GB2168679A

GB2168679A - Flexible bulk container

Info

Publication number: GB2168679A
Application number: GB08432133A
Authority: GB
Inventors: Frank Nattrass
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-12-19
Filing date: 1984-12-19
Publication date: 1986-06-25
Also published as: GB8432133D0

Abstract

A bulk material container has a base (2); means at the top of the container by way of which it may be lifted; and an inner liner (3) within the container for receiving the load. The base is provided with a central outlet opening (4) and a tube (5) projects downwardly from the base and surrounds the central opening. A drawstring (12) located inwardly of the tube is guided by guide means (e.g. 8, 10) such that as the drawstring is tightened it is constrained to take up a central position within the central opening. The inner liner has a tail section (14) projecting through the central opening and the drawstring has the freedom to tighten to grip the tail section so as to centralise this. There are means (15) for releasably closing the tail section below the central opening, and means (6) for releasably closing the outer tube with the tail section contained therein. <IMAGE>

Description

SPECIFICATION Bulk material containers This invention relates to bulk material containers.

There are many different types of bulk material containers in the form of large bags now available, such containers being used for the transport and storage of, for example, bulk quantities of powdered or granular material.

Such containers are available in the capacity range of from about half to two tonnes. One requirement of such containers, if they are to be re-usable, is that they must be equipped with outlet means which will permit simple and rapid discharge of the contents.

There have been a number of different proposals for outlets from such containers, and to some extent these have met certain of the requirements.

However, one problem that is commonly experienced occurs with the type of container that includes an inner liner within the main body of the container, the load actually being filled into the inner liner and thereby receiving additional protection. In one known form of discharge arrangement the inner liner has a tail section protruding through a central opening in the base of the bag into a tube structure surrounding that central opening. Different types of arrangements have been proposed for closing the tail end and for securing this in position within the tube structure. These closures are effected before the contents are loaded into the container, and when those contents are to be discharged then the various closures are released so that the material may flow from the inner liner through the tail section thereof.

During manufacture of the container the workman is free to tie off the tail end and secure this within the tube structure without any constraint on the locations of tying off and securing. A common fault is to tie off and anchor the tail end of the liner in such a way that it lies adjacent to the periphery of the hole in the base of the bag. Liners are often twisted during assembly and the result of both of these conditions is that when the bulk material is loaded into the liner the twists are forced into a concentration at the bottom of the liner, just above the location where the tail section is tied off. This twist concentration forms a short, stiffish column which under the weight of the contents is able to bend over and become trapped against the inner surface of the base of the bag.Under these conditions it is impossible to free the tail end of the liner when it is required to discharge the contents, and the only way discharge can be effected is to cut the liner. As a result, all possibility of controlled discharge is removed.

The present invention seeks to overcome this problem.

According to the invention I provide a bulk material container having a base; means at the top of the container by way of which it may be lifted; and an inner liner within the container for receiving the load, in which the base is provided with outlet means comprising a central opening in the base, a tube projecting downwardly from the base and surrounding the central opening and a drawstring arrangement located inwardly of the tube and including a drawstring and, means guiding the drawstring so that as the drawstring is tightened it is constrained to take up a central position within the central opening; the inner liner having a tail section projecting through the central opening and the drawstring having the freedom to tighten to grip the tail section of the inner liner so as to centralise such tail section; means for releasably closing the tail section below the central opening and means for releasably closing the outer tube with the tail section contained therein.

In such an arrangement the tail section of the liner is positively centralised in the opening of the base of the bag. Thus, even if twist is present in the liner the loading of material will force the twist into a concentration at the bottom of the liner that is again located substantially centrally within the opening and that thus cannot become trapped between the base of the bag and the contents of the bag.

The tail end of the liner is thus free to be drawn from the bottom of the bag and loosened off for discharge of the material, the twist running out of the tail section of the liner during such discharge. The problem of trapping the liner is thus avoided.

It must be emphasised that the drawstring must have the freedom to tighten sufficiently far so as positively to grip the tail section, as only by this step will the tail section be centralised within the opening. Drawstring constructions that cannot so be tightened will leave open the possibility of improper location and clamping of the tail section of the liner, with the possibility of trapping the liner.

Many different types of drawstring arrangement are possible. In a first form of the invention a plurality of loops may be secured to the periphery of the opening within the tube, the drawstring passing through each of the loops and the loops being of equal length sufficient to extend substantially to the centre of the opening. The drawstring is passed through all the loops, so that when tightened it centralises in the opening and can grip the tail section of an inner liner projecting therethrough.

In a second embodiment a second tube may be included within the first tube, the second tube terminating in an opening which incorporates a drawstring around the neck thereof.

The drawstring may be included in the usual form of narrow drawstring tunnel extending around the neck, or more desirably the tube may be formed from a single piece of material folded double with the fold around the neck and the drawstring lying between the two plies of material. In a particularly advantageous form of the invention the second tube and the main tube may be formed from a single length of fabric.

In order that the invention may be better understood embodiments of container in accordance therewith will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a cross-section through a first type of discharge arrangement; Figure 2 is a schematic representation of the arrangement of Figure 1 shown in perspective from the interior of the container; Figure 3 is a view corresponding to Figure 1 showing the outlet in an alternative condition; Figure 4 is a view corresponding to Figure 1 of a second embodiment of outlet; Figure 5 is a view corresponding to Figure 3 of the outlet shown in Figure 4; and Figure 6 is a view corresponding to Figure 1 of a third embodiment of outlet.

Figure 1 shows a bulk material container in the form of a flexible bag 1 having a base 2.

The bag has means at the top thereof by way of which it may be lifted. The lifting means may be in any one of a number of different forms, and is not shown as it forms no part of the invention. An inner liner 3 is included within the bag, and is generally of a plastics or other material that is impervious to moisture and thus protects the contents and also prevents contents possibly migrating through woven fabric which may form the bag.

The base of the bag is formed with a central opening 4, and a tube 5 is stitched to the fabric of the base around the periphery of the opening. The tube is formed from a single piece of material folded double as shown, and a drawstring 6 lies between the two plies of material and has ends 7 brought through holes in the outer ply of material in the usual way.

Four loops 8 to 11 are stitched at equal angu lar intervals to the periphery of the opening and are located within the tube 5. The loops are of equal length, which is in each case sufficient for the loop to extend substantially to the centre of the opening. A drawstring 12 is passed through all of the four loops and has free ends 13. The inner liner 3 has a tail section 14 which can extend through the opening in the base of the bag and through the tube 5 to project beyond that tube as shown in Figure 1.

Figure 1 shows the bag after manufacture thereof and after fitting of the inner liner therein. To make the bag ready for use a removable clip or tie 15 is fitted around the tail section of the inner liner in order to close this off. The drawstring 12 is then tightened, so lifting the loops 8 to 11 into the plane of the opening 4, centralising the drawstring in the opening and tightening the drawstring around the tail section 14 in order positively to grip this tail section. As a result thereof, the tail section will also be centralised in the opening. The free length of tail section 14 may then be rolled up as shown in Figure 3 and the drawstring 6 tightened in order to close the opening of the tube 15 with the tail section located within the closed tube and so protected from dirt and damage.

When the bag is in the condition shown in Figure 3 it may be filled with the material to be transported. If the inner liner has been twisted during insertion into the bag, which often happens, then during filling that twist is forced into a concentration at the bottom of the liner, just above the location where the tail section is tied off. This twist concentration forms a short, stiffish column, which may bend over under the weight of the load and take up the condition shown at 16 in Figure 3. Because of the centralising of the tail section of the tube within the opening 5 it will be noticed that the column does not extend to a position wherein any part of it overlies the fabric 2 of the base of the bag.

When it is required to discharge the contents from the bag the bag is suspended from its lifting means and the drawstring is released so that the tube 5 can be opened. The tail section 14 of the liner is brought downwardly through the tube 5. The drawstring 12 is then released, so freeing the twist column and enabling the tail section to be untwisted. The untwisted tail section may then, if discharge into a hopper is required, be placed around the hopper entry and secured thereto in order that discharge may be dust-free. Finally, the clip or tie 15 is removed and the contents of the bag are then free to flow through the tail section to be discharged from the bag. Control of the rate of flow may be effected by adjusting the degree of tightening of either or both of the drawstrings 12 and 6 in order to restrict the diameter of the tail section.

Positive centralisation of the tail section in a central opening of sufficient diameter ensures that even if twist columns are formed in the liner they will not be trapped between the load and the base of the bag. As a result it is not necessary to mutilate the liner in any way in order to discharge the bag's contents, with the result that control of that discharge is not lost.

Referring to Figures 4 and 5 these show an alternative form of container in the form of a bag 21 having a base 22 with an opening 23.

Two tubes, an outer tube 24 and an inner tube 25 are stitched around the periphery of the opening 23, each tube being formed from a single thickness of fabric. The inner tube 25 has its free end turned back upon itself to form a tunnel in which is located a drawstring 26, the free ends of which are brought to the outside of the tube through the holes in the tube in the usual way. The bag has an inner liner 27 with a tail section 28 of sufficient length to project through the two tubes 24 and 25.

Before filling this bag the tail section 28 is closed by a clip or tie 29 and the drawstring 26 is tightened in order to close the tube 25 and draw this into the plane of the opening, the drawstring centralising and tightening around the tail section 28 so that this is centralised in the opening. The length of the tube 27 is such as to give the drawstring the necessary degree of freedom so that it may tighten positively around the tail section 28.

The free part of the tail section 28 is then rolled up and the outer tube 24 is closed by a clip or tie 30 as seen in Figure 5. If the liner is twisted then, when the container is filled the twist column will overlie part of the tube 25 rather than part of the base 22 of the bag, in a manner analagous to that described for Figure 3.

The contents may be discharged from the bag in a manner again similar to that which has already been described. The clip or tie 30 is removed and the end of the tail section 28 is unrolled. The drawstring-26 is loosened so freeing the tail section so that any twist in the bottom of the liner may be removed by untwisting that section. The tail section may then be secured around the entrance to a hopper and the clip or tie 29 removed so that the contents may be discharged into the hopper.

A degree of control may be effected by appropriately tensioning the drawstring 26.

A further embodiment of container is shown in Figure 6 in the form of a bag 41 having a base 42 and inner liner 43 with a tail section 44. The base of the bag has a central opening 45 and stitched to the periphery of the central opening is a pre-formed twin tube assembly comprising an outer tube 46 and an inner tube 47. The two tubes are formed from a single piece of material folded double and drawstrings 48 and 49 are included around the neck of each of the two tubes. The ends of the drawstrings issue through holes in the outer plies of the material of the tubes. In use a clip (not shown) is secured to the tail section and the drawstring 49 is tightened to centralise the tail section in the opening 45.

Thereafter the tail section is rolled up and the tube 46 closed by tightening the drawstring 48. Discharge may be effected in a manner analagous to that already described. The degree of freedom that is given to the movement of the two drawstrings in this embodiment by the large open area within each of the tubes greatly facilitates manipulation of the drawstrings.

It will be appreciated that the drawings show only examples of the ways in which the invention can be put into practice, and other drawstring arrangements which have the effect of centralising the tail section of an inner liner are possible.

Claims

1. A bulk material container having a base; means at the top of the container by way of which it may be lifted; and an inner liner within the container for receiving the load, in which the base is provided with outlet means comprising a central opening in the base, a tube projecting downwardly from the base and surrounding the central opening and a drawstring arrangement located inwardly of the tube and including a drawstring and means guiding the drawstring so that as the drawstring is tightened it is constrained to take up a central position within the central opening; the inner liner having a tail section projecting through the central opening, and the drawstring having the freedom to tighten to grip the tail section of the inner liner so as to centralise such tail section; means for releasably closing the tail section below the central opening and means for releasably closing the outer tube with the tail section contained therein.

2. A container according to claim 1 in which a plurality of loops are secured to the periphery of the opening within the tube, the drawstring passing through each of the loops and the loops being of equal length sufficient to extend substantially to the centre of the opening.

3. A container according to claim 2 in which four loops are provided, spaced at substantially equal angular intervals around the opening.

4. A container according to claim 1 in which a second tube extends from the opening and lies within the first tube, the second tube terminating in a second opening and the drawstring being incorporated around the neck of the second opening.

5. A container according to claim 4 in which the drawstring lies in a drawstring tunnel extending around the neck of the second opening.

6. A container according to claim 4 in which the tube and the second tube are together formed from a single piece of material folded double, and the drawstring lies between the two plies of material.

7. A bulk material container substantially as herein described with reference to Figures 1 to 3, to Figures 4 and 5 or to Figure 6 of the accompanying drawings.