WO2012114101A2

WO2012114101A2 - A blast-resistant structure

Info

Publication number: WO2012114101A2
Application number: PCT/GB2012/050392
Authority: WO
Inventors: Michael John Sargeant; David J FANNON
Original assignee: Renew Pod Limited
Priority date: 2011-02-23
Filing date: 2012-02-22
Publication date: 2012-08-30
Also published as: GB2488344A; GB201103112D0; WO2012114101A3

Abstract

A blast-resistant structure comprising a body in which is defined an aperture is disclosed. The aperture is bounded by two edge parts of the 5 body. The blast-resistant structure further comprises a door configured selectively to close-off the aperture, and first and second securing mechanisms configured selectively to secure the door to respective ones of the body edge parts. Each securing mechanism comprises a locking channel associated with the body and a corresponding locking pin 10 associated with the door. Each locking pin is moveable between an open position in which the locking pin is external to the locking channel and a secured position in which the locking pin is engaged in the locking channel. The locking channel has a generally rectangular cross-section that is defined on at least first and second sides by a locking pin retention 15 part. Furthermore, the locking pin retention parts and the locking pins are formed of sheet material.

Description

A Blast-resistant Structure Field

The present invention relates to a blast-resistant structure. Background

Refuse bins are typically provided in public places in town and city centres. However, security concerns have resulted in the removal of refuse bins from some public areas causing inconvenience to the public and an increase in cost for those charged with litter clearance.

Bomb resistant bins with the ability to contain explosions are known. The design of such bins is challenging because of the usually conflicting

requirements of effectiveness of blast-resistance and cost of manufacture, ease of emptying, ease of use by the public, ease of installation and later removal.

Summary

According to the present invention, there is provided a blast-resistant structure comprising: a body in which is defined an aperture, the aperture being bounded by two edge parts of the body; a door configured selectively to close-off the aperture; and first and second securing mechanisms configured selectively to secure the door to respective ones of the body edge parts, each securing mechanism comprising a locking channel associated with the body and a corresponding locking pin associated with the door, each locking pin being moveable between an open position in which the locking pin is external to the locking channel and a secured position in which the locking pin is engaged in the locking channel, wherein the locking channel has a generally rectangular cross- section that is defined on at least first and second sides by a locking pin retention part, and wherein the locking pin retention parts and the locking pins are formed of sheet material. This can provide suitable strength to the key aspects of the securing mechanisms whilst allowing them to have a relatively simple form and be relatively easy to manufacture.

Preferably, the first and second locking pins are integrated onto a locking pin mechanism such that the first and second locking pins are in a fixed relationship with respect to one another. This can allow improved resistance to blast forces whilst not requiring sophisticated manufacturing techniques.

Conveniently, a first single sheet of material constitutes part of both the first and second locking pins. This can provide suitable strength to the key aspects of the locking pin mechanism whilst allowing it to have a relatively simple form and be relatively easy to manufacture.

The locking mechanism may include at least two layers of sheet material at the locking pins. This can provide good structural rigidity over the parts of the locking pin mechanism where this is particularly important whilst allowing the overall structure to be relatively lightweight.

In one embodiment, the locking pin mechanism comprises two pairs each of first and second locking pins, and wherein the first sheet of material and a second sheet of material constitutes both of the first locking pins and the first sheet of material and a third single sheet of material constitutes both of the second locking pins. This can provide good structural rigidity over the parts of the locking pin mechanism where this is particularly important whilst allowing the overall structure to be relatively lightweight.

Each locking pin may comprise a reinforcing component that is formed of sheet material, the reinforcing component being secured against a first face of the locking pin with a plane of the sheet material of the reinforcing component being generally perpendicular to the first face of the locking pin. This can provide significantly increased strength to the locking pins using sheet material.

Preferably, each reinforcing component includes a bend between a part at which it is secured against the respective locking pin and a part at which it is secured against a part of the locking pin mechanism part that connects the locking pin to another locking pin. This provides significantly increased strength where the locking pin connects with the rest of the locking pin mechanism, and achieves this is a way using relatively simple manufacturing techniques.

In one embodiment, each reinforcing component includes a step profile along one edge and wherein the reinforcing component is secured against the first sheet of material on one side of the step and is secured against another one of the sheets of material on the other side of the step. This allows the reinforcing component to extend for a distance that is greater than the extent of the second and third sheets of material

Conveniently, the locking channel is defined also on a third side by the locking pin retention part. The locking channel may be defined also on a fourth side by the locking pin retention part.

Brief Description of the Drawings

Embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a perspective view of a blast resistant container embodying the present invention;

Figure 2 shows a perspective view of an inner side of a door of the container; Figure 3 shows a perspective view of an inner side of the door of the container without a cover; Figure 4 shows a front view of an outer side of the door shown in Figures 2 and 3;

Figure 5 shows a perspective view of a paper gate fitted to the door;

Figure 6 shows a perspective view of an upper locking plate with locking hooks; Figure 7 shows a perspective view of a lower locking plate with locking hooks; Figure 8 shows a perspective view of a part of either of the locking plates and showing a second layer;

Figure 9 shows a perspective view the same as Figure 8 but with a reinforcing component in place;

Figure 10 shows a perspective view of part of the reinforcing component shown in Figure 9;

Figure 11 shows a perspective view of a cover fitted to an inner side of the door;

Figure 12 shows a perspective view of the container without the door;

Figure 13 shows a perspective view of a locking channel fitted to the inside of the container;

Figure 14 shows a first elongate part of the locking channel shown in Figure 13; Figure 15 shows a second elongate part of the locking channel shown in Figure 14; and

Figure 16 shows a limb with a reinforcing component of the second elongate part.

Detailed Description

Referring now to the drawings, there is shown in Figure 1 a blast resistant container 1 configured to absorb and upwardly direct forces of an explosion originating inside the container 1.

The container 1 comprises a door 2, a rear wall 3, a left and a right side wall 4, 5 and a base 6 defining a space for holding refuse. The rear wall 3, the left and the right side walls 4, 5 are integrally formed, for example, it may be formed of a metal sheet. The door 2 is removably attachable to edges formed at the front of the two side walls 4, 5 so as to provide access to the space provided within the container 1. The door 2 is hinged so that is can be swung open and closed. The hinge axis is vertical, and there is no vertical change in the centre of gravity of the door as it hinges.

The base 6 is formed with a plurality of holes (not shown) for receiving fastening means such as bolts so that the container 1 can be secured to the ground upon which it stands. At an opposite end to the base 6, an aperture 8 is formed for directing or channelling a blast from an explosion in a direction away from the base 6 and generally vertically. The longitudinal axis of the container ι is generally vertical in use.

Referring now to Figures 2 to 5, the door 2 comprises a front panel 20 preferably made out of a metal sheet. The door 2 of the container is provided with a refuse aperture 9 through which a user disposes of their waste so that the waste is received and contained in the space of the container 1. A refuse aperture panel 21 is fitted on the inner surface of the front panel 20 covering the aperture 9. The refuse aperture panel 21 is removably attachable to the refuse aperture 9 and when it is attached to the front panel 20 a user is prevented from disposing of their waste through the aperture 9. This may be necessary in order to put the container temporarily out of use as a bin, in particular during high security alerts. In an alternative embodiment, the refuse aperture panel 21 may be formed with a variety of holes so that the size of the waste received in the space of the container 1 can be controlled.

The door 2 is removably attached to the container 1 by cooperating means. The cooperating means of the door 2 includes locking hooks 28 attached to locking plates 25, 26 which are movable in a direction parallel to the longitudinal axis of the container 1. The locking hooks 28 may also be termed locking pins. The locking plates 25, 26 may also be termed locking pin mechanisms. The locking hooks 28 engage with corresponding cooperating elements, which can be termed locking channels, which are described in more detail below. The cooperating means enable the door 2 to be secured to the left and right side walls 4, 5 of the container 1 such that it is retained in its position in the event of an explosion within the container. Additionally, the cooperating means allow for the door 2 to be opened such as to allow access to the interior of the container 1, in particular when the container is used for refuse and needs emptying or cleaning.

The locking plates 25, 26 comprise an upper 25 locking plate and a lower locking plate 26 which are shown in Figures 6 and 7, respectively, and in situ in Figure 3. Both plates 25, 26 have a rectangular profile and are formed of a respective metal sheet. Centrally positioned apertures 27 of the plates 25, 26 have been cut out. This reduces the weight of the plates 25, 26 as well as the quantity of material required without significantly reducing strength where high strength is most needed. At approximately each corner of each of the plates 25, 26, the locking hooks 28 are formed. The locking hooks 28 each have a longitudinal axis that extends perpendicular to a line connecting opposite locking hooks. The axes of the locking hooks is vertical in use.

An end of an arm 29 is attached to the lower locking plate 26. At an opposite end of the arm 29, a rack 30 having teeth 31 is formed. The arm 29 and the rack 30 extend parallel to the locking hooks 28, so vertically in use. The upper locking plate 25 is also formed with a rack 30 having teeth 31. When the upper and lower locking plates 25, 26 are in the position shown in Figure 3, the rack 30 on the arm 29 extending from the lower locking plate 26 is parallel to the rack 30 formed on the upper locking plate 25. Furthermore, the teeth 31 of the racks 30 are opposing one another. A pinion 32 is located between the racks 30 and is rotatable about a central axis. The pinion 30 engages with the teeth 31 of the racks 30 such that rotation of the pinion causes the racks 30 to move up and down respectively. This causes the plates 25, 26 to be moved in a direction parallel to the longitudinal axis of the container 1. The plates 25, 26 have generally the same configuration, and approximately the same weight. The rack and pinion arrangement results in the plate 25 moving upwards by the same amount as the other plate 26 is moved downwards. Because the plates 25, 26 have about the same weight, the force required to move the plates 25, 26 to activate locking or unlocking is relatively low. Moreover the force required is approximately the same for both the locking and unlocking movements.

The pinion 30 is further formed with holes (not shown) for receiving a corresponding key (not shown) so that the pinion can be rotated so as to lock and unlock the door 2. As shown in Figure 1, a hole 80 is formed in the door 2 exposing the holes in the pinion such that they can be accessed with a corresponding key 81.

The locking hooks 28 of each locking plate 25, 26 face the same direction and lie in the plane of the locking plates 25, 26. However, the locking hooks 28 of the upper locking plate 25 face the opposite direction to the locking hooks 28 of the lower locking plate 26, as is best seen in Figure 3. When the locking hooks 28 engage with the cooperating elements of the container 1 such that the door 2 is secured to said container 1, movement of the door in a bilateral direction parallel to the longitudinal axis of the container is restricted. This increases the blast resistance of the door 2 in contrast to a container wherein the hooks are configured to face the same direction. If the hooks were to face the same direction, movement of a door due to an explosion might only be restricted in a unilateral direction parallel to the longitudinal axis of the container.

Outer portions of the locking plates 25, 26 and the corresponding locking hooks 28 extending therefrom are provided with a second layer 33, as is best seen in Figure 8. Although it is not shown in Figure 8, it should be understood that a second layer 33 is formed on both locking plates 25, 26. As such, each of the locking hooks 28 includes two layers of sheet metal. However, much of the locking plates 25, 26 is formed of only single thickness sheet steel. The second layers 33 lie in a plane parallel to the locking plates 25, 26 and are formed with holes 24. The second layers 33 are secured to the main sheet of the locking plates 25, 26 by fillet welds where the edges of the holes 24 meet the adjacent surface of the main sheet of the locking plates 25, 26. Additionally or alternatively, the second layers 33 are secure to the main sheet of the locking plates 25, 26 in part by fillet welds at the step formed where the second layers 33 end and the main sheet continues. This is achieved also by the way in which reinforcing members are secured, as is described below.

As can be seen best in Figure 9, each outer portion of the locking plates 25, 26 is also reinforced with a reinforcing member 34. The reinforcing members 34 each lie in a plane perpendicular to the locking plates 25, 26 thereby adding additional strength in yet another direction. The reinforcing members 34 of each plate 25, 26 also extend over the tips of the locking hooks 28. This provides further strength to the hooks 28 and facilitates self-guiding of the locking hooks 28 into the cooperating elements. The corners 35 of the locking hooks 28 are tapered, and the tapering may be rounded. This further eases the guiding of the hooks 28 into the cooperating elements of the container.

The second layers 33 and the reinforcing members 34 are joined to the locking plates 25, 26 by means of welding tabs received through holes. In particular, holes 34b are formed in the second layers 33 at locations corresponding to holes in the locking plates 25, 26 as seen in Figure 8. The reinforcing members 34 are formed with tabs 34a, that are best seen in Figure 10. The tabs 34a have a rectangular cross-section, one dimension of which is equal to the thickness of the metal sheet constituting the reinforcing members 34. The other dimension may be larger, for instance up to 150% of the sheet thickness. In this example, the sheet thickness is 6mm and the other dimension of the cross-section of the tabs is 8mm.

The tabs 34a are inserted into the holes 34b of corresponding dimensions. The holes 34b may be a small amount larger than the exterior dimensions of the tabs 34a, for instance. The tabs 34a protrude by a small distance, in this example approximately 1 millimetre, past the opposite side of the locking plates 25, 26. The 1 millimetre protrusions of the tabs 34a are thereafter welded to the locking plates 25, 26. The weld may be a weld material-free weld. Advantageously, the 1 millimetre protrusions are generally levelled with the surface of the locking plates 25, 26 during the welding. Additional fillet welding is performed for some of the junction between the reinforcing members 34 and the second layer 33, and for some of the junction between the reinforcing members 34 and the locking plates 25, 26.

The locking plates 25, 26 and the second layer are preferably formed of metal sheet. In this way, the downsides of using machined, cast etc metal can be avoided. The metal sheet may be cut into shape by laser cutting. The metal sheet may be a high carbon steel, such as a high carbon hardened steel sold under the name Domex™.

The cooperating means of the door 2, the locking plates 25, 26, and the associated locking hooks 28, are held in their position against the inner surface of the front panel 20 by the racks engaging with the pinion 32 secured to the front panel 20. A cover 40 is fitted to the inside of the front panel 20, as is best seen in Figure 2. The cover comprises a main panel 41 having side walls 42 depending therefrom. The side walls 42 along the longitudinal sides of the cover 40 are formed with gaps 43 through which the hooks 28 protrude. The side walls 42 are further formed with tabs 44 as can be seen in Figure 11. These tabs are received in corresponding holes 45 or slots on the front panel 20 of the door 2. The holes 45 can be seen in Figure 4. The tabs are welded to the front surface of the front panel 20. This secures the cover 40 to the front panel 20. The tabs may be levelled by the welding and/or may be dressed after welding.

The inner surface of the front panel 20 is further fitted with two u-profile bent sheet metal bars 36. The bars 36 run adjacent the longitudinal edges of said front panel 20. They are secured to the front panel 20 using a 'slot and tab' system like that described above. Briefly, the bars 36 are formed with tabs (not shown) along their free longitudinal edges that are received in corresponding holes 46 in the front panel 20, as shown in Figure 4. The tabs protrude through the holes to the opposite outer surface of the front panel 20, where the tabs are welded to the outer surface of the front panel. The bars 36 provide support to the outer portions of the locking plates 25, 26 as they are moved up and down. Furthermore, the bars 36 also provide additional structural support to the locking plates 25, 26 in a direction perpendicular to the longitudinal axis of the container in the event of an explosion within the container 1.

The door is also provided with hinges 37 which are received in corresponding holders 38 of the container, thereby enabling a user as they have unlocked the cooperating means to swing open the door 2 to access the space within the container 1.

Referring now to Figures 12 to 16, the cooperating means on the container 1 comprises two locking channel structures 50 which are fixedly attached to the inside of the container 1 adjacent to the free edges of the left and right side walls 4, 5. Each locking channel structure 50 is defined in part by one of first and second elongate components 51, 52 and defines respective locking channels for receiving locking pins 28.

The first elongate component 51 as illustrated in Figure 14 is formed of a sheet of material which is bent such that it comprises four panels 53, 54, 55, 56. The first and the third panel 53, 55 extend in opposite directions away from the second panel 54. The first and the third panel 53, 55 are generally perpendicular to the second panel 54. The first and the third panel 53, 55 may alternatively extend from the second panel 54 at an angle greater or a smaller than 90⁰, as long as they extend in the general opposite direction. The fourth panel 56 extends from the third panel at approximately 90⁰ and in a plane parallel to the plane of the second panel 54. The fourth panel 56 may extend from third panel at an angle greater or a smaller than 90⁰. The first elongate component essentially comprises a generally rectangular metal sheet that includes three bends in the direction of the longest side of the rectangle. The length of the rectangular sheet defines the length of the elongate components.

Approximately half of the width of the metal sheet forms the first and second panels, that ultimately define the locking channel structures 50. The free edge of the first panel 53 is formed with recesses 58 so as to receive limbs 61 of the second elongate component 52. The third panel 55 is formed with holes 70 that allow so as to be welded to the second elongate component 52. Furthermore, the bend connecting the second and third panels 54, 55 are formed with holes 59 for receiving tabs 5yd of the second elongate component 52. As best seen in Figure 14, the fourth panel 56 is formed with tabs 57a for securing the first elongate component 51 channel structure 50 to a planar component such as the outer wall 4.

The second elongate component 52 as illustrated in Figure 15 comprises a first planar part 60 provided with four limbs 61 that are spaced apart from one another and that extend perpendicularly from a longitudinal edge of the first planar part 60. The limbs 61 are bent about an axis parallel to the longitudinal axis of the first planar part 60. The limbs are bent at 90⁰. The limbs 61 are provided with tabs 57b at an edge parallel to the longitudinal axis of the first planar part 60. The aspects of the second elongate component so far described are formed from a single sheet of metal that is first cut into shape before the limbs are bent. The sheet of metal that constitutes the second elongate component 52 is thicker than the sheet that constitutes the first elongate component 51. It will be appreciated that the bends in the second elongate component 52 are shorter than the bends in the first elongate component.

The second elongate component 52 is further provided with reinforcing components 64 that are aligned with each limb 61. The reinforcing components 64 are of similar shape to the limbs 61 and they are bent about an axis parallel to the longitudinal axis of the second elongate component 52. The reinforcing components 64 are formed of sheet metal of the same thickness as the sheet forming the first planar part 60 and the limbs 61. The reinforcing components 64 extend from the edge of each limb 61 that is provided with tabs 57b to the junction of the limbs 61 with the first planar part 60 of the second elongate component 52. At each of the ends, the reinforcing components 64 are provided with at least one tab 57c, 57c!. The end of each reinforcing component 64 that is aligned with the edge of the limbs 61 provided with tabs 57b, is formed with one tab 57c that is off-set relative to said tabs 57b of the limbs 61. The tab 57c of each reinforcing component is off-set in a direction parallel to the longitudinal axis of the second elongate component 52. A gap is provided in the longitudinal direction of the first planar part 60 between the tab 57c and each of the tabs 57a, 57b. The end of each reinforcing component 64 that terminates adjacent the first planar part 60 is provided with two tabs 57d which lie in a plane parallel to that of the first planar part 60. Each reinforcing component 64 is formed with holes 65 and the reinforcing components 64 are secured to their respective limbs 61 by fillet welds where the edges of the holes 65 meet the adjacent surface of said limbs 61. Each reinforcing component 64 may additionally or alternatively be welded to its respective limb 61 along at least some of the outer junctions where the reinforcing component 64 and the limb meet, although not at the two ends of the reinforcing component that are provided with tabs 57c, 57d.

The first and second elongate components 51, 52 are attached to one another such that the edges of each limb 61 provided with tabs 57b and respective reinforcing component 64 locate in the recesses 58 of the first elongate component 51. The tabs 57d of the reinforcing component 64 that are provided at the end adjacent the first planar part 60 are received in the corresponding holes 59 formed in the bend of the second and third panels 54, 55 in the first elongate part 51 of the locking channel. The tabs 57d are welded to the bend connecting the second and third panels 54, 55 of the first reinforcing component 51 so as to secure the first and second elongate components 51, 52. Furthermore, as the tabs 57d of the reinforcing components 64 are received in the holes 59 of the bend between the second and third panels 54, 55, the first planar part 60 locates against a surface of the third panel 55 that faces away from the second and fourth panels 54, 55. The first planar part 60 is welded to the surface of the third panel 55 where the edges of the holes 70 formed in the third panel 55 contact the first planar part. The first planar part 60 may additionally or alternatively be welded along at least part of its length.

The limbs 61 and respective reinforcing components 64 together with the first and the second panels 53, 54 form channels 66 for receiving the locking hooks 28. As the channels 66 are partially defined by structures provided by the limbs 61 and the reinforcing components 64, which structures are spaced apart from one another, gaps 67 are formed between the channels 66. When the door 2 is unlocked, the locking hooks 28 are positioned in the gaps 67 such that the door 2 can be removed from the container 1. When the door is moved into its locked position, the locking hooks 28 are moved in an upward or downward direction parallel to the longitudinal axis of the first and second elongate 51, 52 components such that the locking hooks 28 locate within the channels 66.

The first and second elongate components 52, 52 and the reinforcing

components 64 channel structures 50 are secured to the inner sides of the left and right side walls 4, 5 of the container 1 by the 'slot and tab' welding system described above. In particular, the tabs 57a formed on the fourth panel 56, the tabs 57b provided on the limbs 61 and the adjacent tab 57c on the reinforcing component 64 are all provided by arrangement in the same plane and locate in corresponding holes 68 provided on the left and right side walls 4, 5 of the container 1, as best seen in Figure 12. As the locking channel structures 50 are positioned on the inside of the left and right side walls 4, 5 the tabs extend from the inside of the container to an outer surface of each side wall 4, 5. The tabs protrude by approximately 1 millimetre past the outer surfaces of each side wall 4, 5. This enables the tabs to be welded to and levelled with the outer surfaces.

The locking channel structures 50 are located on the inside of the container 1 such that the first panel 53 of each first elongate component 51 lies against a respective inner surface of the left and right side walls 4, 5 parallel to the free longitudinal edges of said side walls 4, 5. Thereby, the gaps 67 of each locking channel structure 50 formed between the bent limbs 61 and respective reinforcing component 64 face the opposite locking channel structure 50 as well as the door 2.

The first planar part 60 and the limbs 61 of each locking channel structure 50 are formed of a single sheet of material, such as a metal sheet. In these embodiments, the thickness of the sheet of material is 6 millimetres which provides strength to the second elongate component however still allows for the component to be bent in small sections such as the bends of the extending limbs 61 using relatively inexpensive manufacturing tools. The sheet of material of the first elongate component 51 is 3 millimetres in thickness, which allows for the sheet of material to be easily bent along a greater length in comparison to a metal sheet of greater thickness.

As explained above, the first and second panels 53, 54 form the channels 66 together with the limbs 61 and respective reinforcing component 64, and the tabs 57b and 57c of the limbs 61 and the respective reinforcing component 64 secure the locking channels to the container by the tabs being welded to the side wall 4, 5. The first panel 53 provides additional strength to the first elongate component 51, however it should be understood that it is not essential so as to form a locking channel as the free longitudinal edge of the second panel can be directly secured to either side wall 4, 5 of the container 1 such that the relevant side wall 4, 5 forms a channel together with the second panel 54 and the bent limbs 61 and respective reinforcing component 34. The second panel 54 of the first elongate component 51 engages with the locking pins 28 such that as the door is in a locked position it is prevented from falling inwards to the centre of the container 1. The second panel 54 extends between a relevant side wall 4, 5 of the container 1 or the first panel 53 and the third panel 55 of the second elongate component 52. The second panel 54 therefore provides strength to the container in that it resists forces generated from an explosion within the container in a direction perpendicular to the planes of the side walls 4, 5. The third panel 55 attached to the first planar part 60 of the second component 52 counteracts forces acting perpendicular to the plane of the door 2 from inside of the container l. When the door is in a locked position, the locking pins 28 being located in the channels 66 add additional structural integrity to the locking channels as they prevent the channels from collapsing . The better the fit of the locking pins 28 in the channels 66, the greater the contribution made by the locking pins against collapse of the channels 66 in the event of forces originating from within the container 1.

The fourth panel 56 provides additional strength and structural integrity to the locking channel structures 50 as the tabs 57a of the fourth panel secures the locking channel structures 50 to the side walls of the container 1 in addition to the tabs 57b, 57c of the limbs 61 and respective reinforcing component 64. The fourth panel 56 and the securing of the panel to the walls 4, 5 serves to resist movement of the second elongate component 52 in the presence of blast forces.

It should be understood to a person skilled in the art that the number of limbs 61 forming the channels 66 and the corresponding locking hooks 28 is not restricted to the amount described above. The container of the present invention may be configured to have more or fewer channels 66 and locking hooks 28.

Operation of the container 1 will now be described with reference to the Figures. The container 1 is useable as a refuse bin. The container is secured to the ground upon which it stands by fastening means extending through holes in the base 6 and secured to the ground. When the container 1 is used as a bin, the door 2 is closed in that the looking hooks 28 of the locking plates 25, 26 are located in the channels 66 of the locking channel structures 50. The door 2 is thereby secured to the container 1 as the locking hooks 28 engage with the locking channel structures 50 restricting any movement of the door relative to the container 1. In particular, as the locking hooks 28 of each locking plate 25, 26 face opposite directions the door is restricted from moving in a bilateral direction parallel to the longitudinal axis of the container 1. The door 2 is unlocked by inserting a key 81 into a hole 80 located

approximately in the centre of the door 2 and then into corresponding hole(s) (not shown) formed in the pinion 32. By turning the key, the pinion 32 is rotated by the user and the racks 30 move in opposite directions such that the locking plates 25, 26 are moved in a direction parallel to the longitudinal axis of the container towards one another, in other terms towards the centre of the door 2. As the locking plates 25, 26 move towards the centre of the door, the locking hooks 28 move out of the channels 66 such that they locate in the gaps 67 between the limbs 61 of the locking channel structures 50. Once the key 81 is turned such that the door 2 is in an opened position, the key 81 is retained in the door and cannot be removed until the key 81 is rotated back to its original position.

To lock the door 2, the key is turned in the opposite direction thereby also rotating the pinion 32 in the opposite direction compared to when unlocking the door. By doing so the racks 30 are moved such that the locking plates 25, 26 travel away from one another and away from the centre of the door. The locking hooks 28 thereby enter the channels 66 of the locking channel structures 50. The hooks 28 are self-guided into the channels 66 as a result of the features of the reinforcing members 34 of each locking plate 25, 26 extending over the tips of the locking hooks 28 and the corners 35 of the locking hooks 28 being tapered. When the door is in its locked position, the key 81 is aligned with the hole 80 in the door such that the key 81 can be removed.

The container 1 absorbs and upwardly directs forces of an explosion originating inside the container lby the container being structurally sound and strong due to the two side walls 4, 5 and the rear wall 3 being integrally formed and the door 2 being securely attached to the container 1. In the event of an explosion within the container, forces are exerted outwards on the three walls 3, 4, 5 and the door 2 of the container. The container 1 remains in its position as it is secured to the ground upon which it stands. The three walls 3, 4, 5 can withstand forces of great magnitude as they are formed out of a single sheet of metal. The door 2, being in a locked position, remains secured to the container 1 due the locking hooks 28 of each locking plate 25, 26 facing opposite directions such that the door is restricted to move in a bilateral direction parallel to the longitudinal axis of the container. Furthermore, the fact that the locking hooks 28 and the locking plates lie in a plane perpendicular to the left and right side walls 4, 5, means that the locking hooks and the locking plates resist forces exerted in a general perpendicular direction on the inner surfaces of the side walls 4, 5, thereby retaining the side walls 4, 5 in their position. Although embodiments of the invention have been shown and described, it will be appreciated by those skilled in the art that variations may be made to the above exemplary embodiments that lie within the scope of the invention, as defined by the following claims.

Claims

1. A blast-resistant structure comprising:

a body in which is defined an aperture, the aperture being bounded by two edge parts of the body;

a door configured selectively to close-off the aperture; and

first and second securing mechanisms configured selectively to secure the door to respective ones of the body edge parts, each securing mechanism comprising a locking channel associated with the body and a corresponding locking pin associated with the door, each locking pin being moveable between an open position in which the locking pin is external to the locking channel and a secured position in which the locking pin is engaged in the locking channel,

wherein the locking channel has a generally rectangular cross-section that is defined on at least first and second sides by a locking pin retention part, and wherein the locking pin retention parts and the locking pins are formed of sheet material.

2. A structure as claimed in claim l, wherein the first and second locking pins are integrated onto a locking pin mechanism such that the first and second locking pins are in a fixed relationship with respect to one another.

3. A structure as claimed in claim 2, wherein a first single sheet of material constitutes part of both the first and second locking pins.

4. A structure as claimed in claim 3, wherein the locking mechanism includes at least two layers of sheet material at the locking pins.

5. A structure as claimed in claim 3, wherein the locking pin

mechanism comprises two pairs each of first and second locking pins, and wherein the first sheet of material and a second sheet of material constitutes both of the first locking pins and the first sheet of material and a third single sheet of material constitutes both of the second locking pins.

6. A structure as claimed in any preceding claim, comprising, for each locking pin, a reinforcing component that is formed of sheet material, the reinforcing component being secured against a first face of the locking pin with a plane of the sheet material of the reinforcing component being generally perpendicular to the first face of the locking pin.

7. A structure as claimed in claim 6 when dependent on claim 2, wherein each reinforcing component includes a bend between a part at which it is secured against the respective locking pin and a part at which it is secured against a part of the locking pin mechanism part that connects the locking pin to another locking pin.

8. A structure as claimed in claim 7 when dependent on claim 4, wherein each reinforcing component includes a step profile along one edge and wherein the reinforcing component is secured against the first sheet of material on one side of the step and is secured against another one of the sheets of material on the other side of the step.

9. A structure as claimed in any preceding claim, wherein the locking channel is defined also on a third side by the locking pin retention part.

10. A structure as claimed in claim 9, wherein the locking channel is defined also on a fourth side by the locking pin retention part.