US20140151254A1

US20140151254A1 - Cargo Holding Device in Particular for Loading Aircraft, and Method for the Production of a Cargo Holding Device

Info

Publication number: US20140151254A1
Application number: US14/123,529
Authority: US
Inventors: Thomas Huber
Original assignee: Telair International GmbH
Current assignee: Telair International GmbH
Priority date: 2011-06-07
Filing date: 2012-06-06
Publication date: 2014-06-05
Also published as: TW201311525A; WO2012168305A1; US20140131371A1; US8973769B2; TW201313580A; WO2012168314A1

Abstract

The invention concerns a freight receiver device, in particular freight container or pallet, in particular for loading aircraft, comprising at least one floor element and at least one profile element connected with the floor element, characterised in that at least one edge segment of the floor element is detachably connected with the at least one profile element via a connecting device comprising at least one hook.

Description

RELATED APPLICATIONS

This patent application is a U.S. nationalization under 35 U.S.C. §371 of International Application No. PCT/EP2012/060724, filed Jun. 6, 2012, which claims priority to German Patent Application No. 10 2011 050 893.7, filed Jun. 7, 2011 and PCT Application No. PCT/EP2011/003114, filed Jun. 24, 2011.

BACKGROUND AND SUMMARY

The present invention concerns a freight receiver device such as a container, pallet or similar, in particular for loading aircraft, and a method for production of a freight receiver device.
For effective transport of loads in aircraft, freight containers and freight pallets—i.e. freight receiver devices—are essential as they allow rapid loading and unloading of the aircraft. The great majority of commercial aircraft can receive a multiplicity of freight containers or freight pallets. Most containers or pallets are standardised so they can be used irrespective of the aircraft used for their transport. Until ten years ago freight containers were made exclusively of aluminium, wherein the own weight of the container was around 100 kg. Some containers used at present comprise lighter materials so that now, freight containers with a weight of around 60 kg are used. It should be clear that reducing the own weight of the containers or pallets used brings substantial financial and ecological advantages. A freight container is described for example in DE 20 64 241. The use of non-metallic materials (see DE 696 16 182 T2) in this context has also been considered. DE 696 16 182 T2 proposes for example a freight container which has a frame of an aluminium alloy in which side walls and a roof of fibre-reinforced plastic are used. The side walls and the roof are made as fabric webs of fibre-reinforced plastic. A frame of carbon fibre-reinforced plastic material is mentioned in said publication as a possible alternative to aluminium alloy. A technical design of such a freight container is not however disclosed in DE 696 16 182 T2. Starting from said woven or knitted fabric, the frame can be produced by lamination or in the winding process.
In DE 696 16 182 T2, the floor plate is glued into the frame and fixed by rivets. This fixing has however been found to be comparatively complex.
WO 2010/045572 A1 proposes a press seat for fixing freight container panels, which seat can be reinforced by adhesive and mechanical connecting rivets. Alternatively it is also proposed to achieve locking with a multiplicity of locking teeth. These measures are also found to be costly. A permanent connection by bonding, riveting or the use of locking teeth also makes dismantling of the freight container considerably more difficult.
Starting from said prior art, the object of the present invention is to provide an improved freight receiver device. In particular the own weight, production costs and production complexity of the freight receiver devices should be reduced and the functionality (e.g. ease of handling, security) and stability increased. This object is achieved by a freight receiver device according to claim 1. In particular the object is achieved by a freight receiver device e.g. a freight container or pallet, in particular for loading aircraft, comprising at least one floor element and at least one profile element connected with the floor element, wherein at least one edge segment of the floor element is detachably connected with the at least one profile element via a connecting device comprising a hook.
An essential concept of the invention is that the floor element can be suspended in the profile element by the provision of a hook. The result is a constructionally simple but secure connection. Assembly and disassembly of the freight receiver device are facilitated. In particular no irreversible bonding or locking is required.
Preferably a connection between the floor element and profile element can be created via a push-fit (of the floor and/or profile element) with subsequent rotation (of the floor and/or profile element in relation to each other). Alternatively or additionally, the connection between the floor and profile element can be released via a rotation (of the floor and profile element in relation to each other) with subsequent separation of the floor and profile element. In total this achieves a reliable connection which in particular facilitates assembly and disassembly. Also without providing an irreversible bonding or locking, the connection is comparatively reliable (in particular because of the provision of the hook).
In a concrete embodiment the connecting device comprises at least one groove and at least one spring. The groove can for example be provided in the profile element (and/or in the floor element). The spring is preferably provided in the floor element. Alternatively or additionally at least one groove is provided in the profile element. An extremely simple assembly and disassembly can be achieved with such a groove-spring connection together with the hook.
A cross section of the groove and/or spring can be round, in particular circular, at least in segments. As a result the profile and floor element can be rotated in relation to each other particularly easily, which facilitates assembly/disassembly. A cross section of the groove is preferably completely circular (apart from a groove opening).
At least one spring and/or at least one groove can be asymmetric so that the spring can be introduced into the groove at a predetermined first relative angle thereto and is hooked with the groove at a predetermined second relative angle (different from the first). In this embodiment the spring and groove are formed such that the spring is formed as a hook or acts as a hook in the allocated groove. This refinement is particularly simple in relation to the construction and allows a stable connection.
In particular if a cross section of the groove is circular (apart from a groove opening), a cross section of the spring can have a length (maximum length) in a longitudinal direction and a width (maximum width) in a width direction, wherein the longitudinal direction stands perpendicular to the width direction, wherein the length is greater than the width (for example at least 1.1 times or at least 1.3 times or at least 1.6 times as large). With such a linear spring (in cross section) the connection with the groove can be made simply and securely.
Preferably a cross section of the spring has an arcuate segment and opposite the arcuate segment a rotating-supporting protrusion (fulcrum). With such an embodiment the spring can be levered into the groove particularly easily by rotation, allowing assembly and disassembly.
Preferably an edge segment of the floor plate and/or at least one profile element end segment facing the edge segment of the floor plate is hook-shaped (in cross section). With the corresponding design of the edge, no separate component (for example a separate hook) is required. The connection can thus be extremely simple constructionally.
At least one floor plate edge segment of the floor plate can be curved inwards. Alternatively or additionally at least one profile element edge segment facing the floor plate edge segment can be chamfered downwards in the direction of the floor plate. In one embodiment of the freight receiver device as a pallet, “inwards” can mean that the bend is oriented in the direction of a freight receiving surface. For a container, “inwards” can mean that the bend is oriented in the direction of the centre of the freight receiving chamber. In any case, this allows a stable and in particular form fit design of the base. The material usage is extremely low. The connection between the floor element and the profile element is nonetheless reliable and secure.
The floor plate and/or at least one preferably pultruded profile element can be produced at least in segments of fibre-reinforced carbon. This firstly saves weight. In particular with production by pultrusion, the benefit arises that because of the alignment of the fibres of the profile element along its longitudinal axis, the hook construction is extremely stable against a tensile load from the floor element.
The object cited above is furthermore achieved by a freight receiver device, in particular of the type described, for example a freight container or a pallet, in particular for loading aircraft, comprising a floor plate wherein one edge of the floor plate is connected with a multiplicity of profile elements, wherein the profile elements are connected together via a multiplicity of push-fit connections, wherein two adjacent profile elements only at their ends facing away from the respective other profile element each form a push-fit connection with a third profile element (in the sense of a “further” element).
A core concept of this freight receiver device is that by connecting together a multiplicity of profile elements, in a simple manner a frame can be formed in which the floor element can be held. By the omission of a push-fit connection on two adjacent profile elements, the frame can be closed particularly simply by form fit. In particular in combination with a hook construction as described above, the floor plate can be connected simply and reliably with the profile elements. In total a constructionally simple assembly or disassembly is achieved.
Preferably several corner elements are provided which are each connected with two profile elements via push-fit connection, wherein an end corner element is provided which is connected with maximum one profile element via a push-fit connection. Via assembly of the freight receiver device, in a particularly simple manner a frame can be constructed comprising the profile elements and corner elements, wherein because of the particular design of the end corner element, the frame can be closed by form fit in a simple manner (without needing to deform the frame). Thus the frame can be produced very simply. In a concrete embodiment several corner elements are provided with two push-fit connecting pins, each of which can be introduced into one profile element, wherein an end corner element is provided which comprises maximum one push-fit connecting pin.
In a concrete refinement, at least one wall element and at least one profile element are fitted with a slot, wherein a preferably peripheral and in particular widened edge of the wall element is or can be inserted in the slot. With such a design, tensile loads at right angles to the edge of the wall (tarpaulin edge) can be transmitted within a tarpaulin layer. Thus in combination with the construction and assembly of the floor element, synergistically a simple yet stable construction of the entire freight receiver device is achieved. The wall element is used in a simple manner as a structural element for the entire freight receiver device. This allows an even lighter frame construction and the omission of separate connecting means such as rivets and screws.
Preferably at least one wall element is provided which has a bracing running from one wall corner to the diagonally opposing wall corner, in particular comprising an additional wall layer (tarpaulin layer). Further preferably, bracings run from all four wall corners to the diagonally opposing wall corners so that in total a cross-shaped bracing is formed. The at least one bracing can be achieved by a (local) increase in the number of layers (tarpaulin layers). The bracings allow tensile loads to be absorbed via corner points so that these need not (any longer) be dissipated via the frame profile. In particular in combination with the floor element described above, a construction is achieved which is extremely light and simple to install. Any push-fit connections or hook connections provided are stabilised by the bracings. With this measure the at least one wall element becomes a structurally reinforcing element of the entire freight receiver device. This allows lightweight construction (frame construction) and the omission of connecting means such as rivets or screws.
The object cited above is furthermore achieved by a method for production of a freight receiver device, in particular the type described above, comprising at least one floor element and at least one profile element connected with the floor element, wherein the floor element and profile element are guided to each other at a first predetermined angle and then hooked together by rotation. In relation to the benefits of the method, reference is made to the freight receiver device described above.
According to an independent concept, a method is proposed, preferably of the type described above, for production of a freight receiver device, in particular of the type described above, comprising at least one floor element and a multiplicity of profile elements connected with an edge of the floor element, wherein several profile elements are connected together with two adjacent profile elements via a push-fit connection, wherein two adjacent end profile elements only at their ends facing away from each other are each connected with a third profile element (in the sense of a “further” element) via a push-fit connection.
According to a refinement which is claimed independently, the object is also achieved by a freight receiver device such as a container, pallet or similar, in particular for loading aircraft, wherein the freight receiver device comprises at least one floor element and at least one pultruded profile element of fibre-reinforced plastic.
One essential concept of this refinement or independent aspect is that to stabilise the freight receiver device, a profile element of fibre-reinforced plastic is used which is produced in the pultrusion process (extrusion drawing process). Because of the pultrusion process, the profile element of fibre-reinforced plastic has a resistance in particular to a bending load which cannot be achieved by conventional methods for processing fibre-reinforced plastic (for the same material usage). In total therefore a stable construction of a freight receiver device is possible with less material usage. As a result the weight of a freight receiver device can be further reduced substantially. Furthermore an efficient production is ensured.
Preferably at least one profile element is formed at least in segments as a hollow profile. As a result a further weight reduction can be achieved with the same or increased stability.
At least one profile element can form at least one part of a frame of the freight receiver device, in particular the floor element. Forces which act on the frame of such a freight receiver device can be distributed to the frame particularly favourably by the pultruded design of the profile element.
At least one profile element can comprise at least one fixing device, such as for example a push-fit device, in particular a preferably rounded groove or rail for fixing a wall element, in particular a floor element and/or a lashing device. In particular a groove or rail can be produced with little cost during the pultrusion process. Thus a weight-saving possibility is found for connecting different wall elements to the profile element in a simple manner. In particular when the profile element is formed as part of a frame, the freight receiver device can be assembled, dismantled and repaired in a simple manner.
In concrete embodiments the profile element can be connected with a further profile element and/or a corner element via a push-fit connection. In particular the push-fit connection between two profile elements can be achieved via a corner element. The push-fit connection between two profile elements can however also take place directly in that the profile elements are in contact. Two or more profile elements can also be assembled into an extended profile element via one or more (straight) intermediate pieces. Thus in a simple manner different profile elements can be created or a size adjustment to the freight receiver device made in a simple manner.
In a preferred embodiment at least one corner element is provided for connection, in particular push-fit connection, of two profile elements. The at least one corner element can have at least one pin (extension) corresponding with a recess of the profile element. In the design of the profile element as a hollow profile, the pin (extension) in its cross section preferably corresponds to the cross section of the cavity of the hollow profile. This too facilitates production of the freight receiver device.
Preferably at least one (where applicable tarpaulin-like) wall, in particular a side wall or cover, is made at least in segments from a fibre-reinforced plastic. In connection with the pultruded profile element, in total an extremely light freight receiver device with high stability can be achieved.
At least one wall, in particular a base wall or a freight floor, can have a core layer of fibre-reinforced plastic and a seating layer (support layer) of a metal, in particular an aluminium alloy, wherein the core layer and seating layer are connected together preferably by material connection. An essential concept of this embodiment is to reduce the weight for example of the compartment floor in that this is made of several layers, in particular in a sandwich construction, wherein metal and plastic materials are used for the layers. The base wall can be constructed as explained in German patent application with file ref: DE 10 2011 050 893.7 and/or produced accordingly. Metal and plastic materials can be used for the layers. Predefined requirements e.g. with regard to friction and wear behaviour can be taken into account here, wherein a very stable composite material or laminate material is produced.
Preferably the layers are connected by material and/or form fit, wherein a material connection leads to particularly good results.
Preferably the seating layer of a metal alloy serves as the outer layer on which the freight drive units act. Furthermore this layer bears spot loads and distributes them over a broad area. An aluminium alloy is particularly suitable here as it gives very good coefficient of friction in conjunction with conventional rollers of freight drive units. The core layer which directly follows the seating layer reinforces the entire construction and leads to substantial weight savings.
The seating layer can have a thickness of 0.5 mm to 2.5 mm, in particular 0.7 mm to 1.5 mm, in particular 0.9 mm to 1.5 mm. Preferably in relation to the thickness of the entire freight floor, the seating layer only has a small thickness e.g. less than 40%, in particular less than 30%, in particular less than 20% of the total thickness. To this extent significantly lighter freight floors can be produced.
The seating layer can have a strength of more than 400 N/mm², in particular more than 500 N/mm². To this extent the seating layer protects the core layer from high spot loads. The freight floor according to the invention is exposed to only very low wear under conventional rough treatment, and is very robust.
It is possible to design the freight floor in multilayer structure only as two layers. Preferably however a further layer, namely a wear layer or cover layer, can be provided which is arranged on the side of the core layer facing away from the seating layer.
The wear layer can be made of a metal alloy, in particular an aluminium alloy, and/or a glass fibre-reinforced plastic and/or a material from the group of aromatic polyamides (e.g. aramide). The wear layer can protect the core layer from wear and reinforce the sandwich construction as a whole.
Said aluminium alloys for the seating layer and/or the wear layer can be aluminium wrought alloys. The main alloy element used can be zinc, wherein zinc accounts for a proportion of 0.7 to 13%, in particular 0.8 to 12%. Such aluminium alloys are very hard. For example material 7075 T6 or 7075 T7 can be used.
Preferably the wearing layer is connected with the core layer by form fit and/or material fit.
Said aluminium alloys can be aluminium alloys which have been solution-treated and/or heat treated and/or overhardened so that sufficient strength is achieved.
The core layer can have a thickness of at least 1 mm, in particular 1.5 mm, in particular at least 2 mm, in particular at least 4 mm, in particular at least 6 mm.
Preferably the core layer is a solid core. According to the application a solid core is a core which is substantially solid. This means that the core layer is constructed to at least 50%, in particular at least 70%, in particular at least 90% of carbon fibre-reinforced and/or glass fibre-reinforced plastic. Greater cohesive voids, in particular honeycombs or similar, are not provided.
The wear layer can have a thickness of 0.1 to 1 mm, in particular 0.2 to 0.6 mm, in particular 0.25 to 0.5 mm.
Preferably at least one wall has, at least in segments, an in particular rounded bead on its edge to fix the wall to at least one profile element. As a result particularly simply a connection can be achieved to the profile element or one of the profile elements in that for example the bead is introduced into a (rounded) groove of the profile element.
At least one wall, in particular the base wall, can be curved inwards on at least one edge region. When the freight receiver device is designed as a pallet, “inwards” can mean that the bend is oriented in the direction of the freight receiving surface. For a container, “inwards” can mean that the bend is oriented in the direction of the middle of the freight receiving chamber. In each case (in particular in conjunction with a rounded bead on the edge of a wall), this achieves a stable and in particular form-fit construction of the wall, in particular the floor. The material usage is extremely low.
At least one wall can comprise at least two layers of fibre-reinforced plastic, wherein a ply angle of a first layer in relation to the ply angle of the second layer is offset by at least 30° and/or maximum 90°, in particular by 45° or 90°.
At least one wall can comprise at least one first layer with (exclusively) 0°/90° ply and at least one second layer arranged on the first layer with (exclusively) −45°/+45° ply. Reference is made to a predetermined longitudinal edge of the freight receiver device. With the two layers in a simple manner both stabilisation in a corner region (by the −45°/+45° ply) and stable fixing to the profile elements running for example at the edge (by the 0°/90° ply) can be achieved.
At least one wall can at least in segments be made of glass fibre-reinforced plastic and/or carbon fibre-reinforced plastic and/or aramide and/or kevlar.
Preferably aramide/kevlar is used in particular to improve handling for example with forklift trucks. Alternatively on the outside of the freight receiver device, a film could be drawn over (conventional) freight receiver walls or pallets. A thin outer layer (in production of the walls) can be introduced (for example as a further layer). In a refinement, the freight receiver device/pallet can be designed to reflect sunlight (without a protective sleeve needing to be provided). A sunlight-reflecting layer can be used instead of a protective envelope. This is advantageous insofar as protective envelopes in the prior art can often only be used once as they are damaged after first use (e.g. holes are created etc.).
At least one edge bead can be formed by a rod integrated into the edge, in particular made of fibre-reinforced plastic such as glass fibre-reinforced plastic or carbon fibre-reinforced plastic. Thus in a simple manner a connection with a fixing device of a profile element can be achieved.
Preferably at least one wall is attached via at least one corner plate to a/the frame of the freight receiver device, wherein the corner plate preferably comprises at least one bore, in particular partly lined with the wall. Further preferably at least one in particular tarpaulin-like wall is attached via at least one plate to a frame of the freight receiver device, wherein the plate preferably has a bore, wherein further preferably at least one layer of the particularly tarpaulin-like wall is pressed into the bore. Thus with a suitable fixing means with preferably cylindrical cross section, for example a bolt, in a simple manner a secure fixing of the in particular tarpaulin-like wall can be achieved. For this it is furthermore advantageous if the fixing means has a flange segment. The in particular tarpaulin-like wall can be clamped between this flange segment and a profile element to further improve stability.
The plate at least in regions can be arranged inside the wall and preferably tapered in the direction of the wall centre. This gives a comparatively homogenous transition region from the plate to the in particular tarpaulin-like wall (in the region in which this is not connected with the plate). This further improves the stability of the fixing. The weight is reduced.
The object cited above is achieved according to a refinement of the method described above (which also has an independent aspect and is claimed as such) by a method for production of a freight receiver device in particular of the type described above, comprising at least one profile element, wherein the profile element at least in segments is made by pultrusion of fibre-reinforced plastic. With reference to the benefits, reference is made to the freight receiver device already described. A central advantage of this method is the possibility of producing freight receiver devices with substantially reduced own weight.
At least one wall of the freight receiver device can be made of an in particular tarpaulin-like fibre-reinforced plastic wherein segments of the wall can be pressed into a bore of a fixing plate, preferably by use of a tool with conical segment. Thus the fixing of the wall of fibre-reinforced plastic to the profile element can be achieved particularly securely.
Preferably the production method comprises production of a groove on the at least one profile element, preferably by pultrusion, and connection of the at least one wall with the at least one profile element by introduction of a bead-like segment of the wall into the groove.
In a preferred embodiment the production method comprises a push-fit connection of a multiplicity of profile elements to produce a frame, in particular using corner elements.
Preferably the frame is braced by the fitting of a/the wall on the frame.
The object cited above is furthermore achieved independently by the use of a pultruded profile element of fibre-reinforced plastic for the production of a freight receiver device, in particular of the type described above.
The present freight receiver device can completely omit metal components. In a concrete embodiment the freight receiver device can comprise an electromagnetic transmitter and/or receiver, in particular an RFID chip. By the omission of metal components or at least a reduction in the proportion of metal components, this electromagnetic receiver and/or transmitter device can communicate particularly easily with the corresponding external transmitter or receiver. Interference from metal components is avoided or at least reduced.
By the special construction of the freight receiver device, as a whole the weight is again reduced significantly in relation to known freight receiver devices. A weight reduction of 35% or more appears possible, which for example in a Boeing 747 could be around 640 kg per total load weight in relation to loading with known containers. If it is assumed that a Boeing 747 with maximum load consists of around one-third aircraft, one-third passengers or freight and one-third fuel, and in this form has a take-off weight of around 408 tonnes, we reach the result that around 130 tonnes fuel are required to transport 272 tonnes of aircraft and load. With the freight receiver device according to the invention in such a case around 320 kg fuel could be saved per flight. Thus the CO₂emission in turn could be reduced significantly.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is now described below by means of several embodiment examples explained in more detail in the attached drawings.

These show:

FIG. 1 a diagrammatic depiction of a freight container in oblique view;

FIG. 2 the freight container of FIG. 1 in a view from above;

FIG. 3 the freight container in a view cut along line of FIG. 2;

FIG. 4 a pultruded profile element in an oblique view;

FIG. 5 the pultruded profile element according to FIG. 4 in a side view;

FIG. 6 a section along line VI-VI of FIG. 5;

FIG. 7 a corner element in a first oblique view;

FIG. 8 the corner element of FIG. 7 in a second oblique view;

FIG. 9 a second embodiment of a pultruded profile element in a diagrammatic section view;

FIG. 10 a second embodiment of a corner element in a diagrammatic oblique view;

FIG. 11 the corner element according to FIG. 10 in side view;

FIG. 12 an extract of the pultruded profile element according to the first embodiment and an extract of a floor element in a diagrammatic section view according to a first embodiment;

FIG. 13 components of a wall and a mould for production of a edge bead in a diagrammatic section view;

FIG. 14 an extract of an edge of a wall of a freight receiver device in diagrammatic section view;

FIG. 15 a fixing of a wall of the freight receiver device to a corner element in a view from above;

FIG. 16 a partial section along line XVI-XVI from FIG. 15;

FIG. 17 an alternative possible embodiment of a region of the fixing of the wall to the corner element in a diagrammatic section;

FIG. 18 a side corner element with extracts of two side walls and a cover;

FIG. 19 a diagrammatic section view of an extract of a profile element and an extract of a floor element in diagrammatic side view according to a second embodiment in a first relative position;

FIG. 20 the profile element and floor element of FIG. 19 in a second relative position;

FIG. 21 the profile element and floor element according to FIG. 19 in a third relative position;

FIG. 22 an oblique view of an alternative embodiment of a corner element; and

FIG. 23 a further alternative of an embodiment of a corner element in oblique view.

DESCRIPTION

In the description below, the same parts and those with the same effect carry the same reference numerals.
FIG. 1 shows a freight container 10 in an oblique view. FIG. 2 shows a freight container in a view from above. The freight container 10 comprises a frame 11 and side walls 12 a to 12 d (attached to the frame), a cover 13 and a floor 14. The side wall 12 c then runs obliquely outwards at the floor 14 (at a 45° angle). As well as this oblique segment 14, the side wall 12 c comprises a vertical segment 16 which extends to the cover 13. The other side walls 12 a, 12 b and 12 d run perpendicular throughout in relation to the floor 14 and the cover 13.
The frame 11 comprises first profile elements 17 and second profile elements 18, wherein the first profile elements 17 and the second profile elements 18 differ in particular in their cross section. The first profile elements 17 are part of a floor frame 19. The second profile elements 18 are part of a side frame and a cover frame 21.
In the floor frame 19 are integrated floor corner elements 22. Two first profile elements 17 and a second profile element 18 can be pushed onto the floor corner elements 22. The side frame 20 and cover frame 21 comprise side corner elements 23 at which three second profile elements 18 can be pushed on (connected).
FIG. 3 shows a section along line in FIG. 2. It is clear that between the oblique segment 15 and vertical segment 16 of the side wall 12 c is arranged a second profile element 18. It is furthermore evident that the first profile element and second profile element are formed as hollow profiles, wherein a cavity 24 is of the first profile element 17 and a cavity 25 of the second profile element 18 are formed differently.
FIG. 4 shows a profile element in an oblique view. FIG. 5 shows the profile element in a view from the side. FIG. 6 shows a section along line VI-VI in FIG. 5. As can be seen from FIGS. 4 and 6, the first profile element 17 comprises a floor receiving groove 26 to receive or fix the floor 14, and a side wall receiving groove 27 to receive or fix one of the side walls 12 a to 12 d, and a seat rail construction 28 for insertion (hooking) of the lashing eyes for the load.
In concrete terms the floor 14 or a floor plate can be pushed into the floor receiving groove 26. Because of the provision of the floor receiving groove, in general no additional connecting parts such as for example rivets are required. Thus the construction and complexity of assembly are substantially simplified.
Also side walls 12 a to 12 d can be inserted in the side wall receiving groove 27. The floor receiving groove 26 and/or side wall receiving groove 27 preferably has a round cross section and is suitable for receiving a round bead (see below) of the floor 14 or one of the side walls 12 a to 12 d or the cover 13.
The seat rail construction 28 has a linear cross section with inwardly curved hooks 29 to retain lashing eyes.
The cavity 24 of the first profile element (see FIG. 6) has an (approximately) rectangular cross section, wherein a wall adjacent to the floor 14 (not shown in FIG. 6) is bent outwards. In particular the inner contour of the profile element 17, 18 can vary; an outer contour can also vary, where applicable taking into account the freight system. The inner cross sections can in particular be adapted to different loads. The outer contour can be adapted to the interface to the freight system, for example edge corners can be formed to receive locks and guides.
The floor corner elements 22 can be extended and/or widened (in the vertical direction) with a flange plate (not shown in the figures), in particular to connect the first profile elements with the floor corner element 22 using bolts. The floor corner elements 22 (where applicable also the side corner elements 23) can be formed of a composite material (in particular fibre composite material) or where applicable also of aluminium alloy (cast or forged). When the corner elements comprise a metal alloy, corrosion protection can be provided between the pultruded profile elements and the corner elements (since for example carbon fibre-reinforced plastic is comparatively aggressive against aluminium).
The seat rail construction 28 can comprise bores (not shown in the figures) (wherein the bores can be machined subsequently and have a diameter of 19 mm) to attach or hook lashing eyes (single tie-down and double tie-down studs), for example when heavy loads are flown in the freight container which also need to be lashed within the container 10. In the case of pallets, these can also run peripherally on the inside, for example to attach pallet nets to the pallets. Previously normally aluminium pieces were screwed on or riveted in for this. This seat rail construction 28 is integrated in the present profile element and also where applicable made of pultruded fibre composite plastic (e.g. carbon fibre-reinforced plastic or glass fibre-reinforced plastic etc.).
FIGS. 7 and 8 show one of the floor corner elements 22 in various oblique views. The floor corner element 22 is adapted to connect (by push-fit) with two first profile elements 17. For this two cavity receiving pins 30 are formed, onto each of which a cavity 24 of the first profile element can be pushed (not shown in FIGS. 7 and 8; see FIG. 6). To this extent an outer contour of the cavity receiving pin 30 corresponds to an inner contour of the cavities 24 of the first profile element 17. Furthermore seat rail receiver pins 31 are provided which are adapted to be introduced into the seat rail construction 28 of the first profile element 17. To this extent preferably an outer contour of the seat rail receiving pin 31 corresponds to an inner contour of the seat rail construction 28. Thus the seat rail construction 28 allows not only the lashing (fixing) of the object to be transported, but furthermore contributes to stabilising the freight container 10. As a result further material can be saved which reduces the overall weight. According to an independent concept, a freight receiver device is proposed in which at least one connecting element for connecting two profile elements comprises at least one seat rail receiving pin which can be introduced into a seat rail construction of a (pultruded) profile element.
The floor element 22 comprises a side wall web 32 which extends in the direction of the side walls 12 a to 12 d (not shown in FIGS. 6 and 7). At a distal end 33 of the side wall web 32 is provided a (horizontal) segment with curving groove 34 to attach the side walls 12 a to 12 d to the first profile element 17. The curving groove 34 in the assembled state (see FIG. 1) transforms into the side wall receiving grooves 27 of the first profile element 17.
FIG. 9 shows the cross section of the second profile element 18 which is preferably used on all edges of the container (except the edges towards the floor 14). The side walls 12 a to 12 d and the cover 13 can be connected preferably by push-fit (via joint closure) with the second profile elements. Here too no costly connection process is required, such as for example riveting.
The second profile element according to FIG. 9 comprises a first side wall receiving groove 27 a and a second side wall receiving groove 27 b to connect the two side walls 12 a to 12 d or one of the side walls 12 a to 12 d with the cover 13. The side wall receiving grooves 27 a and 27 b also have an (approximately) round or roundish cross section and are adapted to receive a bead of the side walls 12 a to 12 d or cover 13. The cavity 25 of the second profile element 18 is formed (approximately) in the manner of a circle segment, and in the region of an arc has a recess 35. Also the cross section of the second profile element depends in particular on the loads to be received, which can vary. To this extent the cross section of the cavity 25 or second profile element 28 can also differ (from the form shown in FIG. 9).
FIG. 10 shows a side corner element 23 in an oblique view. FIG. 11 shows the side corner element according to FIG. 10 in a side view. The side corner element 23 comprises three cavity receiving pins 36 which can be introduced in the corresponding cavities 25 of three second profile elements 18. Where applicable corner regions of the side walls 12 a to 12 d or the cover 13 can be introduced into the curving grooves 37. A further possibility of creating a corner connection is explained below. As a whole, the side corner element 23 is formed as a three-legged angle bracket.
FIG. 12 shows an extract of a floor 14 (floor plate) which is introduced into a first profile element 17 (shown in extract). The floor 14 comprises a (round) edge bead 38 which is introduced into the floor receiving groove 26 of the first profile element 17. Thus in a simple manner, (horizontal) loads which can occur in operation can be absorbed.
The floor 14 comprises a first floor layer 39, a second floor layer 40 and a third floor layer 41. The first (bottom) floor layer 39 is made preferably of an aluminium alloy (in particular from the 7075 series) and can allow adequate support against transport rollers (PDU rollers). Above the first floor layer 39 can be laid a second floor layer 40 of fibre-reinforced plastic (such as carbon fibre-reinforced plastic and/or glass fibre-reinforced plastic) and/or aramide and/or kevlar. The second floor layer 40 or also a third floor layer 41 lying above the second floor layer can form a (fine) braided layer (steel braided layer) in order where applicable to achieve electromagnetic screening. In total more than three floor layers can also be provided. A combination of several of the above materials, in particular fibre materials, is conceivable. The thickness of the floor plate can be 1.5 to 4.5 mm, in particular (around) 3.2 mm. An underside metal plate (corresponding to the first floor layer 39) can have a thickness of 0.5 to 1 mm, in particular (around) 0.75 mm.
A floor edge 42 has an upward bend 43 (in the direction of the interior of the freight container). In this way a favourable (flush) transition to the first profile element 17 can be achieved. Furthermore delamination of a metal coating can be avoided when the transport rollers (PDU rollers) run over a corner edge of the floor during operation. The bend 43 runs parallel to an oblique surface 44 of the first profile element 17. As shown in FIG. 12, in particular the first floor layer 39 (metal layer) can also be provided in the region of this oblique surface 44. It is also conceivable to extend the metal layer (first floor layer 39) into the floor receiving groove 26. Such measures achieve both a stable connection and prevent delamination (largely). One or more of the floor layers can be made of fibre-reinforced plastic which contains a −45°/+45° ply and a 0°/90° ply. The reference line here is an edge of the floor 14 (i.e. in FIG. 12 a direction perpendicular to the drawing plane). The degree figures refer to a mean orientation of fibres within the fibre-reinforced plastics.
A fundamental construction of the side walls 12 a to 12 d and the cover 13 can be seen (in extract) in FIG. 14. FIG. 13 shows part of the production process to achieve the construction in FIG. 14.
Side walls 12 a to 12 d and the cover 13 can be formed as a tarpaulin (sheet) and comprise an edge bead 45 (see FIG. 14). The edge bead 45 runs at least partly about the side walls 12 a to 12 d and cover 13 and can preferably be inserted in the floor corner element 22 or second profile element 18.
The side walls 12 a to 12 d (formed as tarpaulins) and the cover 13 can be made of a carbon fibre-reinforced plastic, a glass fibre-reinforced plastic, aramide and/or kevlar. Other fibre composite materials are conceivable. In FIG. 14 (apart from a region adjacent to the edge bead 45) three layers are formed (further layers can also be provided), namely a first side wall layer 46, a second side wall layer 47 and a third side wall layer 48. Preferably the second (middle) side wall layer 47 is formed as a 0°/90° ply (in relation to a side wall edge 49 which in FIG. 14 runs perpendicular to the drawing plane) (it should be pointed out here that where the text below refers to a side wall or side wall edge or similar, this can always also mean the cover 13 or its allocated elements unless explicitly stated otherwise). The first side wall layer 46 and third side wall layer 48 are preferably formed as a −45°/+45° ply. In FIG. 15 the solid lines 67 depict for example the orientation of the −45°/+45° ply. Dotted lines 68 depict the 0°/90° ply.
The middle layer 47 is thus formed to transmit in particular (pure) tensile forces between the profile elements 17, 18. The first and third side wall layers 46, 48 are preferably formed to support corner points of the side walls 12 a to 12 d (or cover 13) or transmit tensile forces from corner to corner.
The side wall layers 46 to 48 can be 0.1 to 0.4 mm thick, in particular (around) 0.25 mm. The side walls 12 a to 12 d or cover 13 can have a total thickness of around 0.5 to 1 mm, preferably 0.75 mm. Greater thicknesses are conceivable (in particular with correspondingly high weights).
Preferably at least one of the three side wall layers 46 to 48 is made of aramide (kevlar), in particular to achieve a high cutting resistance of the side wall. Thus the security of the freight receiver device is further increased. For example, no unauthorised person (with simple means) can make a slot in the side walls 12 a to 12 d and insert a hazardous object (for example a bomb). Also the use of aramide (kevlar) means that the freight receiver device is even more stable against damage (for example on a collision with a forklift truck or similar).
In principle the side walls 12 a to 12 d and the cover 13 are formed such that (in particular via the edge bead 45) on the side wall edges 49, tensile forces can be absorbed by the first and second profile elements (which means that the pultruded profile elements cannot be pulled apart or only to a limited extent, and the structure of the frame of the freight container 10 is retained). In particular the combination of the special ply arrangement (0°/90° ply and −45/+45° ply) and the pultruded design of the profile elements allows a particularly light but stable construction.
Forming the side walls 12 a to 12 d or the cover 13 as tarpaulins has the advantage that damage such smaller holes can be repaired comparatively easily with a repair piece, which can for example be glued on.
FIG. 13 shows diagrammatically a first part of the manufacturing process for the edge bead 45. In a first step a rod 50 is provided. The rod 50 can be formed preferably of fibre-reinforced plastic (carbon fibre-reinforced or glass fibre-reinforced) and further preferably produced in a pultrusion process. The rod can for example have a diameter of 1.5 to 2.5 mm. The rod 50 is connected (preferably integrally) with lugs 51 (in particular as flat segments running along the rod). Preferably the rod 50 and the lugs 51 can be pultruded in a common pultrusion process. This considerably simplifies the production process. According to an independently claimed concept, a rod for forming the edge bead of a side wall (or cover or floor) can be pultruded with two lugs running along the rod. The lugs 51 can have an angle of (around) 45° to 60° to each other.
The rod 50 with the lugs 51 can be laid in a mould 52. In the mould 52 can already be laid further side wall layers (FIG. 13 shows the side wall layer 47). Preferably (not shown in FIG. 13) at least one side wall layer is arranged on each of an inner face 53 of a first moulding tool 54 and an inner face 55 of a second moulding tool 56. A preferred process sequence can then be as follows:

- Introduction of the first side wall layer 46 (not shown in FIG. 13) in the first moulding tool 45;
- Laying of the rod 50 with the lugs 51 between the first moulding tool 54 and the second moulding tool 56;
- Introduction of the second side wall layer 47 on the (lower) lug 51 or between the lugs 51;
- Introduction of the third side wall layer 48 (not shown in FIG. 13) between the second moulding tool 56 and the rod 50 with lugs 51;
- Closure of the mould 52 or moving together the first moulding tool 54 and second moulding tool 56;
- Optional heat application to join the side wall layers 46 to 48.

One or more of these steps can also be omitted. On closure of the mould 52, the lugs 51 are compressed and the rod 50 (load-carrying) is connected with the side wall 12 a to 12 d or a cover 13.
For example before introduction of the third side wall layer 48 (see below) a corner plate can also be introduced in a corner region.
FIGS. 15 to 18 show the mounting of the side walls 12 a to 12 d or the cover 13 to a corner region 57 (see FIG. 15) of the frame. A corner plate 59 (see FIG. 16) is introduced in a side wall cover region 58. The corner plates 59 can for example have a triangular or square contour and/or a thickness of (around) 1 to 4 mm, preferably 2 to 3 mm. The corner plates 59 can also be attached where applicable by screwing and/or riveting to the floor corner elements 22 or side corner elements 23.
The corner plates 59 let into the side walls 12 a to 12 d or the cover 13 can where applicable dissipate forces by the −45°/+45° ply such that the frame 11 of the freight container 10 cannot be shifted obliquely (as is the case for example with known supporting structures for bridges or ceilings). With different ply directions (−45°/+45° and 0°/90°), with a low use of materials and weight, an extremely strong construction can be achieved which transfers loads directly by (pure) tensile forces via the side walls or the cover to the frame 11 (and vice versa). Also replacement of a damaged side wall or cover is easily possible as no permanent connections such as rivets are required, and the side walls or cover need simply be pulled out of the profile elements in large parts (and where applicable unscrewed at the corners). The push-fit construction according to the invention of the frame 11 further facilitates such replacement.
The corner plate 59 can be either a (ready made) plastic part (where applicable comprising a fibre component) or a metal part (for example an aluminium alloy), in particular a metal stamping. Here too (in the connection of a metal, in particular aluminium, part) corrosion protection must be taken into account, in particular on the use of carbon fibre-reinforced plastic. Bores 60 (see FIG. 16) can be pre-produced in the corner plates 59. These bores 60 can have a (comparatively high) edge chamfer 61 (on one or both opposing outer faces of the corner plate 59). Preferably the corner plate tapers in the direction of a middle of the respective side wall 12 a to 12 d or cover 13, in particular to ensure the stable (flush) transition from the plate, around 2 to 3 mm thick to the tarpaulin, (around) 0.75 mm thick.
A mould for production of the joint of the respective side wall 12 a to 12 d or cover 13 with the corner plate 59 can comprise a pin with a conical segment to press material of one of the side wall layers 46-48, in particular the first side wall layer 46 and/or third side wall layer 48, into the bores 60 or their edge chamfers 61 (see FIG. 16). For this it is necessary to position the corner plate 49 as precisely as possible in the production mould. The first side wall layer 46 and third side wall layer 48 can, on closure of the mould, be pressed into a recess 62 (obliquely downwards) delimited by the edge chamfer 61. Here the fibres should not be destroyed but shaped around the bore 60.
In the extract according to FIG. 17, details are shown of a screw connection with a bolt 63 and a nut 64. Both the bolt 63 and the nut 64 have a (comparatively large) flange segment 65 (the flange segments 65 need not be provided simultaneously). As a whole the bolt 63 has an enlarged head 66 which can be adapted to the first edge chamfer 61. The first side wall layer 46 is curved inward by the production process previously described. Consequently the third side wall layer 48 is also bent inwards in the region of the allocated edge chamfer 61. In total the present construction achieves an improved and clearly defined force flow in the corner region 57.
FIG. 18 shows a diagrammatic oblique view of a side corner element 23 with an extract from a side wall 12 a, a side wall 12 b and the cover 13. The side walls 12 a, 12 b and the cover 13 are connected via corresponding corner plates 59 with the side corner element 23. The corner plates 59 have a triangular contour and are connected via several (three) bolts 63 with the side walls 12 a, 12 b and the cover 13 firstly, and with the side corner element 23 secondly. According to the diagrammatic drawing in FIG. 17, the corner plates 59 are arranged above the side walls 12 a, 12 b and the cover 13. In a preferred embodiment however the corner plates 59 are introduced into the side walls 12 a, 12 b and the cover 13 (at least in regions) (see FIGS. 15 to 17).
FIG. 19 shows extracts of a first profile element 17 and the floor element 14 according to a second embodiment (in cross section). The floor element 14 according to FIG. 19 is formed in several layers. The profile element 17 is formed like the profile element according to FIGS. 4 to 6 (with regard to shape).
The floor 14 consists of two (multiple ply) layers which are folded at the floor edge 42 to lie above each other. The floor edge 42 has an (upward projecting) edge bead 45. The edge bead 45 has a length L and a width B. Length L is greater than width B (around 1.2 times as large). The edge bead 38 (in cross section) has an arcuate segment 69 which corresponds to an arcuate segment 70 of the floor receiving groove 26 of the profile element 17. Opposite the arcuate segment 69, the cross section of the edge bead 38 has a protrusion 71 which serves to move the edge bead 38 or floor edge 42 into the floor receiving groove 26 (by rotation). A segment next to a distal end of the arcuate segment 69 is formed flat. Thus the edge bead 38 can be kept comparatively narrow so that it can be introduced into the floor receiving groove 26. This simplifies the connection of floor element and profile element. If now the edge bead 38 is moved (translationally) along an arrow 72 into the floor element receiving groove 26, the relative position of profile element and floor element results as shown in FIG. 20. If the floor element 14 and profile element 17 are now rotated in relation to each other (see FIGS. 20 and 21), the edge bead 38 hooks into the floor receiving groove 26. The edge bead 38 thus forms a hook. The rotation angle between the positions in FIG. 20 and FIG. 21 is (approximately) 40° to 70°. In the end position according to FIG. 21, the floor surfaces of profile element 17 and floor element 14 are aligned parallel to each other.
FIG. 22 shows a diagrammatic oblique view of a further embodiment of a corner element. The floor corner element 73, like the floor corner element 22 in FIGS. 7 and 8, is adapted to connect (by push-fit) with two first profile elements 17. For this two cavity receiving pins 30 are formed, onto each of which can be pushed a cavity of the first profile element 17 (see FIG. 6). An outer contour of the cavity receiving pin 30 corresponds with an inner contour of the cavity 24 of the first profile element 17. In contrast to the embodiment in FIGS. 7 and 8, in the embodiment in FIG. 22 there is no seat rail receiving pin 31 (this can also be omitted in the embodiment according to FIGS. 7 and 8 and/or provided in the embodiment according to FIG. 22). A third cavity receiving pin 74 is adapted to be connected via a push-fit connection with a second profile element 18 (see FIG. 9). For this the outer contour of the third cavity receiving pin 74 is formed corresponding to the inner contour of the cavity 25 of the second profile element 18 (see FIG. 9). The floor corner element 73 according to FIG. 22 has a multiplicity of bores 75 in which can be introduced pins (or screws or similar) in order to connect (for example diagonal) straps or other elements of the freight container with the floor corner element 73.
FIG. 23 shows a further embodiment of a floor corner element or end corner element 76. The end corner element 76 corresponds to the floor corner element 73 according to FIG. 22 with the difference that the floor corner element 76 has no cavity receiving pins 30. The cavity receiving pin 74 to receive the second profile element 18 is however provided. The floor corner element 76 thus, in contrast to the floor corner element 73 according to FIG. 22, is not suitable for production of a push-fit connection to a first profile element 17.
In a concrete embodiment of the freight container, three corner floor elements 73 according to FIG. 22 are present and one floor corner element 76 according to FIG. 23. Thus in a simple manner a peripheral frame can be produced which can be constructed entirely without bonding, screwing or similar. Adequate stability is however guaranteed (to which also the bores 75 or corresponding support elements, such as for example diagonal straps, can contribute). It is pointed out here that all the parts described above, alone or in any combination, in particular the details shown in the drawings, are claimed as essential to the invention. Derivations are common knowledge to the person skilled in the art.

LIST OF REFERENCE NUMERALS

- 10 Freight container
- 11 Frame
- 12 a to 12 d Side wall
- 13 Cover
- 14 Floor
- 15 Oblique segment
- 16 Vertical segment
- 17 First profile element
- 18 Second profile element
- 19 Floor frame
- 20 Side frame
- 21 Cover frame
- 22 Floor corner element
- 23 Side corner element
- 24 Cavity
- 25 Cavity
- 26 Floor receiving groove
- 27, 27 a, 27 b Side wall receiving groove
- 28 Seat rail construction
- 29 Hook
- 30 Cavity receiving pin
- 31 Seat rail receiving pin
- 32 Side wall web
- 33 Distal end
- 34 Curving groove
- 35 Recess
- 36 Cavity receiving pin
- 37 Curving groove
- 38 Edge bead (hook)
- 39 First floor layer
- 40 Second floor layer
- 41 Third floor layer
- 42 Floor edge
- 43 Bend
- 44 Oblique surface
- 45 Edge bead
- 46 First side wall layer
- 47 Second side wall layer
- 48 Third side wall layer
- 49 Side wall edge
- 50 Rod
- 51 Lug
- 52 Mould
- 53 Inner surface
- 54 First moulding tool
- 55 Inner surface
- 56 Second moulding tool
- 57 Corner region
- 58 Side wall corner region
- 59 Corner region
- 60 Bore
- 61 Edge chamfer
- 62 Recess
- 63 Bolt
- 64 Nut
- 65 Flange segment
- 66 Head
- 67 Line
- 68 Lines
- 69 Arcuate segment
- 70 Arcuate segment
- 71 Protrusion
- 72 Arrow
- 73 Corner element
- 74 Third cavity receiving pin
- 75 Bore
- 76 End corner element

Claims

1. A freight receiver device, in particular a freight container or pallet, in particular for loading aircraft, comprising at least one floor element and at least one profile element connected with the floor element, wherein at least one edge segment of the floor element is detachably connected with the at least one profile element via a connecting device comprising at least one hook.

2. The freight receiver device according to claim 1, wherein the connecting device is formed such that a connection can be created between the floor element and profile element by push-fit with subsequent rotation.

3. The freight receiver device according to claim 1, wherein the connecting device comprises a least one groove and at least one spring.

4. The freight receiver device according to claim 3, wherein a cross section of the groove and/or spring is formed round, in particular circular, at least in segments.

5. The freight receiver device according to claim 3, wherein the spring and/or groove are asymmetric such that the spring can be introduced into the groove at a predetermined first relative angle thereto and is hooked with the groove at a predetermined second relative angle.

6. The freight receiver device according to claim 3, wherein a cross section of the groove, apart from a groove opening, is circular, and/or a cross section of the spring has a length L in a longitudinal direction and a width B in a width direction, wherein the longitudinal direction L is perpendicular to the width direction B, wherein length L is greater than width B.

7. The freight receiver device according to claim 3, wherein a cross section of the spring has an arcuate segment and opposite the arcuate segment a rotation-support protrusion.

8. The freight receiver device according to claim 1, wherein at least one floor element edge segment of the floor element and/or at least one profile edge segment facing the floor element edge segment of a profile element is hook-shaped in cross section.

9. The freight receiver device according to claim 1, wherein at least one floor element edge segment of the floor element is curved inward and/or a profile element edge segment facing the floor element edge segment of the floor plate is chamfered downwards in the direction of the floor plate.

10. The freight receiver device according to claim 1, wherein the floor element and/or at least one preferably pultruded profile element is produced at least in sections of fibre-reinforced plastic, in particular comprising carbon fibres and/or fibre-reinforced carbon or glass fibres.

11. The freight receiver device according to claim 1, for example a freight container or pallet, in particular for loading aircraft, comprising a floor element wherein a floor element edge segment is connected with a multiplicity of profile elements, wherein the profile elements are connected together via a multiplicity of push-fit connections, wherein two adjacent profile elements only at their ends facing away from the respective other profile element each form a push-fit connection with a third profile element.

12. The freight receiver device according to claim 11, wherein several corner elements are provided which are each connected by a push-fit connection with two profile elements, wherein an end corner element is provided which is connected with maximum one profile element via a push-fit connection.

13. The freight receiver device according to claim 12, wherein several corner elements are provided with two push-fit connecting pins, wherein an end corner element is provided which comprises maximum one push-fit connecting pin.

14. The freight receiver device according to claim 1, wherein at least one wall element and at least one profile element comprising a slot is provided, wherein one preferably widened, preferably peripheral edge of the wall element is or can be inserted in the slot.

15. The freight receiver device according to claim 1, wherein at least one wall element is provided which comprises at least one bracing, in particular comprising an additional wall layer, running from one wall corner to the diagonally opposed wall corner.

16. A method for production of a freight receiver device according to claim 1, comprising at least one floor element and at least one profile element connected with the floor element, wherein the floor element and profile element are brought together at a first predetermined angle and then hooked by rotation.

17. The method according to claim 16, the freight receiver device comprising at least one floor element and a multiplicity of profile elements which are connected with an edge of the floor element, wherein several profile elements are connected with two adjacent profile elements via a push-fit connection, wherein two adjacent end profile elements only at their ends facing away from each other are each connected with a third profile element via a push-fit connection.