NO862873L - BULK TRANSPORT CONTAINER. - Google Patents

Description

The invention relates to transport containers for flowable materials, more specifically transport containers for bulk transport of flowable materials, including liquids, powder material or granular material, semi-solid materials, such as

fats, pastes or adhesives and also highly viscous fluids, in the volume corresponding to at least 200 liters and in quantities by weight over 200

kg.

Transport containers used for the transport of flowable bulk material must be able to withstand large weight stresses,

as a result of the material's high density and must at the same time be designed so that they can withstand damaging effects that may arise from

the uneven and sometimes cyclic stresses caused by the material shifting during handling and transport. Even a small puncture or crack can cause a complete loss of the flowable material. Large, heavy-duty transport containers such as those in question, which contain flowable bulk material, exceed the limits of manual handling and are therefore usually mounted on pallets for handling using mechanical equipment such as forklifts and hand-operated lift trucks.

Different types of containers and materials for containers intended for the transport of flowable bulk material are known. Corrugated cardboard containers have, for example, been used as cheap disposable containers for less demanding purposes. Such containers are, if necessary, coated with wax or provided with an inner plastic bag. However, as volume and weight increase, the material pressure against the container will cause the container sides to bulge out. This makes it difficult to stack such a container together with other similar containers. Furthermore, the bulging of the container sides will

greatly reduce the inherently limited buckling strength of the container wall, so that such containers are therefore unsuitable for stacking or other demanding applications.

Cardboard or cardboard are expressions that are used in connection with containers. This refers to a relatively wide range of materials that are usually made from wood pulp or paper pulp. A commonly used material is corrugated cardboard. Corrugated cardboard is made up of paper webs, for example a central corrugated web and two smooth side webs Corrugated cardboard will usually be stiffer than other types of cardboard and therefore allows the manufacture of larger containers, which will be more stable to be able to take a significant weight.

Corrugated cardboard of various types thus offers many significant advantages with regard to the packaging and transport of relatively heavy loads. A double-walled corrugated board shall here be understood to

be one where two wavy courses are inserted between three smooth courses. A triple-walled corrugated board is here to be understood as one where three corrugated webs are inserted between four smooth webs. Such a triple design is particularly advantageous and can be more advantageously compared to wood with regard to stiffness and strength as well as costs, while at the same time it provides a damping quality that cannot be found in containers made of wood. In addition, triple-corrugated cardboard, compared to other types of cardboard, will have an advantageous high breaking strength. The breaking strength of a triple-walled corrugated container allows the containers to be stacked with contents, without excessive bulging or collapsing of the vertical container walls. Triple-walled corrugated cardboard also has great tear strength.

Corrugated cardboard containers are known which are built up with a

outer polygonal tubular body and a similarly designed internal reinforcement, thereby strengthening the container. Here, for example, reference should be made to US-PS 3,159,326, 3,261,533, 3,873,017, 3,937,392, 4,013,168 and 4,418,861.

In order to be able to shape polygonal corrugated cardboard tubes, it is necessary to create main folding lines in the corrugated cardboard so that it can be bent along the edges of each of the wall sections that the container will have. Such scoring, however, has a negative influence on the container, because the lateral stability of the container is significantly reduced in step with the increase of such lines. These main folding lines will usually allow the container in an empty state to be folded up and thus can be transported in such a flat, folded state.

The circular-cylindrical shape has long been considered to be the most efficient shape for containers that must contain liquids or, in a dry state, flowable products. Cardboard containers with such a circular cylindrical shape have, however, been limited to relatively small cylindrical containers, usually with a capacity of 200 liters and have been built up with spiral winding. The manufacture of larger containers of this type has proved impractical on a commercial basis. There are several reasons for this, including large material consumption and high production costs, as well as the fact that there is no satisfactory production equipment. Moreover, such drum-shaped containers are rigid and cannot be folded flat when empty. Existing technology requires these containers to be manufactured at a central location with subsequent dispatch and storage in an empty state at the point of use. Such containers therefore present problems with regard to handling, transport and storage. More significantly, the constructive structure and the handling requirements placed on such a container, when the capacity increases to the range of 400 - 1450 litres, have been shown to exceed the industry's ability to produce a readily available commercial product. The use of reinforced plastic or metal containers has not proven to be a satisfactory alternative, because such materials are usually more expensive, do not provide increased utilization of the storage space when empty, and otherwise present waste problems.

Despite the fact that circular-cylindrical containers have certain advantages, corrugated cardboard has thus far not been used as a material for such circular-cylindrical containers. Corrugated cardboard, especially of the stronger type, intended for weights and hydrostatic pressures found in the volume range 400 - 1450 litres, is not immediately suitable for production in circular cylindrical shapes without significant loss of important properties that precisely the corrugated cardboard has, that is say top-bottom compressive strength and lateral stability.

The invention relates to a transport container for bulk material, including an inner tube sleeve made of multi-walled corrugated cardboard and with a mainly circular cross-section, designed to be able to accommodate a flowable bulk material, and an outer sleeve with a polygonal cross-section, placed around the inner sleeve over its entire length, while also the outer body is made of multi-wall corrugated cardboard. The inner wall of the inner sleeve is provided with several false scorings which extend in the longitudinal direction, that is to say essentially parallel to the length of the inner sleeve or parallel to the waves in the corrugated cardboard.

The outer sleeve is preferably made of triple-walled corrugated cardboard and preferably has an octagonal cross-section.

The inner sleeve is a corrugated sleeve in the form of a right circular cylinder, made from a multi-walled corrugated board, for example a double-walled or preferably a triple-walled corrugated board, which has been subjected to a bending process to thereby provide the aforementioned false scoring in a random distribution in intervals of between 2.5 and 15 cm.

Preferably, the outer sleeve of the container is provided with bottom end flaps of single-walled corrugated cardboard, and is also provided with a removable upper end cover formed of bitten corrugated cardboard. Such transport containers can take flowable materials

in volumes of at least 200 liters and with a weight exceeding 200 kg.

The transport container according to the invention will, compared to the previously known drum-shaped containers of steel or fiber material, have a much lower volume unit cost both with regard to materials and production. Transport containers according to the invention provide increased utilization of available storage space during storage or transport in an empty state, because the new transport containers can be folded flat when not in use. In addition, the materials used will be of the recyclable type and the materials are also biodegradable, so that throwing them away after use does not present the waste problems that are known in connection with plastic and metal containers.

The invention shall be explained in more detail with reference to the drawings, where: Fig.l shows a schematic broken perspective view of a transport container according to the invention,

Fig. 2 shows a top view of a transport container, with reduced

lid and designed in accordance with the 'invention,

fig.3 shows an enlarged section of the one marked in fig.2

detail,

fig.4 shows a section of part of a side and the bottom i

the transport container in fig.l,

fig.5 shows a ground plan of a blank, before the placement of false scoring, for shaping an inner sleeve in

the transport container,

fig.6 shows a plan of a blank for shaping a

outer sleeve in the transport container,

fig.7 shows a section along the line 7-7 in fig.6,

fig.8 shows a perspective section of the outer sleeve with

end flap, and

fig.9 shows an exploded view in perspective, where the individual

components of a transport unit are shown.

The transport container 10 is constructed with a straight circular cylindrical inner sleeve 12 of multi-walled corrugated cardboard, this inner sleeve being coaxially engaged inside an outer sleeve 14 which also

is made of a multi-walled corrugated board. However, the outer sleeve has

polygonal cross-section, as can best be seen from fig. 1, 2 and 3. The inner sleeve 12 can be of single-walled or double-walled corrugated cardboard. In accordance with a preferred embodiment, however, here the inner sleeve 12 is built up of a triple-walled corrugated cardboard, see fig.3. Corrugated cardboard and especially the stronger types, such as double-walled and triple-walled versions, when used for the inner sleeve, will significantly increase the stacking strength of the container, compared to inner sleeves made of solid cardboard or single-walled corrugated cardboard.

The inner sleeve 12 is designed from a basically flat corrugated cardboard web. This flat track 11, see fig.5, is first provided with two main scoring lines 13,17, preferably arranged diametrically opposite each other in the finished sleeve. In this way, the empty inner sleeve can be folded together and transported flat. The web 11 is given a circular shape in a bending device, for example a sheet metal roller or a modified cutting device with four bars. The web is subjected to a crime which consists in the corrugated cardboard web being made to pass through a curved section with a radius of curvature which results in the formation of randomly distributed scores 75, here called false scores. These go in the same direction as the waves in the corrugated cardboard,

on the inside of the curved corrugated board.

The randomly spaced fake scores 75, which in the case of a triple-walled corrugated board, will have mutual distances varying between 2.5 and 15 cm, help to facilitate the shaping of the inner sleeve 12 as an almost perfect circular-cylindrical hollow body when the inner sleeve is placed inside in the outer polygonal sleeve and is filled with liquid or a flowable solid material. In addition to these random scoring, the breach will also cause a stretching of the outer side of the corrugated board and a compression of the inner side to such an extent that the sleeve, when glued to its sleeve shape, will have a circular-cylindrical shape when raised from the collapsed state . The end parts of the corrugated board overlap each other and are glued together in an overlap joint in the sleeve. The outer surface of the inner sleeve

will not fold or score but will remain smooth.

The random false scores 75 will, when the corrugated cardboard is formed into a sleeve, extend mainly along the longitudinal axis of the inner sleeve 12. The term "false scoring" as used here is intended to include the type of scoring or fold lines that appear when a track material is subjected to a damaging stress, and it does not therefore refer to scoring or fold lines of the type produced by means of a tool . As best shown in fig.3, these false scoring will only give impressions in the innermost side path in the sleeve 12. Compared to this, it can be seen that the mechanical scoring or folding lines 13,17, which are designed to allow a regular folding of the blank, also extend into the inner wave layer. It is essential that one utilizes the described false scoring to achieve the circular cylinder shape, because a greater number of mechanical folding lines will have a negative influence on the sleeve's strength properties.

The outer sleeve 14 includes, in accordance with a preferred embodiment, a tubular body which has an octagonal cross-section. The outer sleeve 14 is formed from a mainly rectangular web blank 16 of corrugated cardboard, or similar, see fig.6. The blank 16 is punched out and provided with folding lines in a manner known per se. The subject has several essentially rectangular wall panels 18, 20, 22, 24, 26, 28, 30 and 32 which are connected to each other by means of folding lines or scoring 34, 36, 38, 40, 42, 44, 46. Furthermore, a sealing flange 48 is foldably connected to the wall panel 32 by means of a folding line 50. End flaps 52,54,56, 58,60,62,64,66 are designed on one end of the respective wall panels and can be fastened around the folding lines 51,53,55,57,59,61, 63,65 formed in each end flap approximately 3 mm from the bottom edge 68. The wall panels are preferably made of triple-corrugated cardboard, i.e. corrugated cardboard which has three corrugated paths 70,72,74, as is shown in fig.7. The corrugated tops are glued to the smooth webs 76,78,80 and 82. The end flaps are preferably formed from single-wall corrugated cardboard, as shown in fig.8, formed in one with the triple-corrugated cardboard. The end flaps can be formed in a triple-wall forming machine during the shaping of the corrugated cardboard, in a manner known per se.

The blank 16 is bent along the fold lines so that an octagonal tube is produced. The flange 48 overlaps the side track 76 and is glued to this, to form an outer sleeve 14. The end flaps are folded inward into the sleeve, so that they partially overlap each other. The use of end flaps increases the strength of the container. The end flaps can be omitted and you can then optionally use a lower cover similar to the upper cover, but the overall result will not be quite as good. Alternatively, end flaps can be used in combination with an end cover.

The inner sleeve 12 is then inserted into the outer sleeve 14. The outer sleeve 14

is dimensioned so that the wall of the inner sleeve will rest against the walls of the outer sleeve approximately in the middle of these, as shown with the reference number 15. Between the inner sleeve 12 and the corners of the outer sleeve 14, a gap 19 will form. The corners of the outer sleeve are formed with the help of the said fold lines between the wall panels in the outer sleeve 14.

Although the outer sleeve 14 here has an octagonal cross-section, any polygonal cross-sectional shape can of course be used.

The container 10 is preferably closed at the top by means of a removable end cover 90. This has a plan that corresponds to the shape of the outer sleeve and thus has here an octagonal shape. The end cover 90 has a downwards circumferential flange 92 which will extend down along and abut against the outer sleeve a distance below the upper edge of the outer sleeve. The end cover 90 is not a load-bearing element and can therefore be formed from single-walled corrugated cardboard.

Fig.9 shows a shipping unit according to the invention. A pallet 96 of a conventional type is used under the transport container to thereby facilitate a transfer of the container by means of a forklift or a lift truck. In the outer sleeve, a base 98 is preferably inserted which rests on the folded-in end flaps 52,54,56,58,60,62,64. The bottom 98 here has an octagonal shape and is tightly fitted into the outer sleeve. The peripheral edge thus rests against the wall panels in the outer sleeve. The base 98 is preferably formed of triple corrugated cardboard.

A plastic bag 100 is arranged inside the inner sleeve 12, so that the container is sealed. This bag or lining 100 prevents the material from flowing out into the possible spaces between the end flaps and the bottom. A suitable bag 100 can be one made from a flexible plastic film material, for example extruded polyethylene film or the like.

In certain cases, a compressible top 102 is used. This has a circular cross-section and serves as a filler, i.e. as an element that takes up the space that may be available on the top, for example as a result of insufficient filling, collapse or contraction of the goods in the container. This top 102 is particularly suitable when the content is a liquid because such a top will prevent unwanted sloshing of the liquid when the container is moved during transport. As the top 102 is compressible, it will still allow a certain liquid expansion with associated relief of some of the hydrostatic or hydraulic pressure that would otherwise act against the side walls and bottom of the container. The top 102 is preferably made of corrugated cardboard or polyether foam. The circumference of the top rests against the inside of the inner sleeve 12. Steel band 84 is used to hold the transport container on the fall 96. To avoid damage to the end cover 90, inverted U-shaped steel band hoops 86 are mounted on top of the cover 90. These band hoops will lie between the upper side of the cover and the bands 84. Each such hoop 86 consists of a central flat part with downward-extending legs which rest against the cover's top and flanges 92, respectively. The hoops 86 have a greater width than the bands 84, in order to achieve a more even distribution of forces. The hoop surface is preferably provided with small knobs or warts to prevent slipping between hoop and band. When the hoops 86 are tightened down with the help of the bands 84, the inner sleeve 12 will be pressed against the bottom 98, whereby a further stabilization of the load is achieved. The end flaps are held in place under the influence of the filled material,

which presses down towards the bottom, and this load, together with the pressure of the hand, will provide a reinforcement which causes a resistance to lateral deflection in the bottom of the outer sleeve 14, that is to say the area which is most susceptible to buckling or deflection.

The bag may optionally have a spout 88 at the bottom. This spout 88 exits through cut-out portions in the outer sleeve and the inner sleeve. The spout 88 enables emptying of the material from the bag 100 without turning the container over. As shown, the spout goes through openings in the wall of the inner sleeve and the outer sleeve.

Containers constructed in accordance with the present invention have been subjected to drop tests, vibration tests and compression tests, under conditions of high humidity, and the results have been very good. Below are some examples.

Example 1

A transport container was made in accordance with the invention. The outer sleeve was made from triple-walled 1500 AAA corrugated cardboard. The outer sleeve had an octagonal cross-section with a width of

about. 100 cm and a height of approx. 112 cm. The inner sleeve was too

of triple corrugated board type 1500 (Beach puncture test rating) AAA. This corrugated cardboard was bent into a circular-cylindrical shape, forming random scoring. Bottom end flaps of the single-wall type were used. An octagonal bottom of 0900AAA corrugated cardboard and an upper cover of 725 single wall corrugated cardboard were used to close the ends of the outer sleeve. A plastic bag, filled with 833 liters of water, was placed in the container. A top made of triple wall 0900AAA corrugated cardboard and of octagonal shape was placed on top of the bag to fill the space between the bag and the top cover. Three steel bands were used to fasten the container to a wooden pallet which had

dimensions 112 x 112 cm. The steel bands had a width of 19 mm and a thickness of 0.5 mm. Two bands were placed in the same direction, while one band was placed at a cross with these. Each band was placed over a hoop made of a 12.5 cm wide 16 gauge sheet metal material, with 7.5 cm long deflected legs. The plate material was roughened to achieve the aforementioned anti-slip protection.

The container was tested using a distribution cycle according to ASTM standard D-4169, distribution cycle No. 11 rail, trailer on flat car, thereby simulating handling, vertical linear motions, loose-load-rotation-vibration and panning. The liquid remained in the bag throughout the test, with no leaks.

(A) Handling drop test

During the drop test, the container was lifted 15 cm from a concrete floor using a fork lift and dropped onto the edge. The test was repeated on the opposite edge. No leaks were detected.

(B) Vertical linear movement, vibration test

The container was subjected to vibration by being placed

on a vibrating table with a drilling projection of 2.5 cm. Low and medium vibrations here simulate transport conditions during truck transport and contribute to being able to determine whether the container is subjected to a destructive resonance. The container was held horizontally. The container was placed on the table and subjected to 260 cycles per minute over a period of 40 min. The container was then placed on a table with stronger vibration. Again, the container was held in the horizontal direction and subjected to vertical vibration for 40 minutes, with the following frequencies and results:

No leaks were detected.

( C) Loose load rotational motion vibration test

The container was also placed on a rotary-vibration table

with a projection of 2.5 cm. This experiment serves to simulate a side-to-side movement, as it often occurs in rail transport or semi-trailer transport. The container was vibrated for 20 minutes at a frequency of 235 rpm. It was then turned 90° and vibrated for another 20 min. with a frequency of 235 rpm. No leaks were detected.

( D) Brushing/oblique impact test

The container was placed in an inclined impact machine for impact against

a wall to thereby simulate impact stresses during rail transport. A second container (also filled) was placed behind the first container. The container was subjected to a 4 mph impact two 6 mph impacts. No leaks were detected.

Example II

A transport container made according to the invention (equivalent

as in example I) was first exposed to a high humidity climate. A plastic bag was filled with 833 liters of water and placed in the container. The container was conditioned at 32°C and a relative humidity of 90%. After 72 hours, the conditioned container was subjected to compression tests to simulate the conditions during stacking.

A load was applied to a top plate which moved downwards with

a speed of 12.5 mm per my. until the container failed. The container failed only after a load was reached

of 3870 kg.

Example III

A container made as in Example I was conditioned for 72 hours

at 22°C and a relative humidity of 50%. A plastic kit was filled with 833 liters of water and placed in the container. A load was applied as mentioned under example 2. The container failed only when a load of 8100 kg was reached.

It is a special feature of the new container that the inner sleeve

12 can be filled with a flowable bulk material without

bulge out. This is due to the circular cross-section in the inner sleeve 12, which causes a pressure transfer from the flowable load in the form of exclusively circumferential stresses in the sleeve wall,

with associated resistance to bulging of the walls.

As a result of its construction of double-walled or triple-walled corrugated cardboard, the outer sleeve 14 will be well suited to withstand end loads, so that several such containers can therefore be stacked on top of each other.

The container's increased ability to absorb and withstand static and cyclic loads is due to a structure using the circular inner sleeve and polygonal outer sleeve against which the inner sleeve rests. Designs where solid cardboard walls or walls are used

of single-wall corrugated cardboard (2 smooth side panels) in the inner sleeve and outer sleeve, is not suitable for transport containers of the type in question here and is therefore outside the scope of the invention.

The transport container according to the invention is therefore primarily intended for receiving flowable bulk materials in volumes of at least 200 liters and with a weight of 200 kilograms and more.

A transport container as described above, and used together with a plastic bag, is suitable for liquids and dry flowable products in volumes of between 200 liters and up to 1450 litres. Liquids and suspensions with a specific gravity of up to 1.5 kg/litre and flowable dry solids with a specific gravity of up to 1.8 kg/dm 3 can be easily filled and transported in containers according to the invention, in the aforementioned volume range.

Claims (12)

1. Transport container (10) for flowable bulk material and of the type which includes an outer sleeve (14) with an octagonal cross-section, an inner sleeve (12) which has a mainly circular cross-section and is mainly coaxially mounted inside the outer sleeve (14), which outer sleeve has several parallel wall sections (18,20,22,24,26,28,30,32), while the inner sleeve (12) has an axially continuous central contact against each of these wall sections, characterized in that the inner sleeve (12) has an internal limitation with several false scorings (75) which extend axially along the inner sleeve (12), and in that the inner sleeve (12) and the outer sleeve (14) are both made of triple-walled corrugated cardboard. 2. Transport container according to claim 1, characterized in that the inner sleeve (12) is built up of a triple-walled corrugated cardboard web which is led through a curved section to thereby give a curvature to the web and provide randomly spaced false scores in the inner wall of the inner sleeve, in the same direction like the waves, as the path edges are brought to overlap and glued together. 3. Transport container according to claim 1 or 2, characterized in that the false scoring in the inner sleeve has a distance of from 2.5 - 15 cm. 4. Transport container according to one of the preceding claims, characterized by several end flaps (52,54, 56,58,60,62,64,66) each of which is foldablely connected to a respective one of the mentioned wall fields at a first end of the outer sleeve (14), as each such end flap is made of single-walled corrugated cardboard and each end flap is folded inward into the outer sleeve 14. 5. Transport container according to claim 4, characterized by a wooden bottom (98) with an octagonal cross-section and placed on the end flaps, between these and the inner sleeve (12). 6. Transport container according to claim 5, characterized in that the bottom (98) has a peripheral edge that rests against the wall panels in the outer sleeve (14). 7. Transport container according to claim 5 or 6, characterized in that the bottom (98) is made of triple-walled corrugated cardboard. 8. Transport container according to claim 7, characterized by the wood sack (100) for flowable material, placed inside and essentially completing the inner sleeve (12). 9. Transport container according to claim 8, characterized in that it includes a top (102) and an end cover (90) for closing the other end of the outer sleeve (14), which top has a circular cross-section and is mounted inside the outer sleeve (12), between the bag ( 100) and the end cover (90) and has a circular circumference in contact with the inner sleeve. 10. Transport container according to claim 9, characterized in that the top (102) includes triple-walled corrugated cardboard. 11. Transport container according to claim 9, characterized in that the top (102) includes a compressible polyether foam. 12. Transport container according to claim 9, characterized in that the end cover (96) has a cross-section similar to the cross-section of the outer sleeve (14) and has side flanges running along the circumference that overlap the side wall of the outer sleeve, and that the container further includes several inverted U-shaped hoops (86) which is mounted on the end cover (90), each such hoop (86) having a central part which lies above the end cover between the flanges on the end cover, as well as downward-extending legs which extend down along opposite flanges on the end cover, a pallet (96) and strapping means ( 84) intended to lie above the aforementioned hoops, thereby holding the container on the pallet.