CONTAINER FOR LIFTING, TRANSPORTATION AND STORAGE OF BULK MATERIAL

Abstract: A flexible container and a manufacturing process for said container, formed from a hose-like blank (1), comprising two diametrically opposite longitudinal slots or holes (6,7), and at least one intermediate slot or hole (8 and/or 9). One half (10) of the hose-like blank is inserted through the intermediate slots (8 or 9) in such way that one inner sack (10′) and one outer sack (11′) and at least one integrated lifting loop comprising material areas (15,16,17) are formed, where two of the material areas (15,16) comprise the material section (3,4) between the slots (6,7) and the intermediate slot (8) extending from the outer sack (11′) directly into the inner sack (10′) on the container's opposite side, wher­ eas the third material area (17) comprises the material section (5) between the slots (6,7) and extending in the direction from the outer sack (11′) between the two material area (15,16) and into the inner sack (10′).

Description: The present invention relates to a flexible intermediate bulk container (FIBC) for lifting, transportation and storage of bulk material. The said FIBC is formed by inserting one half 10 of a hose-like blank into the other half 11, thus forming an inner and an outer sack. The FIBC comprises a suitable common or separate bottom 3, and at least one lifting loop. The invention relates also to the manufacturing process of the flexible container. By a flexible container in the application under consideration, it is ment a container for lifting, transportation and storage of bulk material such as powderous granular fertilizer, ground or unground grain, Portland cement, coal etc. in quantities of several hundred kilos per container. It is known a sack-like container for transportation of bulk material from e.g. SE patent specification No. 420.704, where one half of the hose-like blank is inserted through a slot into the other half to form an outer- and inner sack. The middle of the hose-like blank formes in the finished product a material loop at the top section of the container. This material loop is used as a lifting eye during transportation and lifting of the flexible container. A flexible container comprising an inner and an outer bag such as described in the above mentioned SE Patent Specification has a lifting eye formed by a material loop from the inner sack, partly crossing the longitudinal axis of the container below the lifting means and continuing as an integral part of the outer sack. When the container is filled, this crossing will contribute to a contraction of the opening in the lifting eye, thus complicate the application of the lifting means to such a degree that one has to do the operation manually. The contractions of the lifting eye will be more severe if the container is filled up to maximum point. The contractions of the lifting eye increase the stress and strain of the material and thus reduce the carrying capasity of the container. To make use of the container according to the aforementioned SE Patent Specification the material loop forming the lifting eye has to be made relatively long. It involves that the ratio between the carrying capacity and the material consumption has decreased whereas the manufacturing costs have increased correspondingly. In addition, the relatively long material loop has also reduced the ability for transportation and storage of this type of flexible container in places with restricted headroom. The object of the present invention has been to make a flexible container not featuring the aforementioned disadvantages, in where; the ratio between the carrying capasity and the material consumption has increased, the manufacturing is simple and the manufacturing costs are moderate, the handling during transport and storage is simple. The scope and characterizing features of the invention are as defined in the attached claims. The special features of the said invention is that it has at least one integrated lifting loop formed by the material areas 15,16,17 which can be split into several material areas. Were two of the material areas 15,16 comprise the material section between the slots located diametrically opposite each other at the centre line of the hose-like blank, and at an intermediate slot, and reach from the outer sack directly into the inner sack. The third material area 17 comprises the material section between the diametrically opposite slots and reach from the outer sack, between the two material areas 15,16 and directly into the inner sack. This involves that the integral material sections forming the lifting loops are crossing the longitudinal axis of the container above the lifting means. The integrated lifting loops represent also a directly continuation of the walls in the outer- and inner sack, in such way that all the vertical fibres in the wall fabric carries the load of the filled container, the strain is uniformly and equally distributed to the walls in the inner and outer sack without any contraction effects or stress consentrations in the wall fabrics. These lifting loops give also lower lifting height for the FIBC. Due to the aforementioned, the degree of filling and the lifting capasity can be substantially increased compared to the container mentioned in SE Patent Specification No. 420.704. This implies that the ratio between carrying capasity and the material weight has increased and that the manufacturing costs per kilo net weight accordingly will be lower. Tests have shown that by transporting the same amount bulk-material a saving of approximately 10-20 % can be achieved in material costs by using the said invention compared to the container mentioned in SE Patent Specification No. 420.704. The scope of the invention is as defined in the independent claim 1 which describes a flexible container according to the said invention, whereas the independent claim 6 define a manufacturing process for the fabrication of one container according to the invention. The dependent claims 2-5 define a favourable design of the flexible container in accordance with claim 1. The invention will be described in more detail, by the way of example only, with reference to the accompanying drawings in which: Fig. 1 give example of the hose-like blank forming the flexible container illustrated in Fig. 5. Fig. 2 illustrates in perspective view the hose-like blank in an "inflated" state. Fig. 3 illustrates one step in the production process of the container in Fig. 5. Fig.4a,b illustrates the container in Fig. 5 seen from above, but in an enlarged version. Fig. 5 illustrates the container with the integrated lifting loops in the finished state. Fig. 1 illustrates a deflated and Fig. 2 illustrates an "inflated" hose-like blank 1 according to the invention. The hose-like blank can for example be manufactured from uncoated circular-woven polypropylene fabric or from a coated circular woven polyetylenfabric. Selection of the container fabric depends on what application and type of bulk material the container will be used for. The diameter and length of the hose-like blank should be defined depending on what volume is needed. The hose-like blank 1 has at the centre line 13 three or four longitudinal slots or holes 6,7,8 and/or 9. As it will be apparent from the following, the inner sack of the container is made by inserting one half 10 of the hose-like blank into the other half 11 through one of the slots or holes 8 or 9. The reason why there are two slots 8,9 is due to manufacturing simplicity. It is an easier operation to stamp holes in the hose-like blank when it is laid flat than doing the same operation when the hose-like blank is "inflated". The extra slot or hole 8 or 9 can be used as the opening for filling of the free flowing bulk material into the sack (see Fig. 4b). As mentioned, the simplest way to make the slots or holes is when the hose-like blank is laid flat. Fig. 1 illustrates a hose-like blank where the slots 6,7,8 and 9 are situated at the side edges and at the longitudinal axis, respectively. As it will be apparent from the following description, the material sections 3,4 and 5 between the slots/holes 6-8, between 7-8 and between 6-7, the material areas 15,16,17 form when they are joined together at least one lifting loop in the finished manufactured flexible container. The slot 9 serves in this example as an opening for filling of the container. The slots 6,7 extend from the centre line 13 between the two halves 10,11 and mainly the same distance in both directions. The lengths of these slots may vary depending on the volume, application and material choose for the flexible container. The slots or perforations 8,9 can be arranged at the central part of the hose-like blank, equivalent to slot 6,7 and may have the same length. However, it is considered to be more practical to let slots 8,9 extend from above the centre line 13 in direction of the half part 11 of the hose-like blank that represents the outer sack of the finished flexible container. The slots 8,9 can preferably be shorter than slots 6,7, e.g. half of the length. In Fig. 1 the bottom part of the hose-like blank is cut so that the ends forms starshaped flaps 14. These flaps will form the bottom of the finished container. Depending on the material, they can either be fastened by sewing or by use of glue. The construction of the bottom is not considered to be a part of the said invention, therefore it will not be discussed further. However, it should be mentioned that the construction of the bottom is not restricted to the star-shaped bottom. Various types of bottoms can be applied such as a "cross bottom" or "inserted bottom". Depending on the application, a separate or a common bottom can be used for the inner and outer sack. See the applicant's patent GB No. 1.580.576 and EP Patent Specification No. 84.110.404,5 with publication number 134 575. Fig. 3 illustrates one step in the production process of the flexible container according to the said invention. Based on the hose-like blank illustrated in Figs. 1-2, one half 10 of the blank is inserted through slot 8 and into the other half 11 as illustrated in Fig. 3, the material sections 3 and 4 between respectively slots 6-8 and 7-8 represent the two integrated material areas 15,16 extending from the outer sack 11' to the opposite side of the inner sack 10'. A third material area 17 formed by the material section 5 between slots 6-7 extending in the opposite direction from the outer sack 11′ and continuing into the inner sack between the two material areas 15 and 16. During this operation the material areas 15 and 16 are rotated approx. 180° and they extend from the inner to the outer container. Fig. 4a illustrates the said flexible container seen from above. This example illustrates a hose-like blank 1 with three slots 6,7,and 8. All three of the material areas 15,16 and 17 represent a continuation of the walls in the inner and outer sacks in such way that each and every of the vertical fibres in the wallfabric of the sacks 10′ and 11′ extend through the lifting loop and carry the load of the container when it is lifted. Thus the forces originating during lifting will distribute unformly and equally to the inner and outer sack. This represents a major advantage for this invention, and it involves that the volume can be increased without using new materials with higher strength modules and without reinforcing the container. Fig. 4b illustrates a FIBC seen from above, manufactured by a hose-like blank comprising four slots 6,7,8 and 9. This manufacturing process gives four material areas 15,16,17a and 17b. The material area 17a and 17b comprising respectively the material sections between the slots 6-7 and 7-9 are not rotated. But the material area 15 and 16 comprising respectively the material sections between slots 6-8 and 7-8 are rotated approx. 180°. By collecting the material areas 15 and 17a, respectively 15 and 17b and if desired cover them by a sleeve, one get two lifting loops. The examples described are FIBC's with three or four material areas formed by applying three or four slots, but it is evident that it is within the scope of the invention to apply more than three or four slots. The application of more slots will result in that one or more of the material areas 15,16,17 will be divided in several separate material sections. The material areas 15,16,17 can if necessary be joined in one or more lifting areas preferably including sleeves as discussed in the applicant's NO Patent Specification No. 151855. One common sleeve can respectively cover all three lifting loops or two separate sleeves can be used. Fig. 5 illustrates a finished container according to the said invention. As previously mentioned, the hose-like blank forming the flexible container will be manufactured with a suitable common or separate bottom construction 3. A separate bottom construction can for both the inner sack 10′ and the outer sack 11′, either be fastened prior to or after one half of the hose-like blank is inserted. The said invention give a simple solution to the manufacturing process of a double walled flexible container comprising intergrated lifting loops with most of the longitudinally fibres in the flexible container. These lifting loops give a container that give low lifting height, and the strain is also uniformly and equally distributed to the walls in the inner and outer sack without any contractions in the wall fabrics. All the aforementioned manufacturing steps for the flexible container according to the said invention, i.e. cutting of the hose-like blank, insertion of the half part into the other part and the production of the bottom can be achieved by use of relatively simple manufacturing equipment.

Claims: A flexible intermediate bulk container for transportation, storage and lifting of bulk material, comprising: an inner sack (10') and an outer sack (11') which are formed by inserting one half (10) of a hose-like blank (1) through a slot (8) in the central portion of the blank (1) into the other half (11) of the blank (1), a common or separate bottom construction (3) and at least one lifting loop, characterized in that the blank has in its central portion a plurality of slots (6, 7, 8, 9), two (6, 7) of them being arranged opposite each other and the slot (8) for inserting said one half (10) of the blank (1) being disposed at an intermediate position between the two opposite slots (6, 7), wherein the slots (6, 7, 8, 9) define material sections (3, 4, 5; 15, 16, 17) of the blank (1) between each other, two material sections (15, 16) are between the intermediate slot (8) and said two opposite slots (6, 7) and reach from the outer sack (11') directly into the inner sack (10') at the opposite side of the container and a third material section (5; 17) is between the two opposite slots (6, 7) and reachs in the opposite direction from the outer sack (11') between said two material sections (15, 16) and into the inner sack (10'), said material sections (15, 16, 17) thereby forming integrated lifting loops of the container. A flexible container according to claim 1, characterized in that the hose-like blank comprises four slots (6, 7, 8, 9) being manufactured by making two permeating holes in said blank being laid flat, one hole on each side of the blank's longitudinal axis (12) substantially between the longitudinal axis and the side edges of the blank. A flexible container according to claim 1, characterized in that the slots have the same length and substantially with same extension on each side of the hose-like blank's crosswise center line (13). A flexible container according to claim 1, characterized in that the hose-like blank comprises the slots (6, 7, 8, 9) being manufactured by making three holes, one (6,7) on each side edge of the hose-like blank and one hole (8, 9) at the longitudinal center line (12). A flexible container according to claim 1, characterized in that the material sections (15, 16, 17) are joined in two lifting loops including sleeves, in which one of the two sleeves covers one (15) of said two material sections and one half of the third material section (17), and the other of the two sleeves covers the other (16) of said two material sections and the other half of the third material section (17). Manufacturing process of a container according to claim 1, wherein the container is manufactured from a hose-like blank (1) by providing the blank with slots (6, 7) and a single or double bottom, characterized in that the blank is provided with two slots (6, 7) located diametrically opposite each other at the center line (13) of the blank and is provided between the two slots (6, 7) with an intermediate slot (8, 9) which can be cut through both wall fabrics of the blank after which one half (10) of the blank is inserted through the intermediate slot (8 or 9) in such a way that one inner sack (10') and one outer sack (11') and one or two integrated lifting loops are formed, the lifting loops comprising material sections (15, 16, 17) of the blank, and that the end openings of the blank are formed to at least one bottom, which can be closed before or after said one half (10) of the blank is inserted through the intermediate slot (8 or 9).

Inventors: STRAND, OLAF
Applicants: NORSK HYDRO A/S
Application year: 1989
Main classification: B65D88
IPC codes: B65D33, B65D88