GB2156770A

GB2156770A - Containers

Info

Publication number: GB2156770A
Application number: GB08507197A
Authority: GB
Inventors: Barry Gordon Green; Andrew Peter Harrison
Original assignee: Lancaster Russam & Co Lim
Current assignee: Lancaster Russam & Co Lim
Priority date: 1984-03-20
Filing date: 1985-03-20
Publication date: 1985-10-16
Also published as: GB2156770B; GB8507197D0

Abstract

A container for flowable material such as liquids or powdered material comprises an outer shell and an inner shell, the outer shell being of rigid or semi-rigid construction and having a generally prismatic shape 10 and the inner shell being flexible or rigid and receiving the material to be contained. The outer shell is formed as a tube open at the top and bottom ends and has a closure element such as a bottom or lid 18 or support element for a detachable lid (Fig. 5) secured to one of the open ends by a rolled seam joint. The top of each side wall is rolled to produce a double thickness seam 20 parallel to but jogged inwardly of the main wall portion and an upwardly standing flange 22 defining a narrow socket between it and the seam 20 into which a lip of the lid fits, the projecting part of flange 22 being turned over onto the top of the lid. An optional outlet pipe may be provided (36, Figs. 6-8) and the lid may include a central opening for a screw threaded ring shaped adapter for receiving a threaded cap (Fig. 2). The inner shell may be of cross laminated high and low density polyethylene film, a rigid planar sustaining element being secured to at least one side to prevent creasing (Fig. 6). The outer shell may comprise two L-shaped members welded together at diagonally opposite corners. The inner shell may be attached to the outer shell in the region of the opening in the lid. <IMAGE>

Description

SPECIFICATION Containers The present invention relates to containers for the storage and transportation of flowable material, and more particularly, to containers which can be readily accommodated in a shipping container or on a pallet or stacking flat.

A known type of liquid container designed to facilitate transportation comprises an outer shell which is of a generally rectangular prismatic shape, and an inner shell in which the liquid is received, the inner shell being secured to the outer shell and having a generally cylindrical shape. The cylindrical shape of the inner shell is particularly well adapted for the transportation of liquid, partly because of its strength and partly because there are no corners in which small residual amounts of liquid can lodge. The rectangular shape of the outer shell facilitates stacking of the containers on pal lets or platforms and on top of similar containers, and at the same time, the outer shell physically protects the inner shell.

However, this known type of liquid container is relatively expensive, and the cost factor is especially important where, as frequently happens, transportation costs rule out return of the empty container for re-filling, so that it has to be scrapped after a single use.

Although such containers are generally used for the transportation of liquids, they can also be used for the transportation of semi-liquids, and solids which are in the form of powdered or grannular materials, so that they act as liquids in the sense that they are flowable, and also gases, particularly gases having a specific gravity greater than unity. The physical characteristic which distinguishes those products which the container is adapted to carry is the ability to flow.

It is the principal object of the invention to provide a low cost container for flowable material of the double shell type.

According to this invention a container for transporting and/or storing flowable material comprises an outer shell of rigid or semi-rigid construction which has a generally prismatic shape, and an inner shell to receive the material to be contained, the outer shell being made as a tube open at the top and bottom ends and having a closure element secured to one of the open ends by a rolled seam joint.

The closure element may comprise a lid or a bottom which itself substantially closes that end of the tube. Preferably part of each wall of the tube projects beyond the rolled seam joint and is turned over on to the outside of the closure element to secure that element to the tube.

In another construction, the closure element comprises a support, permanently attached to the tube by the rolled seam joint, to which a lid can be releaseably secured. In that case, the support may comprise a frame which fits into the open top end of the tube, and provided with a series of screw-threaded parts, the lid having a turned down rim which fits outside the walls of the tube when the lid is in position, and a series of screws passing through holes in the lid and engaging respectively in the screw-threaded parts of the support to releaseably secure the lid to the support.

The construction according to the invention allows the outer shell to be made of thin sheet material, for example mild steel of 20 S.W.G.

A tube of say 1 metre square cross-section and 1 metre in depth would not in itself have sufficient rigidity to protect the inner shell.

Even when the lid and bottom are added, the additional rigidity provided by the lid and bottom would not be adequate, especially if the lid is detachable. By using rolled seam joints around the ends of the tube (i.e. at the top and bottom) much greater rigidity is obtained in addition to securing the closure element (lid,bottom or lid support). It has also been found however, that the rolled seam joint gives another advantage in that it permits a configuration of the outer shell which readily admits of stacking the containers one on top of another, whilst avoiding the formation of sharp edges which could damage other containers.

The term "rolled seam joint" is used to describe a joint in which a marginal portion of the sheet material forming one element is bent to provide a socket in which a marginal portion of another sheet element can be received, and at least a double thickness of the sheet material alongside the socket, and in which the joint is secured by closing part of one element over the other element to hold the marginal portion of the other element in the socket.

Preferably the container has a lid and inlet holes are formed in the lid and the top of the inner shell and the marginal portions of both the lid and the inner shell around these inlet openings are nipped together, whereby the inner shell is attached to the outer shell.

It is further preferred that the inner shell is made of flexible material. The flexibility of the inner shell construction is preferably such that it will at least partially collapse when empty, but it is capable of expansion to a maximum internal volume when filled with a flowable material, and therefore the term "expansion" is used to describe the opening of the inner shell to its maximum volume, and is not intended to include actual inflation. On the other hand, it is preferred that the inner shell is strong enough not to suffer substantial stretching due to stress applied by the internal load when it is full.By manufacturing the inner shell in flexible material, very considerable manufacturing cost savings can be ef fected, whereby the container can be used in situations where the cost of a double shell container of the known (rigid inner shell) type container presently used for carrying liquids would be prohibitive.

It is preferred to make the inner shell in plastics film of thin sheet material having the required degree of strength and flexibility. A suitable material is polyethylene and a particularly effective material is made of cross-laminated high and low density polyethylene films. Compound films, such as co-extruded films, having two or more layers of materials with differing physical properties may also be employed.

According to a preferred feature of the invention, the inner shell has a rigid or semirigid planar sustaining element, secured to one of its sides to resist creasing of that side.

It is desirable to prevent creasing to avoid trapping material in the creases. This applies particularly of course, to the bottom of the shell, when materials such as semi-liquids or powders would be prone to lodge in any available creases, even when the container is being emptied.

In a preferred arrangement, the planar sustaining element comprises a sheet of card such as cardboard, boxboard, millboard strawboard and the like secured to the side of the inner shell by adhesive. The sustaining element could equally comprise a sheet of rigid plastics material, plywood or hardboard, but the use of card is preferred because it is relatively cheap.

The element can be attached to the shell over its entire surface, which is useful in resisting creases. However, it might be possible to secure the sustaining element to the inner shell only around the edges of the element, for example, by using adhesive tape.

Providing that side of the shell is stretched when the element is attached to it, the arrangement should be adequate to prevent substantial creasing.

It is further preferred that the outer shell is of generally rectangular prismatic shape. This retains the facility for stacking which is a feature of the known double shell type container. The outer shell may have secondary formations to give it additional strength, e.g.

dishing or ribbing, and it has been found that diagonal or chamfered corners are an effective way of increasing the rigidity of the outer shell.

In one construction, the marginal portions of the lid and the inner shell are nipped between a flange on an inlet adapter and a collar, so that the attachment of the inner shell to the outer shell is provided by the adapter and collar combination.

According to another preferred feature of the invention, the walls of the outer shell comprise two L-shaped members (as seen in plan) joined together, so that each arm of each "L" forms a side wall of the shell and the joints are at diagonally opposite corners.

An outlet opening is preferably formed in one wall of the outer shell near to the bottom of the container, for an outlet pipe and/or tap, and it is preferred to provide a substantially imperforate rigid barrier on the inside of this opening to protect the inner shell against damage by anything inserted through the outlet opening. Alternatively, the outlet may be formed in the bottom wall of the inner shell to permit removal of the contents of the inner shell through the bottom of the container. In some instances, the outlet may be omitted altogether, in which case, the container is emptied by sucking the contents out through the inlet.

A container, and a modification, both in accordance with the invention, will now be described by way of examples only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of the container mounted on a pallet, Figure 2 is a sectional detail view of a lid and inlet construction, Figure 3 is a detail section through a rolled seam joint in the course of production, Figure 4 is a view similar to Figure 3, but showing a later stage in production of the rolled seam joint, Figure 5 is a cross-section through a rolled seam joint used for adetachable lid, Figure 6 is a diagrammatic side view of an inner shell, shown removed from the outer shell, Figure 7 is a detailed view showing the attachment of an outer pipe to the inner shell, and Figure 8 is a perspective view inside the outer shell looking towards an outlet opening.

The particular container which is described hereafter is intended for the transport of liquids, and more particularly, for the transport of liquids on platforms or in containers, such as the I.S.O. containers used for international transportation purposes. Although a container in accordance with the invention could be used for the storage and/or transport of virtually any kind of liquid, it is thought that the most likely use is for transportation of non-dangerous liquids, since dangerous liquids may require containers of somewhat more substantial construction. On the other hand, a container in accordance with the present invention can be used to transport liquids of relatively high specific gravity, for example up to 1.4. Indeed, the container can also be used for transporting semi-liquids, grannular materials and powdered materials which will have even higher specific gravities.

Essentially, the container is a double-shell construction, and to that extent it resembles a known type of container used for the transpor tation of nondangerous liquids, which has rigid inner and outer shells. The outer shell 10 is made in sheet steel, and because the primary object of the construction is to provide a container which is relatively cheap, the sheet steel outer shell should be made quite thin, so long as it has sufficient rigidity to hold its shape, when the inner shell is filled with the liquid, powder or grannules to be transported. In a particular example, where the outer shell 10 is approximately a 1 metre cube, the sheet steel plate used for the outer shell may be of 20 S.W.G.

The walls of the outer shell 10 are constituted by two nearly identical parts 1 2 and 14, each of which when seen in plan comprises an L-shaped member, each arm of the "L" forming one side wall of the outer shell 10. At each of the corners, there is a diagonal or angled formation 16, which in the case of a 1 metre cube container may for instance be 80 millimetres in length. This angling of the corners adds considerably to the rigidity of each of the "arms" and also to the rigidity of the finished shell 10.

The two parts 1 2 and 14 are brought together, so that their edges can be joined by means of welds 1 9. As a resultof joining the two parts 1 2 and 14 together there is formed a generally rectangular prismatic tube, which is open at the top and bottom. A bottom (not visible in the drawings) is fitted into the bottom ends of the walls and secured to to those walls by rolled seam joints, the bottom providing a floor filling the entire cross-sectional shape of the outer shell. Similarly, a lid 1 8 is fitted to the top end of the walls of the outer shell, and secured thereto by rolled seam joints.

The formation of the rolled seam joint for the lid 18 is shown in Figures 3 and 4, and it will be understood that the rolled seam joint for the bottom is formed in the same manner.

The top marginal portion of each side wall of the outer shell is rolled to produce a double thickness seam 20 parallel with, but joggled inwardly of the main portion of the wall, and an upstanding flange 22 parallel with the seam 20, but with a narrow socket 24 between the seam 20 and the flange 22. As shown in Figure 3, part of the flange 22 projects above the top end of the seam 20.

The lid 1 8 has a downwardly depending lip 26 which can be pressed into the socket 24 (see Figure 4). The lip 26 may be a tight fit in the socket 24 so that it is retained therein, or the joint may be rolled after the lip is inserted to close the socket and cause the lip to be gripped tightly. In any case, after the lid has been fitted, the projecting part of the flange 22 is turned over as indicated by the dottled line in Figure 4 to close on to the top of the lid.

The rolled seam joint not only holds the lid securely on the tube of the outer shell 10, it also reinforces the walls of the outer shell.

Moreover, it ensures that there are no sharp edges on the joint of the lid and the tube.

The construction shown in Figures 3 and 4 provides a permanently attached lid. Sometimes, a detachable lid may be required, and for this purpose, the rolled seam joint shown in Figure 5 is employed. Initially the walls of the outer shell are formed with the seam 20 and flange 22 as shown in Figure 3. A rectangular support frame is provided comprising four support elemenets 30 each of which is made of sheet material bent into an 'L' shaped cross-section, one arm of the "L" forming a lip to fit in the socket 24 of the joint. The support frame fits inside the top end of the tube of the outer shell as shown in Figure 5, but of course it only covers the outer marginal portion of the open top and of the tube. The projecting part of the flange 22 is bent over on to the top arm of each support element.

At spaced locations around the support frame, holes are formed through the frame and a nut 32 is welded to the underside of the frame in alignment with each hole. The lid 1 8a is somewhat larger than the lid 18, so that its lip 26a fits over the outside of the flange 22. A series of holes is formed through the lid at positions aligned with the holes in the support frame, and cup-headed screws 34 are used to secure the lid to the support frame. The lid can be detached by first removing these screws.

It will be appreciated that once the floor and lid are fitted into the walls of the outer shell, that shell assumes a greater rigidity than is provided by the walls themselves. For all practical purposes, the outer shell can be regarded as a rigid rectangular prism, although in fact, because of the very thin walls, it may be capable of sustaining slight bending. Some or all of the walls may be slightly dished or formed with ribs, as a means of provided greater rigidity if required.

The inner shell 20 (see Figures 2, 6 and 7) is a large plastics bag, with very flexible walls.

In this particular construction, the inner shell is made from cross-laminated high and low density polyethylene films. Such film is marketed for example by Van Leer Flexibles of Poole under the Trade Mark VALERON.

Essentially, cross-laminated film is formed from a plurality of film sheets in some or all of which, the molecular structure has been orientated, but the sheets which are joined together to form a laminate have their molecules orientated in different directions (for example at 90" to each other). The plurality of sheets are brought together during manufacture, so as to produce what is in effect a single sheet or film of very considerable strength.In the particular construction which is being described, the inner shell 40 is made from a multiple laminate material comprising: -a layer of low density polyethylene 1 25 microns thick; -a layer of low density polyethylene 5 to 10 microns thick; -a layer of high density polyethylene 37.5 microns thick; -a layer of low density polyethylene 5 to 10 microns thick; -a layer of high density polyethylene 37.5 microns thick.

At least the two high density polyethylene layers have their molecules orientated in directions which are inclined with respect to the direction of orientation of the molecules in the other of these two layers. In any case, in order to handle materials having specific gravity up to 1.4, the inner shell 40 should be made of polyethylene film between 1 50 and 250 microns thickness. On the one hand, the thickness of the film will be determined by the strength required to hold the considerable quantity of material which can be accommodated in the inner shell, but on the other hand, the material used for the construction of the inner shell should be as thin as possible in order to minimise the expense of manufacture.

The inner shell 40 has heat sealed seams, and when expanded (that is opened out to its maximum size) it is generally a rectangular prism, capable of nearly filling the outer shell 10. The material which is to be contained has to be held in the inner shell 40, and it is generally desirable to avoid creasing of the inner shell 40, when the latter is expanded, because of the possibility of material lodging in the creases. This of course is particularly true of the bottom side of the inner shell. As illustrated in Figure 6, top and bottom planar sustaining elements 50 and 52 are secured to the top and bottom sides of the inner shell 50. Each of these sustaining elements 50 and 52 is made in card, which whilst it assists in preventing creasing of the side to which it is secured, is nevertheless relatively cheap.It will be noted, that the top sustaining element 50 extends over substantially the entire top surface of the expanded flexible inner shell, whereas the bottom sustainer 52 terminates some distance from the lefthand side of the container as seen in Figure 6. The sustaining elements 50 and 52 are preferably attached to the inner shell 40 by adhesive. This can readily be achieved, by coating the underside of the top sustaining element 50 and the top side of the bottom sustaining element 52 with adhesive, and then expanding the inner shell 40 by blowing air into it, until its top and bottom sides engage with their respective sustaining elements under the internal pressure provided by the air which has been blown into the shell. This is sufficient to produce the necessary adhesion of the sustaining element to the shell.It should emphasized, that whilst the sustaining elements 50 and 52 prevent creasing of the inner shell 40, they do not give that shell a general rigidity, and it is still capable of collapsing upon itself.

It has been found possible in some instances to dispense with the top element 50 and to rely on the bottom element 52.

A moulded plastics inlet adapter 64 is provided which is illustrated in Figure 2. It should first be noted that an inlet opening 60 is formed in the centre of the lid 18, but part of the lid around the opening 60 is dished inwardly as shown at 62. The adapter 64 is a ring which lies on the dished part of the lid, and a lip 66 which projects through the hole 60. Internally, the adapter 64 is formed with a single turn screw-thread 68. A clamping collar 70 fits on the outside of the lip 66 and co-operates with the adapter. As clearly shown in Figure 2, the marginal portions of the lid 18 around the inlet hole 60 and of the inner shell 40 around its inlet hole are clamped between the adapter ring and the clamping collar and the assembly is completed by rivets 72. Thus, the inner shell 40 is secured to the outer shell at the inlet.

A moulded plastics filler cap 74 has a single turn threaded part 76 which enables it to be quickly attached to or detached from the adapter 64.

A moulded plastics outlet pipe 36 (see Figures 7 and 8) has a screw-threaded portion which passes through a hole in a lower part of one wall of the inner shell 40, and a moulded plastics nut 38 fits on the part of the outer pipe 36 which projects inside the shell 40, whereby part of the shell 40 around an outlet hole in that shell is nipped between a collar 80 formed integrally with the outlet pipe 36 and the nut 38. It will be appreciated that it is necessary to fit the nut 38 on the outlet pipe 36, by gaining access to the interior of the inner shell 40 through the inlet opening covered by the filler cap 74. As indicated in Figure 6, the outlet pipe 36 is located above that portion of the bottom side of the inner shell which is not attached to the bottom sustaining element 52.

The outlet pipe 36 may be provided with any known form of valve, which will enable liquid, semi-liquid, powdered or grannular material, to be drained out of the inner shell 40 when required.

An outlet opening 42 is formed in one wall of the outer shell 10, near to the bottom of that wall, to allow access to the outlet pipe 36. It is desirable however to provide support for the outlet pipe 36, and to prevent easy access to the inner shell 40 through the opening 42 so that pointed articles cannot be inserted through the opening 42. One method of achieving these desired features is to provide an inner cover such as that illustrated in 44 in Figure 8, this inner cover being made of sheet steel material, and secured either to the floor of the outer shell 10, or to the wall of that shell in which the opening 42 is formed.

Also, as illustrated in Figure 8, there may be a Z-shaped member 46 which performs the dual function of providing a platform on which the outlet pipe 36 can rest, and a physical barrier closing the opening through the cover 44 under the outlet pipe 36.

As an alternative to the box-like formation of the cover 44, shown in full lines in Figure 8, it may be extended across the full width of the outer shell as indicated in chain-dotted lines.

When the container is to be used, the filling cap 74 is removed, and liquid or other flowable material such as powder can be fed through the inlet into the inner shell 40. That shell expands as it is filled but its dimensions are such, that even when fully filled, it does not exert any severe outward pressure on the walls of the outer shell 10. Since it is desirable to make the outer shell as close a fit as possible around the inner shell however, and bearing in mind that the inner shell is flexible, the inner shell may in fact engage with the outer shell at certain positions.

When the container is to be emptied, it is only necessary to open the tap or valve in the outlet pipe 36. It is however desirable to remove the filling cap 74 before attempting to empty the container.

In Figure 1, corner fittings 90 are shown welded to the chamfered corners of the outer shell at the bottom end, to allow the container to be secured by screws to a pallet 92.

It will be appreciated that various constructional alternatives may be employed without departing from the inventive concept. For instance, the outlet pipe may be located in the bottom of the inner shell, so that the container is emptied through the bottom instead of out through one side wall. Indeed, for some purposes, the outlet pipe may be omitted altogether, if the material to be transported can be sucked out through the inlet. It will be appreciated that if the outlet pipe can be located either in the bottom of the inner shell 40, or omitted altogether, then the bottom sustaining element 52 can be extended across the full width of the outer shell, because it is no longer necessary to leave an unsustained flexible portion of the inner shell to fit around the bulkhead or cover 44.

In the specific example described above, the inner shell is flexible. It should be understood however, that rigid inner shells may be employed, in which case they can either be secured to the inlet opening in similar fashion to that described with reference to Figure 2 of the drawings, or alternatively, can be free standing on the floor provided by the bottom of the outer shell. In the case of a freestanding inner shell or bottle, a screw cap or closure is provided on the inner shell and an inlet hole is formed centrally in the lid of the outer shell to give access to the screw cap or closure.

The rigid inner shell may be provided with an outlet with a tap as described with reference to the flexible inner shell.

When a larger capacity container is required, such as a 2000 litre container, the outer shell may comprise two shells such as that described above, placed one on top of the other, but with only a single lid and a single floor (i.e. there is no floor in the upper shell and no lid in the lower shell). To give the required degree of rigidity, a steel strap say 3 inches wide, is welded to the outside of the two shells, the strap surrounding the shells and extending above and below the horizontal joint.

Claims

1. A container for transporting and/or storing flowable material comprises an outer shell of rigid or semi-rigid construction which has a generally prismatic shape and an inner shell to receive the material to be contained, the outer shell being made as a tube open at the top and bottom ends and having a closure element secured to one of the open ends by a rolled seam joint.

2. A container as claimed in Claim 1, in which the closure element comprises a lid or a bottom which itself substantially closes that end of the tube.

3. A container as claimed in Claim 1 or Claim 2, in which part of each wall of the tube projects beyond the rolled seam joint and is turned over onto the outside of the closure element to secure that element to the tube.

4. A container as claimed in Claim 1, in which the closure element comprises a support permanently attached to the tube by the rolled seam joint, to which a lid can be releasably secured.

5. A container as claimed in Claim 4, in which the support comprises a frame which fits into the open top end of the tube, and provided with a series of screw threaded parts, the lid having a turned down rim which fits outside the walls of the tube when the lid is in position, and a series of screws passing through holes in the lid and engaging respectively in the screw-threaded parts of the support to releasably secure the lid to the support.

6. A container as claimed in any one of Claims 1 to 5, and having a lid, in which inlet holes are formed in the lid and the top of the inner shell and the marginal portions of both the lid and the inner shell around these inlet openings are nipped together, whereby the inner shell is attached to the outer shell.

7. A container as claimed in any one of Claims 1 to 6, in which the inner shell is made of flexible material.

8. A container as claimed in Claim 7, in which the flexibility of the inner shell construction is such that it will at least partially collapse when empty, but it is capable of expansion to a maximum internal volume when filled with a flowable material, and it is strong enough not to suffer substantial stretching due to stress applied by the internal load when it is full.

9. A container as claimed in Claim 8, in which the inner shell is made in plastics film or thin sheet material having the required degree of strength and flexibility.

10. A container as claimed in Claim 9, in which the inner shell is made of cross-laminated high and low density polyethylene film.

11. A container as claimed in Claim 9 or Claim 10, in which the inner shell is made of co-extruded films, having two or more layers of materials with differing physical properties.

1 2. A container as claimed in any one of Claims 7 to 11, in which the inner shell has a rigid or semi rigid planar sustaining element secured to one of its sides to resist creasing of that side.

1 3. A container as claimed in Claim 12, in which the planar sustaining element comprises a sheet of card such as cardboard, boxboard, millboard, strawboard and the like, secured to the side of the inner shell by adhesive.

14. A container as claimed in any one of Claims 1 to 1 3, in which the outer shell is of generally rectangular prismatic shape.

1 5. A container as claimed in any one of Claims 1 to 14, in which the outer shell has secondary formations to give it additional strength.

16. A container as claimed in Claim 15, in which the outer shell has diagonal or chamfered corners.

1 7. A container as claimed in Claim 6, or any one of Claims 7 to 1 6 so far as they depend from Claim 6, in which the marginal portions of the lid and the inner shell are nipped between a flange on an inlet adapter and a collar, so that the attachment of the inner shell to the outer shell is provided by the adapter and collar combination.

18. A container as claimed in any one of Claims 1 to 17, in which the walls of the outer shell comprise two L-shaped members (as seen in plan) joined together so that each arm of each "L" forms a side wall of the shell and the joints are at diagonally opposite corners.

1 9. A container as claimed in any one of Claims 1 to 18, in which an outlet opening is formed in one wall of the outer shell near to the bottom of the container, for an outlet pipe and/or tap.

20. A container as claimed in Claim 19, in which there is provided a substantially imperforate rigid barrier on the inside of the outlet pipe to protect the inner shell against damage by anything inserted through the outlet opening.

21. A container as claimed in Claim 19, in which the outlet is formed in the bottom wall of the inner shell to permit removal of the contents of the inner shell through the bottom of the container.

22. A container constructed and arranged substantially as herein described with referpence to Figures 1, 2, 3, 4, 6, 7 and 8 or 1, 2, 5, 6, 7 and 8 of the accompanying drawings.