WO2004052755A1

WO2004052755A1 - Container

Info

Publication number: WO2004052755A1
Application number: PCT/DK2003/000840
Authority: WO
Inventors: Thomas G. Eriksen
Original assignee: Mærsk Container Industri As
Priority date: 2002-12-09
Filing date: 2003-12-09
Publication date: 2004-06-24
Also published as: AU2003302904A1

Abstract

A double-walled freight container with a frame that comprises upper and lower longitudinal girders and vertically upright corner posts and with sidewalls consisting of an inner sheathing and an outer sheathing, wherein the outer sheathing of the sidewalls is combined of an upper plate panel that extends between the corner posts of he container and is connected to a lower plate panel that extends between the corner posts.

Description

Container

The invention relates to a wall construction for a double-walled freight container.

Often freight containers are exposed to rough handling. Collisions with other containers or other objects eg lift trucks, in connection with reloading and transport are unavoidable. Therefore it is important that a freight container has the requisite strength to withstand the forces to which it may be exposed in such situations.

Typically freight containers consist of a frame between which wall, bottom and ceiling faces are arranged. The frame consists of upper and lower longitudinal girders at each side, upper and lower transversal girders at each end, and vertically upright corner posts. Thus, for instance along the longitudinal direction of the bottom, a longitudinal girder extends, a so-called bottom-side rail. It is typically equipped with one or more longitudinally extending flanges or the like that extend vertically upwards from the lower longitudinal girder. To these flanges the sidewalls of the container are secured. In particular in connection with refrigerated containers the walls are configured as double-walls, ie as a sandwich-construction of two metal plates, ie an inner sheathing and an outer sheathing, and featuring an interposed insulating layer.

It has been found that, during handling, freight containers are most often exposed to impacts against the lower part of the side walls. Another situation that often occurs is that the freight container is put down on hard objects, eg stones or rocks that are present in the reloading and storage areas. In these situations, the freight containers are exposed to forces, in particular in that area where the bottom-side rail and the sidewall are connected. Far too often this leads to deformation of the lowermost part of the outer sheathing of the sidewall, whereby the connection between wall and side-bottom rail breaks, and a hole may be produced in the container side. In those cases where insulated containers are concerned, eg refrigerated containers, deformations of and breaks in the wall will result in the insulating material letting go of the metal plate in large areas around the break point.

These problems are intended to be solved by an improved, novel wall construction according to the invention, whereby the outer side wall is divided into two essentially horizontal plate panels, and upper one and a lower one. The upper panel is of the same type as the prior art construction for side walls for double-walled freight containers, while the lower plate panel consists of a a flexible plate element for absorbing forces from impacts from below or from the side.

By this construction it is accomplished that the forces to which the container is exposed, either from below or from the side, will, rather than leading to container fractures in the area where the wall face and the lower longitudinal girder are connected, be absorbed as deformations in the flexible plate element.

In the following the invention will be explained in further detail with reference to the figures, wherein

Figure 1 shows a double-walled freight container with a sidewall having an upper and a lower plate panel;

Figure 2 shows the container shown in Figure 1 , seen from the side;

Figure 3 shows a lower plate panel with longitudinally extending corrugations; Figure 4 shows a cross section through a part of the container shown in Figure 1 of an embodiment of the invention; and

Figure 1 shows a αouble-walled freight-container comprising a frame consisting of upper^ρ8 and lower 9 longitudinal girders, upper 10 and lower 11 transversal girders and vertically upright corner posts 12. Between said corner posts 12, sidewalls, the top face and the bottom face as well as end walls are tightly fastened. Typically the frame parts and the wall faces are joined by welding. The undersides of the vertically upright corner posts 12 form a resting face P for the container as will appear from Figure 2.

As will appear from Figure 4, the sidewalls, the bottom and the top are double walled structures, ie they are constructed as a sandwich-structure of two plates, ie with an inner sheathing 2 and an outer sheathing 3. Between the inner sheathing and outer sheathing an insulating layer 4 is arranged. Insulating layers typically consist of a foamed plastics material that adheres to the metal plates in the sandwich structure. Typically the inner sheathing 2 is of light metal, eg an aluminium plate. Typically, the outer sheathing 3 consists of stainless steel.

In order to obtain a reinforced, but flexible and light construction, the outer sheathing 3 of the sidewall of the container according to the invention consists of the outer faces of upper 8 and lower 9 longitudinal girders and of the outer, upper plate panel 5 of the sidewall as such, and of a lower plate panel 13 inserted between the upper plate panel 5 and the lower longitudinal girder 9.

The lower plate panel 13 is provided with series of longitudinally extending corrugations 14. These corrugations impart flexibility to the lower plate panel 13, as the corrugations absorb forces from impacts against the side and the bottom of the container. The forces are absorbed in the corrugations, optionally as permanent deformations and hence the connection between the wall face 5 and the lower longitudinal girder 9 is protected. It has been found that even one corrugation increases the flexibility, although more corrugations, eg 2-5 corrugations, are preferred. A further advantage of the longitudinally extending corrugations is that they impart a higher degree of rigidity to the lower plate panel 13 that facilitates handling of the lower plate panel 13 when the container is assembled.

According to a preferred embodiment the lower plate panel 13 is configured with a thickness that exceeds the thickness of the upper plate panel 5. Thereby increased strength is obtained without increasing the container weight excessively.

Typically the thickness of the upper plate panel is 0.7 mm. This thickness can also be used for the lower plate panel 13, but there a thickness of between 1.5 and 10 times the thickness of the upper plate panel 5 is preferred, also in case a thickness is used that is different from the one mentioned. Typically the preferred thickness is comprised within the range of between 1 mm and 2 mm.

Figure 4 shows a transversal sectional view through a double-walled container according to a preferred embodiment of the invention. The lower plate panel 13 is a separate plate panel connected upwardly to the upper plate panel 5 and downwardly to an outer face of the lower longitudinal girder 9. As will appear from Figure 4, the lower plate panel 13 is preferably configured with a smaller material thickness than the lower longitudinal girder 9. The connection 20 between the lower plate panel 13 and the upper plate panel 5 is preferably formed by welding. The connection 21 between the lower plate panel 13 and the lower longitudinal girder 9 is preferably also formed by welding. Having a lower plate panel 13 as a separate plate panel accomplishes that the thickness of the lower plate panel 13 can be optimised such that the requisite strength and flexibility can be obtained without, however, increasing the container weight considerably.

As will appear from Figure 4, the corrugations 14 in the lower plate panel 13 is preferably made as large corrugations 14, whereby these forces are more readily absorbed than in case of small corrugations. In that these corrugations 14 are formed in a plate panel having a thinner thickness than the lower longitudinal girder 9, increased flexibility is provided with an ensuing ability to absorb thrusts in the corrugations.

The lower plate panel 13 is intended to constitute a part of the area of the outer sheathing 3 only. This area must be large enough to cover the area where the majority of the possible damage due to thrust may occur; viz at the bottom of the container or at the lower part of the sidewall, most often in proximity of the centre of the container. At the same time, the area must be minimised for the sake of the container weight. It has been found that the best results are obtained if the joint between the upper plate panel 5 and the lower plate panel 13 is situated at a height of from 350 mm and 1500 mm above the resting face P, and that the corrugations are situated at a height of between h1=350 mm and H2= 1000 mm above the resting face P.

It has moreover been found that it is not necessary that the lower plate panel 13 extends all the way between the corner posts 12; but rather that it needs to cover only particularly exposed areas: for instance it may perceivably extend across an area of up to 2 m to each side of the centre of the container 1.

According to a preferred embodiment the upper plate panel 5 is provided with vertical corrugations to impart rigidity to the container. In the above-described embodiments of the invention the lower plate panel is used for the sidewall of a double-walled container 1. It is also an advantageous option to use a plate panel like the lower plate panel 13 as an intermediate element between other wall faces and frame elements, eg in the bottom face, the top face or an end face in those cases where it can be foretold that a container would be exposed to thrusts in said regions.

The invention also comprises a double-walled freight container 1 with a frame that comprises upper and lower longitudinal girders 8, 9 and vertically upright corner posts 12 that define, at their bottom, a resting face P for the freight container, and with sidewalls consisting of an inner sheathing 2, an outer sheathing 3 and an interposed insulating layer 4, wherein the outer sheathing of the sidewall is combined of an upper plate panel 5 that extends between the corner posts and is connected to a lower plate panel 13 that extends between the corner posts 12, said lower plate panel 13 having a thickness that exceeds the thickness of the upper plate panel 5, and wherein the joint between the lower plate panel 13 and the upper plate panel 5 is situated at a height of between 350 mm and 1500 mm above the resting face P. The lower plate panel 13 is provided with corrugations 14.

Claims

C l a i m s

1. A double-walled freight container (1) with a frame that comprises upper and lower longitudinal girders (8, 9) and vertically upright corner posts (12) defining at their bottom a resting face P for the freight container; and with sidewalls consisting of an inner sheathing (2), an outer sheathing (3) and an intermediate insulating layer (4), characterised in that the outer sheathing of the sidewalls is combined of an upper plate panel (5) that extends between the corner posts and is connected to a lower plate panel (13) that extends between the corner posts (12), said lower plate panel (13) having at least one longitudinal corrugation (14) arranged at a distance of between 350 mm and 1000 mm above the resting face (P).

2. A double-walled freight container according to claim 1 , characterised in that the insulating layer (4) of the container is adhered at least to the outer sheathing (3).

3. A double-walled freight container according to claim 1 or 2, characterised in that the lower plate panel (13) has a thickness that exceeds the thickness of the upper plate panel (5).

4. A double-walled freight container according to claim 3, characterised in that the lower plate panel (13) has a thickness which is between 1.5 and 10 times the thickness of the upper plate panel (5).

5. A double-walled freight container according to claim 3, characterised in that the lower plate panel (13) has a thickness of between 1 and 2 mm.

6. A double-walled freight container according to any one of claims 1-5, characterised in that the upper plate panel comprises vertical corrugations

(15).

7. A double-walled freight container according to any one of claims 1-6, characterised in that the lower plate panel (13) has a thickness that exceeds the thickness of the lower longitudinal girder (9).

8. A double-walled freight container according to any one of claims 1-7, characterised in that the lower plate panel (13) is connected to the lower longitudinal girder (9).

9. A double-walled freight container according to any one of claims 1-8, characterised in that the lower plate panel (13) is connected to the corner posts (12).

10. A freight container according to any one of claims 1-8, characterised in that the lower plate panel (13) is connected to the corner posts via a plate panel that is connected to the upper plate panel (5) and the upper and lower longitudinal girders (8,9).