GB2433736A

GB2433736A - Dunnage bag

Info

Publication number: GB2433736A
Application number: GB0522774A
Authority: GB
Inventors: Mark E Prentice
Original assignee: Checkmate UK Ltd
Current assignee: Checkmate UK Ltd
Priority date: 2005-11-09
Filing date: 2005-11-09
Publication date: 2007-07-04
Also published as: GB0522774D0

Abstract

A dunnage bag (10) consists of two sheets (18, 20) of nylon reinforced rubber material bonded together about a common peripheral edge (12), to form a closed bag (10). A filling aperture (14, 16) is provided between the two sheets of material (18, 20), preferably in the corner of the bag (10). Preferably a valve (14) is fitted in the filling aperture (14, 16) and permits inflation of the bag (10) in one mode of operation, and emptying of the bag (10) in another, the valve (14) preferably having a one-way air restriction in one position. The bag (10) may be manufactured by placing two sheets (18, 20) of rubber material on top of one another with a sheet of separator material (22) between the parts of the sheets which are not to be bonded together.

Description

Dunnage Bag This invention relates to dunnage bags used to secure cargo

in cargo containers. In most cases, the container will be a cargo hold of a ship, but the invention may find application in, for example, shipping containers or goods lorries. The dunnage bags are air-filled cushions placed between the cargo items to be secured, and between cargo items and walls of the cargo space.

Dunnage bags often have to be inserted, in an uninflated condition, into narrow gaps between cargo items. Sometimes the bags are to be inserted between cargo layers below a top layer, and it is desirable to have access to the valve to inflate the bag after it has been inserted in this way.

According to the invention, there is provided a dunnage bag comprising two sheets of nylon reinforced rubber material bonded together around a peripheral edge to form a closed bag, and a filling aperture fitted in the peripheral edge between the two sheets of material and through which the bag can be inflated.

It is particularly advantageous if the aperture is at a corner of the bag.

The aperture preferably takes the form of a metal tube bonded into a tapered rubber insert which can be bonded between the two sheets of rubber material.

and a valve is preferably fitted in the aperture. The valve may be operated in one mode, to allow air to enter the bag from a source of pressurised air and in another mode to allow air to escape from the bag.

The bag can be manufactured by placing two sheets of rubber material on top of one another, with a sheet of separator material between the parts of the sheets which are not to be bonded together, placing a tapered rubber insert between the sheets at an edge location, placing the assembly in a vacuum oven and applying heat and pressure to bond the edges of the sheets to each other and to bond the edges to the tapered insert to produce an airtight joint between the sheets and between the sheets and the insert.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of an inflated dunnage bag in accordance with the invention; Figure 2 is an exploded view of the bag prior to assembly; Figure 3 is a perspective view of an insert; Figure 4 is a partial cross-section through the bag at the location of the insert; Figure 5 is an exploded view of the components shown in Figure 4; and Figure 6 is a cross-section through part of the valve.

The bag 10 has a peripheral edge 12 where two sheets of material are bonded to one another to form an airtight joint. A valve 14 passes between the sheets, through a tapered insert 16 which itself is bonded to both sheets.

Figure 2 shows how the bag is made up. A top sheet 18 and a bottom sheet 20 are both the same size. The sheets are made by calendaring a layer of rubber on both sides of a nylon mesh web. A separator sheet 22 is placed between the two sheets before they are bonded together, to ensure that only the sheet edges are bonded, and not the central parts of the sheets. Thus, the dimensions of the separator sheet are the same as those of the two sheets, less the width of the peripheral edge 12, the boundary of which is indicated by dotted lines in Figure 2. After manufacture, the separator sheet remains passively inside the bag. The insert 16 is placed between the top and bottom sheets, and within the area of the peripheral edge, at the position indicated at 21.

Dunnage bags are typically 1 metre or more in both dimensions.

The insert 16 is shown in more detail in Figure 3. The insert is made of a rubber material compatible with the material of the sheets 18, 20 and has an aperture 24 which runs right through the insert.

To make the bag, the four components shown in Figure 2 are placed in position and are then placed inside a vacuum bag, and the bag is placed in an oven.

Air is extracted from the vacuum bag which has the effect of pressing the contacting edges of the sheets 18, 20 and of the insert 24 against one another, and the temperature is raised to a temperature at which the rubber surfaces cure and bond permanently to one another. Typically this temperature will be in the region of I 50C. The separator sheet prevents bonding in other areas.

Once the bonding process is complete, the bag is removed from the oven. A metal tubular sleeve 26 is inserted into the aperture 24 and bonded in place, for example using an epoxy adhesive.

The sleeve 26 has a shoulder 28 which butts up against the insert 16, and an externally threaded head 30. A venting collar 32 screws onto the head 30, and a check valve nipple 34 screws into the collar 32. The nipple 34 is designed to accept a standard "push-on" air hose coupling and incorporates a one-way valve.

The valve 34 is screwed into the collar 32, and a washer 38 lies aginst the end face of the valve 34. In the filling position (shown in the bottom half of Figure 6), the bag can be inflated by attaching an air hose to the nipple 34 and a sealed air flow passage exists through the fitting. To deflate the bag, the collar 32 is unscrewed, taking with it the valve 34, so that the shoulder 36 lifts off the head 30. Once the seal between the internal shoulder of the collar and the head is broken, air can flow out through the radial holes 40 in the collar 32 (top half of Figure 6), and the collar and valve can be screwed back up again when the bag is to be reinflated.

By mounting the valve in the corner of the bag, it will be accessible even when the bag is in place between cargo items. In fact it may even be possible to access the valve of a bag position between cargo some way down in a cargo stack. Because the valve is fitted between the sheets 18,20 there is no need to cut a hole in one of these sheets and as a result, the completed bag is stronger than conventional bags where a valve is fitted through a hole in one or other of the sheets.

It is important that the bags be thin when uninflated, so that they do not themselves unnecessarily take up cargo space and so that they can be inserted into narrow gaps. The sheets 18,20 will have a thickness of 2mm or less. When in use, the bags will usually be inflated to a pressure of 0.4 bar, and will be designed with a burst pressure of 2.5 bar or less.

The reinforced rubber used for the bags is very robust and thus the bags can be used over and over again.

Claims

Claims 1. A dunnage bag comprising two sheets of nylon reinforced

rubber material bonded together around a peripheral edge to form a closed bag, and a filling aperture fitted in the peripheral edge between the two sheets of material and through which the bag can be inflated.

2. A dunnage bag as claimed in Claim 1, wherein the aperture is at a corner of the bag.

3. A dunnage bag as claimed in Claim I or Claim 2, wherein the aperture takes the form of a metal tube bonded into a tapered rubber insert which itself is bonded between the two sheets of rubber material.

4. A dunnage bag as claimed in Claim 3, wherein a valve is fitted in the aperture.

5. A dunnage bag as claimed in Claim 4, wherein the valve may be operated in one mode, to allow air to enter the bag from a source of pressurised air and in another mode to allow air to escape from the bag.

6. A dunnage bag as claimed in any preceding claim, wherein the bag is manufactured by placing two sheets of rubber material on top of one another, with a sheet of separator material between the parts of the sheets which are not to be bonded together, placing a tapered rubber insert between the sheets at an edge location, placing the assembly in a vacuum oven and applying heat and pressure to bond the edges of the sheets to each other and to bond the edges to the tapered insert to produce an airtight joint between the sheets and between the sheets and the insert.

7. A dunnage bag as claimed in any preceding claim, having overall dimensions of at least 1 metre by 1 metre.

8. A dunnage bag as claimed in any preceding claim having a thickness of between 4 mm and 6 mm.

9. A dunnage bag as claimed in Claim 3, wherein the valve has a one-way flow restriction to allow air to flow into the bag but not out, and the valve can be moved between a first position where the valve is closed and a second position where air can be vented from the bag.

10. A dunnage bag substantially as herein described with reference to the accompanying drawings.