FI69436B - FLEXIBLE BEHAOLLARE FOER TRAMSPORT OCH LAGRING AV MASSGODS OCHFOERFARANDE FOER DESS FRAMSTAELLNING - Google Patents

Description

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The present invention relates to a flexible container for the transport and storage of bulk goods, in particular for powdered or granular material. The invention also comprises a method of making such a container.

The tank includes combined lifting loops, a filling opening, a middle part and a bottom part. The tank can be equipped with 10 inner, impermeable liners.

Today, there are several variations of flexible containers of the above type. For containers with combined lifting loops, reference is made to Applicant's GB Patent 1,475,019 and U.S. Patent 4,136,723. The flexible containers of these patents are preferably made of a single piece of woven material, e.g., flat woven or round woven polypropylene.

According to the former patent, the lifting loops 20 of the container are formed from a double piece of material in the form of a closed loop, which is a continuous, uniform extension to the piece forming the container itself. The total length of the lifting loops is substantially equal to the circumference of the container. The bottom of the container is formed by joining the lower part of said piece of material together. According to the US patent, several strips are formed in the lower part of the material and by connecting these together in a special way a double base is formed.

The latter patent also relates to a flexible container made of a circular fabric material, in which the height direction of the container coincides with the longitudinal direction of the material. In this case, the top of the container is joined together or closed by tying and lifted by a compression hook, a belt with a movable knot, etc., whereby its lifting strength decreases when the strength of the material can no longer be used to the maximum when lifting the container.

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The above-mentioned flexible containers have gained widespread use, e.g. due to their simple structure, which at the same time offers high strength, because the strength of the material itself can be used to the maximum in the horizontal or vertical direction, but only in one direction at a time. When such a container is made of a circular woven material, it also has substantially higher strength in the horizontal direction along the circumference of the container than containers having one or more side seams in their longitudinal direction, but the lifting strength remains lower than containers made of flat woven material.

However, there are special strength requirements for some applications. Thus, it is required 15 that tanks intended for the transport of dangerous goods withstand a drop from a given height to a flat floor or the like without tearing. The tank must be subjected to a so-called drop test if it will be used for the transport or storage of such bulk material. During the drop test 20, the lower part of the flexible container is subjected to a very high stress around its circumference, because a radial burst effect is created perpendicular to the vertical axis of the container when this drop test is performed on the container. In the following text, this area is referred to as the burst zone, which can generally extend from the bottom of the tank upwards to halfway between its height when filled. How much of the tank is subjected to this additional stress depends on the properties of the material being transported.

Tanks that are too weak will rupture in the burst zone-30 when subjected to a drop test. Flexible containers with one or more side seams generally have lower strength in the burst zone than containers made of round woven material because the strength of the base material decreases around the side seams. However, it is possible to make these containers that meet the requirements of the drop test by oversizing the properties of the material used to make the container 3 69436, but such a large oversizing is not particularly economical.

It is known from Applicant's NO Patent 143,399 to place a cylindrical or circularly woven piece of material 5 on a container with side seams for reinforcement in order to obtain an acceptable result in a drop test. However, placing a cylindrical piece of material around the container requires extra work. Such a belt can also cause problems when emptying the tank.

It is an object of the present invention to provide an improved flexible container having combined lifting loops and a cylindrical portion which would withstand the stress applied to the burst-double zone of the container in a drop test. At the same time, the tank should have a high lifting strength and a strong base structure to distribute the stress on the tank in an advantageous manner.

It is a further object of the invention to provide a structure which would allow the use of a circular woven material, since it has certain advantages, e.g. in connection with manufacture.

The inventors first looked at the relative importance of the advantages and disadvantages of known flexible tanks to determine which properties should be improved and whether this could be done without sacrificing the good properties of the tanks. One of the main advantages of the above-mentioned tank with combined lifting loops is their high lifting strength. It was now surprisingly found that by making the container in a special way from the cylindrical material 30, a container with a high strength in the purs-double zone could be obtained, while having lifting loops with a sufficiently high tensile strength.

The flexible container according to the invention was made of a cylindrical material which was cut at one end so that the main part of the cut deviated from the longitudinal and transverse direction of the material, i.e. from the warp and weft direction of the woven material. The cylindrical piece of material was folded in the transverse direction and the cutting edges were joined together, e.g. by sealing, so as to form a container with connected lifting loops at its top and a cylindrical part between the lifting loops and the bottom, formed in a manner known per se. 136 723.

The most important feature of the flexible container according to the invention is the way in which it is joined together to form lifting loops and to connect them to the cylindrical part of the container. The joints are characterized in that they form an angle x with the longitudinal direction of the cylindrical material (warp direction of the woven material). It was found that the angle x should be between 0-90 °, where x = 0 ° 15 corresponds to a container with one or more side seams and x = 90 ° corresponds to a container with one or more joints transverse to the longitudinal direction of the material, e.g. the lifting loops. The lifting strength of the container decreases, corresponding to the difference in strength between the woven material and the joints. The strength of the material normally decreases by a tension of 50-70% transverse to the joint direction when the woven material has a seam. By selecting an angle x less than 90 °, the length of the joints is increased, so that deterioration due to cutting and re-joining of the material can be prevented.

Using an angle x 0 45 ° thus gives the joint a length which is about 40% longer than when x = 90 °, if the seam has a V-shape between the edges of the lifting loop. Assuming that the strength of the joints is 60%, a total strength of 60 x 1.4 = 84% could be expected for the container according to the invention. Since the joints can hardly have exactly the same elastic properties as the material and the forces applied to the joints are not perpendicular to them, shear forces are generated which can somewhat reduce the strength achieved over a longer length of joints so that strength can be expected from the container according to the invention. , which is between the strengths of tanks with x = 90 ° (connected lifting eyes) and tanks with x = 0 ° (joints on the sides of the tank).

The special features of the invention are defined in the appended claims.

The structure of the flexible container and the method of making the same will be described in more detail below with reference to the drawings, in which Fig. 1 shows a base material for making two flexible containers, Fig. 2 shows one of the basic pieces basic body 15, Fig. 4 shows the base body in an inventive and pre-cut, Fig. 5 shows the folding of the base body of Fig. 4, Fig. 6 shows the base body of Fig. 4 inverted transversely, Fig. 7 is a three-dimensional drawing of a container made of the base body of Fig. an alternative method of cutting the base body to make flexible containers. Figure 1 shows two circularly woven base pieces (1) of cylindrical material cut along lines a, a'b'b and in which the cut lines a, a 'and b'b form angles x with a warp of circular woven material. In contrast, the cut lines a'-b 'follow the warp direction of the material 30. The base body (1) can be cut transversely to the fold line (2) for a central filling opening (3). The cuts (4) make it possible to form a double base, as described in U.S. Pat. No. 4,136,723. 69436 presented. The base body (1) is then folded over the fold line (2) as far as necessary so that the joints a, a 'cover the lines b, b' and the lifting loops (5) are obtained. The lowest point (B) in the V-shaped joint 5 (8) is preferably located above the burst zone (9), as shown in Figure 3. The extremities of the V-joint are marked (B '). The joints may be made by sealing, gluing, fusing the joints together or in another suitable manner. The bottom of the tank is made in a manner known per se.

The container can also be manufactured in such a way that the cutting line a'-b 'is equal to O, i.e. the piece of material (1) is cut directly from a to bthen. The joints then extend to the upper part of the lifting openings (5) and the base body 15 (1) must be cut to the length of the lifting loop.

The container can also be manufactured by extending the shear lines a'-b 'beyond the intersection of a, b' and b, b ', as shown by the broken lines (11) in Fig. 1, to enlarge the opening (6) and thus the lifting loops.

The container can also be made with reduced lifting loop openings (6) by extending the joints a ', b' (Fig. 2) and a ", b" (Fig. (6) in the direction of the fold line (2) so as to obtain side seams in the container to the top of the middle.

The container can also be made so that the section lines a, a ', b, b' consist of curves or combined section sections which form a different angle with the longitudinal direction of the material than the angle x, provided that the connecting line of the starting and ending points of the section lines forms 30 bases (1 ) with the longitudinal direction, the angle x and the section line substantially overlap when they are over the fold line (2).

Fig. 4 shows a basic body of round woven material folded twice as shown in Fig. 35 5 along the fold lines (10). This piece of material is then cut in the same way as shown in Fig. 7 69436. When the base piece (1) is turned open again / when cut along the lines a, a ', b, b', it becomes in the shape shown in Fig. 6. When the strips above the or-line (2) are folded over it 5 and joined along the intersecting lines, a W-shaped joint line (8) with extremes (B ") and lowest points (B) is obtained. Fig. 7 shows a container made in Fig. 4 and having connecting lines (8) for forming the lifting loops (5) As can be seen from Fig. 7 10, this container does not have a central filling opening. avoid.

By making a flexible container in this way, seams (8) of the same length as the V-shape are obtained, but the lowest point (B) of the seam (8) does not extend as low as the cylindrical part (12) and there is no risk of the seam (8) entering the burst zone. .

As shown in Fig. 8, the flexible container can also be made in such a way that the line a'-b 'is cut upwards in the base body, whereby both parts of the section lines a, b' and b, 'are located on each side of the fold line (2).

The joint (8) is then on each side of the lifting loop (5) so that the lowest point (B) or (B ', B ”) of the seam (8) does not extend so low into the cylindrical part (12) that there is a danger of the joint (8) into the eruption zone (9).

By changing the length of the line a'-b ', the lowest point (B) can be kept at a constant height above the base (7) in such tanks by changing the length to width ratio when using V- or W-shaped joints (8) with a constant angle x.

It has been found advantageous to make the container with joints (8) in which the angles x are in the range of 30-60 ° 35 and the lowest point (B) of the joints is located halfway up the height of the container when filled. However, the entire joint 8 69436 should preferably be located above the burst zone (9). However, the invention is not limited to these values, because e.g. the fluidity of the tank filling material affects the location of the largest burst effect in the drop test.

5 The fluidity also affects the angle formed by the walls of the tank with the vertical center line of the tank when the tank is lifted from its lifting loops attached to the lifting hook. The distribution of tension in the flexible container thus depends on the quality of the filling material 10. Therefore, it is preferable to perform the fitting according to the fluidity of the material to be transported in the container.

To determine the strength of the container according to the invention in relation to known containers, some 15 comparative experiments were performed. The flexible containers I and II according to the applicant's U.S. Patent 4,135,723, with an angle x = 0 °, the flexible containers li and IV, where x = 90 °, and the flexible containers V-VIII according to the invention, where x = 40 °, were filled 650 kgrlu of flowing material and were subjected to a static elongation test until rupture.

Tanks III-VIII were made of circular woven material and tanks I-II were made of planar weaving material, all of which consisted of 170 tex polypropylene yarns of 34 yarns per 10 cm in both the warp and weft directions. All test containers were made to the same size with the same number of wires in the longitudinal direction of the container and the base structure according to the above-mentioned US patent. To compare the test results, the results of the flexible container the tensile strength for the two tanks of each type is given below.

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Table 1 χ Traction Average Strength%

5 Tank kN kN

I 0 ° 42.4 43.95 100% II __Of__45.5 ___ III 90 ° 24.4 23.35 53% 10 IV__90 £ __20.3 ___ V _ ~ 50 ° __34.5_ 33.55 76% VI _ ~ 50 ° __32.6 ___ VII _ <* 50 ° __33.3_ 37.45 85% 15 VIII_U50 ° 36.6 ____

As can be seen from the table, the lifting strength of tanks with lifting loops fixed at 20 x = 90 ° (tanks III and IV) is almost half (53%) due to the seams, and this was also expected. Containers V and VI according to the invention, on the other hand, can be subjected to a tension of 76% of the value which a container can withstand without a seam in its lifting loops.

25 Tanks VII and VIII are of the same type as V and VI, but their joints have different elastic properties. On average, these can be exposed to 85% stress. It can be clearly seen from the experiments that the new structure makes it possible to subject the filled container 3Q according to the invention to higher tensile forces than flexible containers with sewn lifting loops (x = 90 °), while on the other hand it can be subjected to less tension than the container with combined lifting loops and side seams. (x = 0 °) (tanks I and II), but close to it.

Drop tests were then performed on tanks corresponding to tanks I-VIII. The tanks were also filled with 10,694 36 now 650 kg of flowing material and subjected to drop tests at heights of 50 cm and 80 cm. The rupture of the tank in the test is indicated in the table by the word YES.

When it survives the test without tearing, it is reported with the word NO.

Table 2 10 x Drop height Tank --- _ 50 cm__80 cm_ I 0 ° yes yes II __0 ° yes__yes 15 III 90 ° no no IV __9QQ no__ no_ V rw50 ° no no VI __ / * 50 ° no____ no_ VII ^ v50 ° no no VIII <v50O no no 20 L___LI_

As can be seen from the table, the previously known tanks I and II tear at their side seams already at a drop height of less than 50 cm, while the slender tanks III and IV with sewn lifting loops and x = 90 ° and the flexible tanks V-VIII according to the invention can withstand at least 80 cm high on a solid surface or floor without tearing.

Experiments show that the filled flexible container according to the invention has a high tensile strength because it can be exposed to stresses very close to the value that a seamless (x = 0 °) flexible container with combined lifting loops can withstand and at the same time withstand the same stresses in a drop test. as a flexible container made of non-cylindrical material with sewn-on lifting loops and x = 90 °.

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The flexible container according to the invention not only combines the requirements of high tensile strength and high strength in the burst zone, but is also easy to manufacture and does not require more material 5 than the containers with which it has been compared here. A new container has also been provided which has a high lifting strength and whose burst zone strength meets the requirements of the drop test.

Claims (10)

1. Flexible container (1) for transporting and storing bulk goods and comprising lifting loops (5), a filling opening (3 or 6), a central part (12) and a bottom section (7) as an indivisible whole; characterized in that the container consists of a hose-shaped piece of material, the upper part of which is joined to the central part (12) by means of joints (8), which form an angle x 10 with the longitudinal direction of the hose-shaped material, where x lies between 0 ° < x <90 °, and that the lower part of the tubular material is joined in a manner known per se for forming the bottom section (7). Flexible container according to claim 1, characterized in that the joints (8) are in the form of a V or W, wherein the lowest point (B) is preferably above the burst zone (9), which forms the part of the container which is subjected to the greatest loading pressure when a filled container is subjected to a vertical fall against a flat surface. Flexible container according to claims 1 and 2, characterized in that the joints (8) form an angle of 30 ° <x <60 ° with the longitudinal direction of the tubular material piece and that the outermost points B *, B ") of the joints are located at the lower edge of the side opening (6) of the lifting loops (5). Flexible container according to claims 1 and 2, characterized in that the outermost points (B ', B ") of the joints (8) are located above the lower edge of the side openings (6) for the lifting loops (5). Process for producing flexible containers according to claims 1-5, characterized in that a hose-shaped piece of material is laid flat, possibly first after having been folded at least one thread longitudinally, 69436 after which it is cut into two symmetric pieces (1). cutting line a, a ', b', b, where lines a, a ', b', b form an angle of 0 ° <x <90 ° with the longitudinal axis of the piece of material and line a'-b1, which is greater than or equal to with 0, 5 forms a vertical line parallel to said axis and located in the center of the piece of material (1) on each side of a fold line (2), and the upper part of the cut piece of material (1) is folded over the line (2), after which this upper part is closed by means of a joint (8) along the cutting lines for forming lifting loops (5) and the lower part of the material piece (1) is closed in a manner known per se. 6. A method according to claim 5, characterized in that in the material piece (1) incisions are made for a central filling opening (3) and incisions (4) in the lower part for forming flaps for producing a double bottom ( 7). 7. A method according to claims 5 and 6, characterized in that a hose-shaped piece of material (1) is first folded twice along fold lines (10), after which two symmetrical measuring pieces (1) are cut along a cutting line a, a '. , b ', b, after which the piece of material (1) is unfolded and its upper part is folded over the line (2) and is joined with the central part (12) in a W-shaped joint (8). 25 8. A method according to claims 5-7, characterized in that, when cutting the piece of material (1), the lines a'-b 'are formed, which have a length corresponding to two times the length of the side opening (6). 9. A method according to claims 5-7, characterized in that the material piece (1) is formed such that the line a'-b 'is less than two times the length of the opening (6) and that a cut ( 11) is made in the extension of this line to achieve the desired length of the openings (6). 35 A method according to claims 5-7, characterized in -