corresponding gussets of the outer container (1), characterized in that

the liner (2) is placed in an outer container (1),

the liner (2) is inflated, both the outer container (1) and the liner (2) are simultaneously folded for making corresponding longitudinal gussets therein keeping up a certain over-pressure in the liner such that the liner's (2) gussets are everywhere positioned in the outer container's (1) gussets.

2. Method according to claim 1, characterized in that after the liner (2) has been placed inside the outer container (1) both the outer container (1) and the liner (2) are placed in a collapsible box or tunnel (8) having two opposing side walls (7, 7) divided in the middle and hinged together, and that the liner (2) and the container (1) are then inflated, whereupon the side walls (roof 4, bottom 5) connecting said two opposing side walls (7, 7) are pressed together while simultaneously the centre lines of said opposing side walls (7, 7) are pressed towards each other and then the thereby folded outer container (1) and liner (2) are pulled out of the box (8).

3. Means for performing the method according to any of claims 1 and 2, characterized in that said means consist of a collapsible box or tunnel (8) which can be open at the two ends corresponding to the respective upper and lower end of the flexible container and which has one set of two opposing side walls (7, 7) each consisting of at least two longitudinal parts (7) which are connected to each other and to an adjacent side wall (roof 4, bottom 5) by means of pliable connecting means (6).