TECHNICAL FIELD

[0001] The present invention relates to a method for emptying a flexible container according to the preamble of claim 1. In particular, such a method is used for emptying a flexible transport bag or intermediate bulk container (what is called an IBC) of a viscous material stored therein.

[0002] The present invention also relates to an emptying apparatus of the type presented in the preamble of claim 6. Such an apparatus is used for emptying a flexible container, particularly a transport bag, of viscous material stored therein, preferably through a bottom opening comprised by the container of formed therein.

PRIOR ART

[0003] It is generally known to transport viscous material, i.e. material with high viscosity, in different containers of fixed or variable form. These containers may be formed of barrels or bags made of different materials or material combinations.

[0004] Since it is not often that the container can be emptied of the transported material without auxiliary means, mangle and pump arrangements of various types and combinations thereof have been provided.

[0005] There are a number of examples of mangle apparatuses on the market. An apparatus like this is illustrated in this context by European patent EP 1 625 093. The apparatus comprises two parallel rollers arranged to be positioned against opposite walls of a flexible bag-like container. By pressing the rollers against each other and, at the same time, moving them in a direction towards the bottom opening of the container along an imaginary vertical axis, the viscous material can be pressed out of the flexible container relatively well.

[0006] Unfortunately, the emptying apparatuses used today have turned out to share the same problems. Some of the viscous material to be emptied from the container often remains along the walls of the container and along the walls of the discharge pipe. Generally, it is calculated that the residual material that the user cannot make use of constitutes 1 to 3% of the total amount of transported material. The economic significance of the material residues is thus great, and there have been attempts at several different solutions for minimizing the residue percentage in the emptying of containers. [0007] To improve emptying, there have been attempts to, for example, use pumps which are connected to the discharge pipe of the container and usually pre-mounted at the lower end of the container. With these pump arrangements, the material can be sucked out of the container relatively easily. Unfortunately, it is often necessary to interrupt the emptying before the container is successfully emptied completely. This is necessary to prevent air bubbles or air pockets from being formed in the material flow.

PRESENTATION OF THE PROBLEM

[0008] By means of the present invention, the problems of the known solutions can be substantially avoided, thus achieving improved emptying of flexible containers.

[0009] This task is solved according to the invention by providing the method for emptying a flexible container according to the invention with the characterizing features of claim 1. The emptying apparatus of the invention for emptying a flexible container is, on the other hand, provided with the characterizing features of claim 6. The following corresponding dependent claims disclose suitable further developments and variations of the invention, further improving the functioning of the invention.

[0010] In the following description, the terms "up", "down", "above", "below" etc. denote directions in relation to the emptying apparatus for emptying a flexible container or its structural details as they are shown in the appended figures.

[0011] By means of the method and apparatus described in the present invention, several significant advantages are achieved, compared with the prior art. Thus, nearly complete emptying of flexible containers can be achieved with relatively simple structural solutions. Besides, this result can be obtained without having to use any pump devices in emptying, which considerably simplifies the handling of the viscous material.

[0012] The present emptying apparatus and method can be used for handling several different viscous materials. Hereby, the viscosity of the material may be from 5 000 to 1 000 000 mPs. The apparatus has turned out to work particularly well in emptying a container that contains material with a viscosity of 50 000 to 300 000 mPs.

[0013] The present apparatus and method are also easy to use. In particular, if roller arrangements have previously been used in emptying flexible containers, no essential changes are required in either mounting the apparatus or in handling it.

[0014] Further advantages and details of the invention are disclosed in greater detail in the description below.

SUMMARY OF THE FIGURES

[0015] In the following, the invention will be described in more detail with reference to the appended drawing, in which

Figure 1 shows a vertical section of an apparatus known as such for extending a flexible container when the container is emptied;

Figure 2 shows a side view of a roller arrangement known as such to be used in emptying a flexible container, seen from the side;

Figure 3 shows an axonometric view of an emptying apparatus with the above roller arrangement according to the present invention when the emptying of a flexible container starts;

Figure 4 shows a sectional view of a roller arrangement in a position according to Figure 3;

Figure 5 shows an axonometric view of an emptying apparatus when the emptying of a flexible container has started;

Figure 6 shows a sectional view of a roller arrangement in a position according to Figure 5;

Figure 7 schematically shows functioning of the present roller arrangement;

Figure 8 shows an axonometric view of the primary parts of a roller arrangement according to the present invention;

Figure 9 shows a roller to be used in a roller arrangement according to, for example, Figure 8; and

Figure 10 shows a cross-section of the present roller along line B-B in Figure 9.

PREFERRED EMBODIMENT

[0016] The above-mentioned figures do not show the present emptying apparatus for emptying a flexible container in scale but serve only to illustrate structural solutions of the preferred embodiments and the functioning of the embodiments. Hence, the respective structural parts shown in the figures and denoted with reference numerals correspond to the structural solutions that are presented in the description below and are, at the same time, provided with reference numerals.

[0017] Figures 1 and 2 show known solutions used in emptying flexible containers today. Figure 1 shows a vertical section of an apparatus 1 for extending a flexible container 2 when the container is emptied. In the figure, one can distinguish an outer protective casing 3 and an inner transport bag 4 of the container. In order to empty the container, it is fastened by its upper side to a lifting hook 5 or the like tool, after which the container is extended in a vertical direction. In extending the container, it becomes laterally contracted, whereby the viscous material 6 in the transport bag is pressed out through a bottom opening positioned substantially farthest down, and further through a discharge pipe possibly arranged there as well.

[0018] Figure 2 shows how a flexible container 2, which is preferably extended in an apparatus according to Figure 1 , is provided with a roller arrangement 9 known as such. Such a roller arrangement affects the flexible container in such a way that the rollers 10 positioned opposite each other are moved with a special conveying device (not shown) against each other. At the same time as the rollers are pressed against the container in a horizontal direction, the roller arrangement exerts pressure in a vertical direction, either by means of the rollers' own weight or by means of active moving against the roller arrangement in a vertical direction oriented towards the bottom opening 7 comprised by the container or formed therein.

[0019] As can be seen in Figure 2, the rollers 10 form, however, a bubble 1 1 which is positioned above the rollers' closest surface oriented towards each other. Since the roller arrangement cannot completely tighten the passage 12 between the rollers, some of the viscous material 6 in the container always slips into this bubble, and thus it is prevented from being pressed out of the container.

[0020] In an emptying apparatus 20 according to Figures 3 and 5, substantially the same primary structural parts can be seen as in the known solutions described above. Thus, there is an extending arrangement 21 for extending the flexible container 22, and a roller arrangement 23 for exerting pressure on the opposite wall surfaces of the flexible container. The roller apparatus is preferably arranged to be moved in a substantially vertical direction along guides 24 in the extending arrangement. [0021] Unlike in the known solutions, the rollers 25 in the roller arrangement 23 are provided with recesses 26 according to Figure 4, for example. Thus, according to the present embodiment, rollers oriented towards each other assume a position in which a protrusion 27 of one roller, formed by the adjacent recesses, is arranged to be able to be inserted into the recess of the opposite roller. This is seen particularly well in Figure 7.

[0022] In these rollers 25 positioned opposite each other, the protrusion 27 together with the recess 26 are arranged to close the nip 28 formed between the adjacent parallel rollers at least partially. Since the rollers in this roller arrangement 23 are caused to rotate along the flexible container 22, it is preferable to form the rollers to have substantially equal diameters to achieve, in this way, as even reciprocal rotation as possible.

[0023] In its preferred embodiment, said roller 25 comprises a toothed roller according to Figures 9 and 19, where the teeth 29 form said recesses 26 and protrusions 27 of the opposite rollers. In experiments, it has turned out that preferable functioning for the present roller arrangement 23 is achieved when the toothed roller has an outer diameter d _k that is in the order of 130 mm. Hereby, the toothed roller is provided with teeth having a tooth height in the order of 10 to 30 mm, preferably 10 to 20 mm, most preferably 15 mm.

[0024] By means of this structure, a roller arrangement 23 is obtained where the tops of protrusions 27 in one roller almost reach the bottom of recesses 26 in the other roller, while the rest of the teeth are farther from each other in this position. The nip 28, which is thus formed between those surfaces of the adjacent rollers that are positioned closest to each other, hereby obtains a clearance of about 1.5 mm. The size of this nip is sufficient for conveying the protective casing of the container and the foils of the transport bag through the nip. At the same time, the nip is sufficiently small so that the protrusions formed by the tooth tops close the passage between the rollers and thus prevent the viscous material 30 in the container from escaping to the wrong side of the rollers. This function is illustrated particularly by Figure 7.

[0025] As can be seen particularly in Figures 7 and 10, the shape of the recesses/protrusions, i.e. the tooth profile of the roller, is preferably constructed such that it has a substantially triangular cross-section. A vertex angle 31 of this triangle is in the order of 50 to 70 degrees, preferably 55 to 65 degrees, most preferably 60 degrees. A structure that works particularly well is obtained by choosing a structure having a tooth profile with a cross-section of substantially the shape of an isosceles triangle. There is reason to note that in spite of the embodiment of the figures being provided with substantially triangular teeth, the embodiment is not restricted to this in any way. The teeth may as well be completely round, for instance of an involute type.

[0026] On the other hand, to prevent the viscous material 30 in the flexible container from escaping on the sides of the toothed surface of the roller, it is preferable to shape a roller according to Figure 9, so that it has a length in the order of 400 to 900 mm, preferably 450 to 750 mm, most preferably 500 to 600 mm.

[0027] To lock the opposite rollers 25 of the roller arrangement 23 against each other, the arrangement according to Figure 8 comprises a locking plate 32 made of steel, for example, at both ends of the rollers. The rollers being arranged in a position adjacent to each other, the locking plate is moved from its rest position according to Figure 4 to a lock position according to Figure 6 where gripping recesses 33 in the locking plate are, at the same time, arranged to surround the parallel shafts of the rollers, which prevents the rollers from being pressed away from each other during the emptying of the flexible container 22. The rollers are moved against each other for example by the effect of one or more hydraulic or pneumatic cylinders. The movement may also be implemented with one or more spindle motors or chain arrangements. A preferred embodiment shown in Figure 8 comprises rotation plates 34 fastened to both ends of the rollers. The rotation plates are arranged to be turned in relation to each other, whereby they press the rollers against each other. By turning the rotation plates somewhat over the dead point of the structure, the position of the rollers is locked mechanically relative to each other and a continuous pressure can be exerted on the flexible container without allowing the rollers to distance from each other.

[0028] The roller arrangement 23 comprises at least one motor (not shown) for driving the rotation of the rollers 25 and thus feeding the flexible container between the nip of the roller arrangement according to Figures 5 to 7. If a pneumatic motor is used, it is arranged for instance to give a torque of about 14 Nm at an air-feeding pressure of 7 bar. By arranging the motor to influence the roller 25 via a gear box preferably having transmission of 200 times, a torque of about 3 000 Nm is achieved for the shaft of the rollers. This also causes an internal pressure in that part of the flexible container 22 which is delimited by the bottom opening and the roller arrangement. This internal pressure presses the viscous material 30 out of the bag without a need for a pump in the emptying work.

[0029] The present emptying apparatus 20 works in the following way. The viscous material 30 is discharged from a flexible container 22 known as such through at least one bottom opening comprised by the container or formed therein by influencing the flexible container with a roller arrangement 23. At the first stage of the work, the container is extended so that the bottom opening becomes positioned substantially farthest down, after which at least two of the rollers 25 in the roller arrangement are brought against the outer surface of the container so that the flexible container becomes positioned between a nip 28 formed by the rollers. These rollers are subsequently moved towards each other and will also during the work process proceed onwards in a direction towards the bottom opening along an imaginary vertical axis of the container.

[0030] When the rollers 25 are moved against each other, the flexible container 22 is pressed against recesses 26 of one roller by protrusions 27 of the other roller positioned oppositely according to Figures 5 to 7. The rollers are pressed against each other with a force that forces primarily a cross-section of the flexible container to assume such a position in a recess in which the nip 28 is at its smallest. See for example Figure 7. By cooperation of the rollers and the outer protective casing and inner transport bag of the container, a block is formed at the nip between the rollers. This block substantially prevents flow of the viscous material 30 from the container part that has not yet reached the rollers to the container part that has passed the rollers.

[0031] Since a material flow through the nip 28 defined by the rollers 25 positioned opposite each other is prevented, an inner pressure is simultaneously generated in the material 30 in that part of the container which is between the bottom opening and the roller arrangement 23, whereby this pressure accelerates the emptying of the flexible container 22.

[0032] The pressure generated by the rollers in the flexible container 22 is dependent on material creases in the container, the viscosity of the viscous material 30 present in the container etc. This also allows the width of the nip 28 to be adjusted between the rollers 25 by stopping the movement of the rollers in relation to each other at somewhat different stopping points.

[0033] The rollers 25 are preferably pressed against each other so that the protrusion 27 of one roller assumes such a position in the recess 26 of the opposite roller in which the distance between the top of the protrusion and the bottom of the recess is in the order of 0.5 to 5 mm, preferably 1 to 3 mm, most preferably 1.5 mm.

[0034] At the same time as they are pressed against each other, the rollers 25 are rotated in opposite directions so as to be moved along the imaginary vertical axis of the flexible container towards the bottom opening and to generate a continuous pressure in the viscous material 30.

[0035] The present method for emptying a flexible container 22 is well applicable when the container contains a viscous material 30 with a viscosity in the order of 5 000 to 1 000 000 mPs, preferably 50 000 to 300 000 mPs.

[0036] The above description and the figures presented are only intended to illustrate the present solution for the structure of an emptying apparatus for emptying a flexible container, and utilization of a method for emptying this container. Therefore, the solution is not restricted only to the embodiment described above or in the attached claims but a plurality of variations or alternative embodiments are feasible within the idea described in the attached claims.