Patent Application
20190276134
The invention relates to a cargo deck of an aircraft and a method for manufacturing a floor module.
Cargo brought into the hold of an aircraft through a door must be introduced into said hold and be secured in the hold. The floor of such a cargo compartment, which is part of the cargo deck, is preferably of modular design, as is known, for example, from EP 1 646 556 B1.
A major problem in the construction of such a cargo floor is the conflicting demands for great stability and low weight. In addition, neither the individual components nor their installation should be too costly, as this increases costs.
Furthermore, the cargo floor should be watertight and fireproof and prevent liquid from penetrating, for example into the bilge.
Both for the production and for the assembly of cargo floors, it is important that this should be as simple as possible.
The invention is based on the object of providing a cargo deck with floor modules of an aircraft that eliminates the problems described above. In particular, a cargo deck and a manufacturing method for a floor module that is simple and highly functional or efficient shall be described. The cargo deck shall have high stability and water resistance or water impermeability at low weight. Furthermore, gas tightness is required in many applications, so that extinguishing gas, e.g. halon, can be introduced in the event of fire into certain areas without escaping. Under no circumstances shall the extinguishing gas be allowed to reach the passenger compartment and/or the cockpit from the cargo compartment. In general, these properties should be accompanied by low manufacturing and installation costs.
The object is solved by a cargo deck according to claim 1 and a manufacturing method according to claim 9.
In particular, the object is solved by a cargo deck of an aircraft which comprises a series of at least two floor modules arranged side by side and made of a fiber-composite material, wherein the floor modules each comprise at least one core in the form of a foam core and/or structural core which is interposed between a first cover layer made of fiber-reinforced plastic and a second cover layer made of fiber-reinforced plastic. In accordance with the invention, the floor modules each comprise a coreless peripheral edge region for producing a materially bonded connection between the cover layers, wherein the floor modules are arranged in such a way that sections of the coreless edge regions of the floor modules arranged side by side overlap one another, wherein at least one seal, in particular a sealing strip, is provided between the overlapping edge regions.
A core element of the present invention, therefore, consists of producing floor modules as fiber-composite materials, wherein these modules, arranged next to each other, form an (essentially) water-impermeable, (essentially) gas-impermeable and a walkable surface. The water- and/or gas-impermeable surface can be achieved by overlapping the floor modules in sections, especially where the edge regions are provided. In addition, a sealing strip can be provided to compensate for unevenness. The sealing strip can consist of silicone tape.
In one embodiment, the sealing strip has a thickness of approx. 1 to 5 mm, in particular approx. 2.5 mm. The sealing strip can have a width of approx. 1 to 4 cm, preferably approx. 2 cm.
An appropriate width and thickness are sufficient to effectively seal the floor modules against each other and/or against elements on which they are supported.
In one embodiment, the sealing strip is pre-assembled before the floor modules are inserted into the cargo deck, especially on the floor modules. For this purpose, the sealing strip may include an adhesive layer, which enables the sealing strip to be bonded to at least one of the floor modules, particularly at the edges. The sealing strip can be glued in sections to a floor module or be attached to the entire peripheral edge.
The core can, as explained above, either be made of foam or of structural elements. Honeycomb or other polygonal shapes, which are known in the field of manufacturing processes for fiber-reinforced materials, are suitable structural elements. The core is thus made of much lighter material than the cover layers. The result is essentially a sandwich structure, wherein the cover layers are glued together at the edges, however. This results in an extremely rigid and stable floor module. The well-known honeycomb structure is referred to by way of example with regard to an example of a structural core. The core of at least one floor module may include recesses into which inserts are inserted to accommodate transport balls. Preferably the recesses have a diameter and/or a side length of at least approx. 2 cm, in particular of at least approx. 5 cm. Corresponding recesses can have a circular, elliptical or rectangular shape.
The provision of recesses makes it possible to partially provide functional elements within the respective floor module. The inserts allow these functional elements to be replaced and prevent the recesses from leading to a structural weakening of the respective floor module. The inserts can be made of a plastic and/or a metal alloy, for example aluminum. According to the invention, it is also conceivable to manufacture the inserts as a fiber-composite material or a plastic.
An integrated construction method using the floor layer and the cover layer, which were combined to form a monolithic structure, can also be implemented according to the invention. In this embodiment, the cover layers, e.g. floor (bottom) and cover (top) layers, can be joined together (e.g. by local removal of the core) to form a monolithic body approx. 3-4 mm thick with an area of approx. 5 cm in diameter. The mounting for the ball element can be created by means of an abrasive process, e.g. by milling or cutting out. This manufacturing process is efficient and cost-effective.
At least one of the transport balls can be rotatably mounted in a housing that can be inserted into one of the inserts. Preferably the housing has a latch so that a latched connection to the insert can be established. The latched connection also ensures safe and efficient operation of the transport ball.
In general, it should be noted that appropriate transport balls are known in this field in order to transport heavy loads, such as containers and/or freight pallets, on the cargo deck.
According to the invention, corresponding transport balls are integrated into the floor modules in such a way that retrofitting the cargo deck with ball mats or transport rollers is unnecessary. This can save further weight. The floor module itself can consist of several individual components, e.g. a lower module with integrated drainage troughs and an upper ball mat floor. The lower and/or upper module can be manufactured as described. A divisibility can be useful here for manufacturing, assembly and maintenance reasons, e.g. to enable cleaning of the drainage areas.
The installation of the transport balls before the floor modules are installed in the cargo deck also facilitates the installation of the cargo deck.
The overlapping sections of the edge regions may each comprise a lower edge section of a first floor module and an upper edge section of a second floor module. The lower edge section preferably has a downwardly inclined upper side and the upper edge section an upwardly inclined lower side. The inclination may be defined in such a way that it is defined in relation to a bearing surface of the floor modules on perforated rails, cross members and/or longitudinal members.
The inclination leads to the fact that pushing the modules together leads to a sealing of the modules against each other. The inclination also allows a module to be retrofitted and removed at a later date, which is arranged in a row between a large number of modules. Finally, the module can be detached, lifted and sucked out of the area below the upper edge section. The module can be inserted into a row retroactively in an appropriate manner. In one embodiment, adjacent edge sections lie on different planes, so that overlapping is possible even without the described inclination. In general, a seal in overlapping areas is preferable to a butt seal.
According to the invention, it is possible to glue individual edge regions of neighboring modules together. Preferably, a detachable connection, in particular a screw connection, is made between the edge regions. The floor modules according to the invention may have drill holes in the edge regions for this purpose.
In one embodiment, the overlapping sections of the edge region are screwed together at least partially, preferably using a clip groove or a snap nut. Bolting allows easy maintenance and assembly of the cargo deck.
The first cover layer and/or the second cover layer may comprise a plurality of fiber layers. The first and second cover layers may have a similar or identical layer structure. The first cover layer preferably differs from the second cover layer in its layer structure. The layer structure can thus be designed and optimized with regard to the loads that occur, e.g. more fibers in the upper layers, in order to minimize the risk of damage caused by the cargo.
The fiber layers used can be bidirectional or multidirectional fabrics. The fibers used may include carbon fibers and/or aramid fibers and/or glass fibers.
In one embodiment, at least one of the cover layers has a thickness less than 3 mm, in particular less than 2 mm.
The first cover layer - preferably the upper cover layer—may comprise fiber layers of glass fibers and carbon fibers. In one embodiment, a ±45° carbon fiber layer is enclosed by a 0°/90° glass fiber layer. The following structure may, therefore, result for the first surface course:
According to the invention, the first cover layer can also be made of a uniform material, e.g. only glass fiber or only carbon fiber.
Preferably the glass fiber layers are S2 glass fiber layers.
The structure of the second cover layer can be as follows (from outside to inside, towards the core):
According to the invention, the second cover layer can also be made of a uniform material, e.g. only glass fiber or only carbon fiber.
The above thickness specifications are particularly preferred if the core has a thickness of 5 to 12 mm, in particular 7 to 9 mm. This results in a total floor module thickness of less than 2 cm, in particular less than 1.5 cm. According to the invention, the thickness specifications can vary in the range of +/−50%, preferably in the range of +/−30%.
In one embodiment, the floor modules are equipped with significantly stronger cores. This may be necessary, for example, if holders for transport balls are provided in the floor modules. This leads to high point loads which can be absorbed by stronger floor modules. According to the invention, the core in this case has a thickness of 8 to 30 mm, in particular 10 to 20 mm. This can result in a total floor module thickness of less than 4 cm, in particular less than 2.5 cm. According to the invention, the thickness specifications can vary in the range of +/−50%, preferably in the range of +/−30%. Even in this embodiment, there may be coreless areas with a thickness of less than 8 mm, in particular less than 6 mm. The coreless area with a thickness of 3 to 5 mm is preferred. This can rest on cross members and/or profiles running in longitudinal direction, e.g. U-profiles for the accommodation of roller drive units and/or transoms.
In one embodiment, an S2 glass fiber layer is located on the outside of the floor module (both on the first cover layer and on the second cover layer). This improves fire safety and prevents rapid wear of the respective module (high impact resistance).
At least one of the floor modules may comprise a local layer elevation for forming the edge region and/or a support section and/or for forming one of the receptacles for a functional element, in particular the transport balls, and/or for forming a drainage trough.
The elevation of the layers leads to an increased stability in the respective area. In one embodiment, the edge regions comprise additional layers of carbon and/or aramid and/or glass fibers.
In addition, the number of layers can be increased at those points where recesses are provided, e.g. to accommodate functional elements. It is also conceivable to increase the number of layers in various areas above recesses where the core has been removed and to exert so much pressure at these points during production of the respective floor module that the first and second cover layers contact each other and form a material bond during curing. Due to the increased number of layers, corresponding areas can be used as fixing points or for other applications. Ultimately, it is possible to create functional areas in the respective floor modules during production, which can be used as lashing points, for drainage, etc.
This leads to a weight reduction and simplifies installation.
At least one edge of the floor module may have an upwardly curved and/or upwardly sloping section to cover the fuselage. At an edge only if the floor module is mounted in the area of the aircraft door. Otherwise, these curved sections may be provided on both sides of a floor module. This results in a further simplification in the manufacture and assembly of the overall arrangement. In addition, the section, which is curved compared to the flat surface of the cover element, leads to a stiffening of the overall arrangement. In general, however, two cores can also be arranged next to each other in this concrete design of the floor module. In the area between the cores, a coreless area is provided, e.g. for mounting on a longitudinal beam, at which the cover layers are connected to form a material bond.
The floor module preferably has connecting elements in some areas between the cover layers. This results in an increased stiffness of the overall arrangement. Such a connecting element can, for example, comprise pipe sleeves by means of which fastening means, in particular screws for fastening cargo handling systems, e.g. tie-down elements, can be connected directly to cross members of the cargo hold. In this case “killing two birds with one stone” applies: Fastening of the floor module, transfer of tractive forces into the aircraft structure.
As already explained, the floor module is preferably designed as a hybrid composite part, e.g. with carbon and/or glass fiber reinforcement. This means that the desired three-dimensional shape can be achieved in a heatable press mold, ensuring particularly efficient production of the floor module with high strength and low weight.
It follows from the above that a method for producing a described floor module or cargo deck is also claimed to be in accordance with the invention.
The object mentioned above is also solved by a floor module for a cargo deck, which includes:
The object mentioned above is also solved by a method for the production of a floor module for a cargo deck of an aircraft.
The method shall preferably include the following steps:
A core element of the manufacturing method according to the invention is that functional elements of the cargo deck are integrally formed in the floor modules. In the manufacturing method described, these are inserts for holding transport balls.
The curing temperature can be in a range of 60 to 200° C., preferably in a range of 130 to 150° C. Preferably a temperature of more than 100° C. is maintained for a period of 20 to 80 minutes, in particular 25 to 60 minutes. Curing can be carried out simultaneously under pressure, e.g. in a press. Preferably a pressure between 60 and 100 N/cm2, e.g. 75 N/cm2, is applied.
The inserts can be made from the materials already explained in connection with the device. It is important for the function that these inserts are bonded to the entire fiber-composite material. The synthetic resin required for the manufacture of the vehicle composite material leads to the necessary material bond during the manufacturing process. Preferably pre-impregnated fibers, so-called “prepregs”, are used, which have a resin content of more than 40% (mass content), in particular of more than 47%. The resin content can be in the range of approx. 47-50%. With this resin content, a good bond to the core or core layer and a high surface quality is achieved. The upper limit of approx. 50% resin content ensures an advantageous final weight and prevents the formation of sticky surfaces.
The method described may include cutting out recesses corresponding to the recesses in the core layers in at least some of the fiber layers. Cutting can be done either before the fiber layers are placed or when the insert is inserted.
The described steps b) to d) can be carried out in a press with a press table and a press ram or press punch. This is preferably a heated press so that the floor module is manufactured under pressure and heat, so that the fiber-composite material hardens quickly and in a defined manner. As an option, the heating can also be integrated into the mold.
The press, in particular the tool, may include positioning aids, with at least some of the frame parts arranged on or surrounding the positioning aid. The positioning aids are designed in such a way that they have a certain elasticity, which makes it possible to compensate for the dimensional changes between the tool and the composite material caused by temperature changes during the curing process. This avoids stresses that would otherwise arise between the composite component and the molding/positioning aid during the cooling process, which would lead to damage or at least to more difficult demolding, which is particularly important for components with several positioning aids. For example, the positioning aids can at least partially consist of an elastomer.
The positioning aids can be disc-shaped elements, which ensure efficient insertion of the frame parts into the fiber-composite material. It is conceivable to provide sharp edges on the positioning aids to ensure that fiber layers and/or the core are cut through.
Making at least one of the inserts may include inserting first frame parts from a first side of the core and inserting second frame parts from a second side such that a first frame part and a second frame part engage in each case into each other, preferably to form a latching connection.
In one embodiment, the first frame part is arranged in the mold, preferably by using the positioning aids. Then synthetic resin impregnated (prepreg) fiber layers are inserted. The core is placed on the fiber layers and further fiber layers are positioned above the core. Finally, the second frame parts can be inserted into the core from the other side, penetrating the upper fiber layers. The final fixing of the frame parts into each other can take place in the course of closing the press.
The method may include the insertion of additional fiber layers prior to step (d) in such a way that there is a local increase in the number of layers in partial areas of the floor module so as to produce support and/or attachment areas and/or local reinforcements. In one embodiment, corresponding additional fiber layers are provided in the edge region of the respective floor module, which is essentially coreless. The additional fiber layers can, for example, be two 0°/90° layers with a layer thickness of approx. 0.9 mm each.
In one embodiment, at least some sections are provided with recesses in the core, wherein pressure is exerted on the sections by means of an appropriately designed tool in such a way that the first and second fiber layers are bonded together. This results in the advantages that have already been explained in this context with regard to the device.
The edge regions can be at least partially cured in such a way that at least sections of the edge regions are inclined relative to a support plane of the floor module, in particular at an acute angle.
After the floor module has been manufactured, at least one housing with a transport ball can be snapped into at least one of the inserts. In addition or alternatively, sealing strips can be glued on in the form already explained. It is also possible to attach fixing points to the floor modules.
In one embodiment, the tools of the press are roughened by sandblasting in particular. Preferably, at least a roughening of the tool which produces the upper side of the floor module is carried out. Due to the rough surface of the tool, a rough structure is obtained at least on the upper side of the floor module, which allows safe walking on the floor module (“anti-slip function”). The floor module, therefore, has a non-slip finishing layer. The roughening can take place locally, i.e. on relevant, e.g. accessible, partial areas. Preferably, connection surfaces that are not accessible from above when installed are not produced with a roughened tool in order to keep the manufacturing process as efficient as possible.
The method may involve the formation of a drainage trough, for example using an appropriate tool. The structural design of the drainage trough can be carried out in one pressing step, in which heat for curing is preferably applied at the same time. The formation of the drainage trough may involve the insertion of additional fiber layers, as described above. In the pressing step, drainage channels can also be created which are suitable for draining liquid from the floor modules into the drainage trough.
The formation of the drainage trough may be followed by a step of providing an opening and/or an outlet, e.g. in the form of a discharge nozzle.
In the following, several embodiment examples of the invention are explained in more detail by reference to the illustrations, wherein:
In the following description, the same reference numbers are used for identical and equivalent parts.
Floor modules 20, 20′ according to the invention can be used as area modules for both the upper cargo deck 110 and the lower cargo deck 120.
In
A front edge section 22a is located at the front side of the front floor module 20 and a rear edge section 22b is located at the rear side of the front floor module 20. Corresponding edge sections 22a, 22b are also provided on the rear floor module 20′. It can already be seen from
The overlapping front and rear edge sections 22a, 22b of the two floor modules 20, 20′ are described in
Both
The floor modules 20, 20′ according to the invention are rectangular in the embodiment example described and have a large number of holes 23, 23′, 23″ which are provided both in the left and right edge sections 21a, 21b and in the front and rear edge sections 22a, 22b. According to the invention, however, floor modules 20, 20′ can also be manufactured with dimensions specially adapted to the requirements of the respective aircraft. For example, any essentially square or triangular surfaces can be produced, which are particularly advantageous for covering the cargo deck in the narrowing rear area.
The holes 23, 23′ in the left and right edge sections 21a, 21b allow the floor modules 20, 20′ to be screwed to the longitudinal members 40′ and 40 respectively. The holes 23 in the front and rear edge sections 22a, 22b allow the floor modules 20, 20′ to be screwed together as described above. In summary, this results in a continuous chain or series of floor modules spanning the entire upper cargo deck 120 in the longitudinal direction of the aircraft.
According to the invention, the floor modules 20, 20′ can also be equipped with integrated functional units, for example a transport ball 56 (see
In the floor modules 20, 20′, in particular in the area where the flat structure core 25 is intended, recesses can be made in which inserts 50 are integrated (see
The inserts can be used to hold a housing of a transport ball 56 (see
In one embodiment example, the insert 50 has an undercut 53 (see
A corresponding insert is particularly advantageous for the manufacturing method of the floor modules 20, 20′ according to the invention.
A corresponding production preferably takes place in a press 60, as shown, by way of example, in
In one embodiment example of the manufacturing method, the press table (or mold) 62 comprises, in addition to a frame 66 for producing the inclined front and rear edge sections 22a, 22b, positioning elements 65, 65′, 65″, which are distributed over the press table. To produce a floor module according to the invention, these positioning elements 65, 65′, 65″ are equipped with upper frame parts 52, as shown in
According to the invention, numerous variants are conceivable. As can be seen from
There is an opening in the center of the drainage trough 71 on the underside of which there is a discharge nozzle 73 (see
In one embodiment example, a sieve is provided to prevent clogging of the drainage system. In the embodiment example shown in
The drainage trough 71 can be designed as part of the manufacturing method in accordance with the invention in such a way that it extends into an area below the support level 7. The deepest point of the drainage trough 71 can be at least 1.5 or 2.5 cm away from this support plane 7. In one embodiment example, the drainage trough 71 is manufactured in a coreless area, with an increased number of fiber layers, e.g. carbon fiber layers, being provided depending on the application. The structure of the drainage trough 71 can be created by pressing the floor module 20 with a suitable tool. In this pressing step, the fiber-composite material can be cured simultaneously.
1 Container
2 Cargo space
4 Clip groove
5 Screw
7 Support plane
20, 20′ Floor module
21
a,
21
b Left and right edge section
22
a,
22
b Front and rear edge section
23, 23′, 23″ Holes
25 Structure core
26
a,
26
b Cover layer
27
a,
27
b Additional layers
30 Sealing strip
40, 40′ Longitudinal member
41, 41′ Perforated rail
50 Insert
51 Lower frame part
52 Upper frame part
53 Undercut
55 Housing
56 Transport ball
57 Detent
60 Press
61 Press plunger
62 Press table
65, 65′, 65″ Positioning elements
66 Press frame
70 Drainage system
71 Drainage trough
73 Discharge nozzle
75 Drainage screws
76 Drainage nuts
101 Outer skin of aircraft
110 Upper cargo deck
120 lower cargo deck
| Number | Date | Country | Kind |
|---|---|---|---|
| 102018105278.2 | Mar 2018 | DE | national |
| 102018108950.3 | Apr 2018 | DE | national |
