Apparatus and method for manufacturing structural elements in composite materials
By designing equipment that adjustable support frames and laminated mandrels, the problem of difficult to meet the dimensions and shape requirements when manufacturing composite structural components in the prior art is solved, a rapid and economical production process is achieved, and the equipment is improved. Flexibility and efficiency.
Patent Information
- Application Number
- CN202380034147.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-04-14
- Filing Date
- 2023-04-12
- Publication Date
- 2025-01-17
AI Technical Summary
The prior art is difficult to quickly and effectively meet the needs of different sizes and shapes when manufacturing composite structural elements, and the equipment is complex, making overall preparation time and process optimization difficult to achieve.
A device including a support frame and a laminated mandrel is designed, through adjustable head and longitudinal beams, combined with linear actuators and restraint members, to adapt to structural elements of different sizes, to achieve lamination and curing operations, and It allows the manufacture of structural elements with different longitudinal axes and axial cavity on the same device.
The rapid and economical manufacturing of composite structural components is achieved, the production process is simplified, the manufacturing cost and time is reduced, and it is suitable for structural components of different sizes and shapes, improving the flexibility and efficiency of the equipment.
Smart Images
Figure CN119325421A_ABST
Abstract
Description
[0001] CROSS-REFERENCE TO RELATED APPLICATIONS
[0002] This patent application is related to Italian Patent Application No. 102022000007511 filed on April 14, 2022, the disclosure of which is incorporated herein in its entirety by reference. Technical Field
[0003] The present invention relates to an apparatus and a method for manufacturing a structural element in a composite material having a longitudinal axis and an axial cavity.
[0004] It should be noted that the term "for manufacturing a structural element in a composite material" not only covers operations or steps for manufacturing a structural element (including channels in an autoclave), but also covers subsequent operations or steps of testing and finishing a previously manufactured structural element, and any further operations or steps of assembling the structural element with other structural elements.
[0005] In particular, the invention has advantageous, but not exclusive, application in the construction of closed or open structural elements, such as aircraft fuselages or fuselage sections. Background Art
[0006] The following description will make explicit reference to structural elements of the above type made of composite materials known in the aerospace field, without loss of generality. The use of such materials is driven by the need to reduce the overall weight of the aircraft and to eliminate or minimize corrosion problems of the aircraft structure.
[0007] In the most common solutions, the composite material used is a fiber material (e.g. carbon fiber) pre-impregnated with epoxy resin, BMI or other uncured or pre-cured material. The material is deposited in a mold and then processed under temperature and pressure. Other methods use dry fibers, usually impregnated with a fluid resin according to a well-known method (e.g. by a method called "resin transfer molding" or RTM).
[0008] Typically, structural elements of the above-mentioned type, such as fuselages or portions thereof, are made by combining a skin in composite material with a plurality of reinforcing stringers, also made in composite material and typically positioned parallel to the axis of the fuselage or portion thereof.
[0009] In particular, each stringer is typically defined by a thin-walled longitudinal cross-section beam comprising:
[0010] one or two transverse longitudinal flanges adapted to be joined to the skin; and
[0011] A raised portion of a predetermined geometric shape that protrudes laterally relative to the flange.
[0012] The stringers most commonly used in industry have ω, T, L, J or Z cross sections.
[0013] The cycle for constructing these types of structural elements or parts thereof generally comprises the following steps:
[0014] preparation;
[0015] trimming and / or drilling;
[0016] Non-destructive testing and dimensional testing;
[0017] Surface finishing; and
[0018] Assemble.
[0019] The most common of the many methods used to produce structural elements of the above-mentioned type are listed below.
[0020] According to a first operating mode, in order to produce a stringer, a plurality of layers of uncured composite material are placed on a forming tool of appropriate shape.
[0021] Once the stringers are produced, they are removed from the forming tool and placed in corresponding recesses of a tool called mandrel; after this operation, in order to produce the skin, further layers of uncured composite material are laminated and overlapped with the stringers placed in the recesses of the mandrel.
[0022] The assembly thus formed then undergoes a co-curing operation in an autoclave by applying appropriate pressure and temperature in order to cure the composite material, compact the preceding layers together and bond the stringers to the skins.
[0023] In practice, each stringer is rigidly and integrally applied to one face of the skin, generally the face defining the inner wall of the skin, ie the face that, in use, faces toward the interior of the fuselage.
[0024] This completes the steps of manufacturing the structural element.
[0025] According to another mode of operation, the skin, made by laminating together a plurality of layers of uncured composite material, is bonded by means of a structural adhesive to the stringers which are precured after their formation.
[0026] In this case, the assembly thus formed is also placed in an autoclave and subjected to appropriate pressure and temperature in order to cure the fresh composite material, compact the several layers together and bond the stringers to the skins. This operation is generally known in the industry as co-bonding.
[0027] The co-bonding operation may also be performed by pre-curing only the skin and bonding the skin to the uncured stringers by means of a structural adhesive.
[0028] According to another mode of operation, both the skin and the stringers can be pre-cured and then bonded by means of a structural adhesive. This operation is generally referred to in the industry as bonding and can be performed in an autoclave or at low temperatures.
[0029] Depending on the specific application, there are also constructions in which the longitudinal stringers are incorporated into the skin, or other so-called sandwich constructions in which two skins are separated by a closed or open-cell filler.
[0030] Likewise, the skin is laminated onto the mandrel and cured with appropriate reinforcements (sandwich layers, incorporated skins, etc.) at appropriate pressure and temperature.
[0031] In summary, in co-curing, the parts to be cured (skin and stiffener) are "fresh", in co-bonding, one of the elements (skin or stiffener) is already cured, and in bonding, both elements are cured.
[0032] Once the curing process is complete, the structural element thus formed is trimmed according to the needs of the project (the laminate of the skin is increased from nominal) and drilled if necessary.
[0033] Once the structural elements are obtained, as requested by the project, they are subjected to non-destructive testing to verify their feasibility.
[0034] It is also dimensionally measured to check for any "out of tolerance".
[0035] As a result of this testing, rework may be required, if necessary, to restore the product characteristics required for the project.
[0036] The application of protective coatings is a necessary and preparatory action for the next step; the composite material must be protected from contact with metallic materials, especially aluminum, UV rays, moisture and anything else the project requires.
[0037] Once all the above operations are completed, the process of manufacturing these structural elements is completed by installing on them the other reinforcing and non-reinforcing elements that are required for the project and complete their construction.
[0038] There is a need in the art to optimize the process of manufacturing these structural elements by minimizing the overall preparation time and process.
[0039] Furthermore, and for the same reasons, it is also necessary to create a single piece of equipment that allows the entire production cycle described above to be completed in a simple and efficient manner.
[0040] Finally, it is also necessary to use the same apparatus to manufacture structural elements having different longitudinal and diametrical dimensions relative to the longitudinal axis, so that the same apparatus can be used for different applications and / or procedures. Summary of the invention
[0041] An object of the present invention is to provide a device for manufacturing structural elements in composite materials having a longitudinal axis and an axial cavity, which device is highly reliable and cost-effective and allows satisfying the needs specified above, as well as at least one of the requirements associated with the devices of known type and described above.
[0042] According to the invention, this object is achieved by a device as claimed in claim 1 .
[0043] Another object of the invention is to provide a method for manufacturing a structural element in a composite material having a longitudinal axis and an axial cavity, which method allows to meet in a simple and inexpensive way the needs specified above, as well as at least one of the requirements associated with the methods of known type and described above.
[0044] According to the invention, this object is achieved by a method as claimed in claim 13 . BRIEF DESCRIPTION OF THE DRAWINGS
[0045] For a better understanding of the present invention, preferred non-limiting embodiments of the present invention will be described below by way of example only and with the aid of the accompanying drawings, in which:
[0046] Figure 1 is a perspective view of a structural element in composite material, in particular a portion of an aircraft fuselage, manufactured using the apparatus and method according to the invention, with some parts removed for clarity;
[0047] Figure 2 is used to manufacture according to the present invention Figure 1 A perspective view of a support frame of the apparatus of the structural elements in the embodiment of the present invention, with some parts removed for clarity;
[0048] Figure 3A is a front view of a laminating mandrel of an apparatus according to the invention, the laminating mandrel being intended to be mounted on Figure 2 and arranged in a retracted position with some components removed for clarity;
[0049] Figure 3B It is carried by a transport trolley Figure 3A A small perspective view of the lamination mandrel in ;
[0050] Figure 4 yes Figure 3A and Figure 3B A perspective view of a central shaft of a laminating mandrel in FIG. 1 , the laminating mandrel being equipped with a linear actuator with some components removed for clarity;
[0051] Figure 5 yes Figure 4An exploded perspective view of a possible variant of the central axis of Figure 4 The central axis of the invention is composed of a base module and an auxiliary module with some parts removed for clarity;
[0052] Figure 6 and Figure 7 They are Figure 4 A perspective view of a base module and auxiliary modules of a variation of FIG during assembly and fitting together, with some parts removed for clarity;
[0053] Figure 8 is a perspective view of an apparatus according to the present invention in a preparatory step for a lamination operation with uncured or precured composite material, with some parts removed for clarity;
[0054] Fig. 9 yes Figure 8 a side view of a detail in which some parts are removed for clarity and some parts are shown in an exaggerated scale;
[0055] Fig. 10A and 10B is Figure 8 a side view of the interior details of a lamination mandrel shown with some components removed for clarity and with some components shown at an exaggerated scale;
[0056] Fig.11 is in a further preparation step for the lamination operation Figure 8 A perspective view of the device shown in FIG. 1 with some components removed for clarity and some components shown on a small scale, wherein Figure 4 The central axis and linear actuator in Figure 3B The trolley shown in is extracted from the rest of the apparatus;
[0057] Fig.12 yes Figure 8 a side view of the apparatus in FIG. 1 at the end of a lamination operation, with some components removed for clarity and some components shown at a reduced scale;
[0058] Fig.13 yes Fig.12 a side view of the device at the end of the curing and finishing cycle; and
[0059] Fig.14 yes Fig.13 Side view of the device in Figure 5 after the lamination mandrel has been extracted from the cured structural element and at a stage in which the structural element is supported only by the supporting frame. DETAILED DESCRIPTION
[0060] Reference Figure 1, numeral 1 denotes as a whole a first example of a structural element in a composite material manufactured using the apparatus and process that are the object of the present invention.
[0061] In particular, the present description will explicitly refer to structural elements used in the aeronautical field, such as aircraft fuselages or fuselage sections, and to processes for manufacturing these structural elements, without loss of generality.
[0062] According to the preferred embodiment described and illustrated herein, the structural element 1 is intended to be a part of an aircraft fuselage (known per se and not illustrated).
[0063] In more detail, the structural element 1 has a longitudinal axis A and is provided with an axial through cavity 2. In practice, the structural element 1 is a solid of revolution having axis A;
[0064] Alternatively, the structural element 1 may also be substantially similar to a solid of revolution having an axis A. For example, it may also not have a constant cross section along the axis A and may have a configuration that tapers towards one of its axial ends. The structural element 1 comprises a skin 3 made of composite material and a series of hollow longitudinal reinforcing stringers 4 having closed sections.
[0065] The stringers 4 extend parallel to the axis A and in the present case along the entire axial length of the structural element 1 .
[0066] In one embodiment, the composite material used is a fiber material, such as carbon fiber, pre-impregnated with epoxy resin, BMI or other uncured or pre-cured material. The material is deposited in a mold and then processed under temperature and pressure. Other methods use dry fibers, usually impregnated with a fluid resin according to a well-known method (for example, by a method called "resin transfer molding" or RTM).
[0067] In the solution depicted in the figures, the structural element 1 is obtained by applying stringers 4 rigidly and integrally to the skin 3 , such that each stringer 4 delimits with the skin 3 itself a hollow section having a closed contour.
[0068] As in Figure 1 As can be seen in the figure, each stringer 4 comprises two lateral flanges 5 suitable for being adhered to the skin 3, and a raised portion 6 centrally located between the flanges 5, which projects relative to the flanges 5 and has a concave shape on one side. In particular, in the example shown, the stringer 4 has an ω cross section.
[0069] Alternatively, the stringers 4 intended to form a closed hollow section with the skin 3 may have cross-sections of different shapes, for example, circular arcs, semicircular shapes, rectangular shapes, polygonal shapes, semi-elliptical shapes, semi-oval shapes, etc.
[0070] Figures 2 to 14 There is shown a piece of equipment (and its components) according to the invention for manufacturing a structural element 1. The equipment is indicated as a whole by the reference numeral 10.
[0071] In particular, the apparatus 10 comprises a support frame 11 ( Figure 2 ) and the laminating mandrel 12 (shown separately in Figure 3A The lamination mandrel 12 is mounted on the support frame 11 so that it can rotate about its own central axis B and defines an outer lamination surface 13, which, as will be explained in detail below, is intended to be laminated with one or more layers of composite material to be cured or pre-cured.
[0072] The supporting frame 11 basically comprises two vertical heads 14, 15 facing each other and parallel to each other, and one or more longitudinal crossbeams 16, in this case two, extending between the heads 14, 15 to connect them at a predetermined distance.
[0073] More specifically, the heads 14 , 15 are able to house the laminating mandrel 12 between them and, for this purpose, extend transversely, in particular orthogonally, to the axis B of the laminating mandrel 12 itself.
[0074] Each head 14 , 15 comprises a fixed part 17 and a movable part 18 which coaxially receives the laminating mandrel 12 and is rotatable about an axis B relative to the fixed part 17 .
[0075] from Figure 2 , Figure 8 and Fig.11 It can be seen that the fixed part 17 of each head 14, 15 surrounds the corresponding movable part 18 on the outside, which has a cylindrical external contour of the axis B and is mounted through the fixed part 17 itself by the insertion of washers and / or bushings (which are known per se and are not shown); in this way, the movable part 18 of each head 14, 15 can rotate around the axis B relative to the corresponding fixed part 17.
[0076] The two movable parts 18 of the heads 14 , 15 are centrally provided with a respective central through-opening 20 , 21 , which in this case have a circular contour and are identical to one another.
[0077] According to a possible alternative (not shown), in particular if it is necessary to make a structural element with a configuration tapering towards one of its axial ends, the opening of the movable part of the head may have a different diameter or size.
[0078] Preferably, each head 14, 15 is mounted on a respective pair of guide uprights 22 allowing height adjustment. In particular, the guide uprights 22 project downwardly from each head 14, 15 and the longitudinal crossbars 16 to define respective support feet 23 for resting the support frame 11 on the floor surface in case of stable positioning on the floor surface.
[0079] The longitudinal crossbeams 16 also have an adjustable length parallel to the axis B; for this purpose, according to a preferred embodiment, each longitudinal crossbeam 16 is formed by two beams 16 a , 16 b mounted coaxially so that they can slide on the guide rod 24 .
[0080] Furthermore, the longitudinal crossbars 16 are preferably provided with wheels 25 so that the device 10 can be moved after the heads 14 , 15 have slid on the respective guide uprights 22 , until the wheels 25 themselves come into contact with the floor surface and simultaneously make the supporting feet 23 disappear.
[0081] All described adjustments allow the support frame 11 to be adapted to different sizes of the lamination mandrels 12 and, therefore, to different sizes of the structural elements 1 to be manufactured, both in the longitudinal direction (ie parallel to the axis B) and in height.
[0082] The height adjustment of the heads 14, 15 also makes it easier to fit the entire apparatus 10 into autoclaves of different sizes, as will be explained in more detail below.
[0083] Reference Figure 3A , Figure 3B , Figure 4 , Figure 8 and Fig.11 , the lamination mandrel 12 comprises:
[0084] The central axis 26 of the axis B ( Figure 4 ), which in this case has a polygonal, in particular hexagonal, outline;
[0085] a plurality of sectors 30 angularly spaced about axis B; and
[0086] A plurality of linear actuators 31, in this case telescopic actuators or jacks, extend between the central axis 26 and the respective sectors 30 to enable the sectors 30 to be moved in an extended lamination position ( Figure 3B , 8 and 11) and the contraction position ( Figure 3A ) move between, in the extended lamination position, the aforementioned sectors 30 are adjacent to each other at the maximum distance from the central axis 26 and define the lamination surface 13, and in the contracted position, the aforementioned sectors 30 are adjacent to the central axis 26 and partially overlap each other.
[0087] Preferably, the central shaft 26 carries an externally cantilevered linear actuator 31 .
[0088] according to Figure 5 , Figure 6 and Figure 7 In the variation shown in , the central shaft (here indicated as 26') can be composed of a base module 26a' and one or more auxiliary modules 26b', which one or more auxiliary modules 26b' are optionally axially connected to one (27) or both (27, 28) of the ends of the base module 26a', or connected to the already assembled auxiliary module 26b' itself to increase the axial length of the central shaft 26'.
[0089] exist Figure 5 , Figure 6 and Figure 7 In the example shown, the central shaft 26 ′ is composed of a base module 26 a ′ which is identical in length to the central shaft 26 and an auxiliary module 26 b ′ which is coupled to the end 27 of the base module 26 a ′.
[0090] refer to Figure 3A , 3B , 10A, 10B and 11, the sectors 30 are composed of corresponding curved panels, which are bounded by corresponding inner surfaces 29a towards the central axis 26 and by corresponding outer surfaces 29b on the opposite sides, thereby forming corresponding parts of the laminated surface 13.
[0091] The sectors 30 have, on their outer surface 29 b , one or more longitudinal recesses or grooves 32 configured to receive previously formed stringers 4 prior to the step of bringing them into contact with the skin 3 , and to support the stringers 4 during the same step and in the subsequent curing step or operation, as better described below.
[0092] Conveniently, the process for manufacturing the structural element 1 also comprises, after the step of forming the stringers 4 and before the step of bringing the stringers 4 into contact with the skin 3, a step of positioning a longitudinal insert, generally called a “bladder” (not shown), inside the raised portion 6 of each stringer 4; in this way, each of the above-mentioned inserts will be completely housed in the cavity formed between the skin 3 and the corresponding stringer 4 once the skin 3 and the corresponding stringer 4 are in contact with each other.
[0093] refer to Figure 3A , Figure 3B , Figure 4 , Fig. 10A and Fig. 10B as well as Fig.11 Each linear actuator 31 includes a hollow housing or tubular sleeve 33 fixed to and cantilevered outwardly from the central shaft 26 , and one or more rods 34 that slide relative to the sleeve 33 and / or any other rods 34 .
[0094] By moving the rod 34 , each linear actuator 31 can adopt different overall lengths ranging from a minimum length to a maximum length; the rod 34 of each linear actuator 31 protrudes from the respective sleeve 33 at least in configurations other than the minimum length.
[0095] The maximum stroke of the rod 34 of each linear actuator 31 can be adjusted as a function of the configuration of the sectors 30 and of the maximum radial footprint of the laminating surface 13 defined by the sectors 30 themselves.
[0096] Advantageously ( Figure 2 , Figure 8 , Fig. 9 , Fig. 10A , Fig. 10B and Fig.11 ), the device 10 further comprises:
[0097] a first constraining member 35 for releasably connecting the sector 30 in the extended lamination position to the movable part 18 of the head 14, 15; and
[0098] A second restraining member 36 connects the linear actuator 31 to the sector 30 in a releasable manner so that the central axis 26 and the linear actuator 31 can be extracted from the supporting frame 10 when the sector 30 arranged in the deployed position is connected to the movable part 18 of the head 14, 15 via the restraining member 35.
[0099] In particular, in the example shown, the constraining members 35 comprise respective bolts 35 a extending parallel to the axis B and releasably connecting the movable portion 18 of the head 14 , 15 to the opposite axial end edges of the sector 30 .
[0100] In particular, each bolt 35a engages a corresponding hole 35b, 35c obtained in the movable portion 18 of the respective head 14, 15 and in the respective sector 30.
[0101] The sectors 30 are also connected to each other in an extended lamination position by a system of known type described in patent EP 2 644 359 B1 in the name of the same applicant.
[0102] According to a possible alternative (not shown), the constraining member 35 may be a closure or a connection which can be operated electronically to integrate the sector 30 with the movable part 18 of the head 14 , 15 .
[0103] In the example shown (see in particular the appendix Fig. 10A and 10B), each constraining member 36 comprises an engagement seat 37 obtained in the corresponding sector 30, and a coupling head 38 carried by the end rod 34 of the corresponding linear actuator 31 and suitable for being releasably coupled to the engagement seat 37 itself.
[0104] In detail, in the solution shown here, the coupling head 38 of each linear actuator 31 can be in a retracted configuration ( Fig. 10A ) and the expansion construction ( Fig. 10B ) in the contracted configuration, the coupling head 38 can freely enter or leave the corresponding coupling seat 37, and in the expanded configuration, the coupling head 38 radially protrudes relative to the rest of the rod 34, so that the coupling head 38 can be retained in the coupling seat 37 itself by being connected to the coupling seat 37 itself.
[0105] refer to Fig.14 The heads 14, 15 of the support frame 11 also include a plurality of clamping members 40, which are movable between a rest position and an operating position. In the rest position, the plurality of clamping members 40 are retracted in the corresponding heads 14, 15, and in the operating position, the plurality of clamping members 40 protrude from the corresponding heads 14, 15 and hold the opposite axial end edges of the cured structural element 1 to allow the lamination core shaft 12 to be extracted from the structural element 1 itself through the central opening 20 of the head 14.
[0106] In particular, the clamping member 40 is movable between a rest position parallel to the axis B and an operating position.
[0107] The clamping member 40 is also carried by the movable portion 18 of the respective head 14 , 15 .
[0108] With the clamping members 40 arranged in the operating position and holding the cured structural element 1 , the laminating mandrel 12 can be extracted from the structural element 1 based on a displacement performed by the linear actuators 31 when the sectors 30 go from the extended laminating position to the retracted position.
[0109] Insertion / extraction of the laminating mandrel 12 into / from the supporting frame 11 and insertion / extraction of the central shaft 26 with the linear actuator 31 into / from the sector 30 are preferably performed by Figure 3B and 11 The transport trolley 41 shown is used to perform the operation.
[0110] In particular, the transport trolley 41 comprises two horizontal longitudinal bars 42 on which wheels 43 are mounted and a head 44 orthogonal to the longitudinal bars 42 and covering the respective adjacent ends of the longitudinal bars 42 .
[0111] The longitudinal bar 42 is designed to slide, in use, under the longitudinal crossbar 16 of the support frame 11 so that the head 44 is positioned facing one of the heads 14 , 15 and parallel thereto.
[0112] The head 44 of the transport trolley 41 is also equipped with restraining means, known per se (and not shown), such as bolts, to connect the central axis 26 integrally to the head 44 in an orthogonal cantilever manner.
[0113] In use, to manufacture the structural element 1, the first step is to prepare the apparatus 10 for a lamination operation.
[0114] In particular, the sectors 30 connected to the respective linear actuators 31 via the constraining members 36 are arranged in a retracted position adjacent to the central axis 26 .
[0115] At this point, the laminating mandrel 12 with the sectors 30 in the retracted position is inserted, with the aid of the handling trolley 41 , into the supporting frame 11 passing through one of the central openings 20 , 21 of the heads 14 , 15 , between the heads 14 , 15 themselves.
[0116] By actuating the linear actuator 31, the sector 30 is then moved to the extended lamination position. Subsequently, the sector 30, which is still held in the extended lamination position, is moved by the restraining member 35 ( Figure 8 ) is connected to the movable part 18 of the head 14, 15.
[0117] At this point, the restraining member 36 may be released in order to disconnect the linear actuator 31 from the corresponding sector 30 and retract the linear actuator 31 toward the central axis 26 .
[0118] In this case, the central shaft 26 with the retracted linear actuator 31 is again removed from the support frame 11 ( Fig.11 ) and can therefore be used for other parallel applications, such as the manufacture of another structural element 1.
[0119] The operation of laminating the lamination surface 13 of the lamination mandrel 12 may then commence in a conventional manner.
[0120] In particular, previously formed, uncured or pre-cured reinforcing stringers 4 are inserted into corresponding grooves 32 of sectors 30 in combination with strips and bladders.
[0121] The skin 3 is then formed by laminating the necessary layers of uncured or precured composite material on the lamination surface 13, the stringers 4 and the different types of inserts placed in the grooves 32. Fig.12 ).
[0122] During the laminating operation, the sectors 30 rotate integrally with the movable part 18 of the heads 14 , 15 about the axis B.
[0123] At the end of the lamination operation, the device 10 with the laminated composite material is transferred to an autoclave (known per se and not shown) to undergo a curing cycle.
[0124] The transport can advantageously be performed by having the supporting feet 23 disappear into the respective heads 14 , 15 and having the wheels 25 rest on the floor surface, on which the wheels 25 can then slide.
[0125] At the end of the curing cycle, the support frame 11 and the sectors 30 are extracted from the autoclave in order to proceed with the conventional steps of completing the manufacture of the structural element 1 .
[0126] In particular, the cured structural element 1 is trimmed (laminate material of the skin 3 is increased from nominal) and, if necessary, drilled according to the requirements of the project. Fig.13 As can be seen in FIG. 1 , the opposite axial end edges of the cured structural element 1 are cut and subjected to a finishing operation ( Fig.13 ). These operations are performed while the laminating mandrel 12 is still mounted on the supporting frame 11 and externally carries the cured structural element 1 .
[0127] At this point, the central shaft 26 and the linear actuator 31 are then passed through the central opening 20 of the crossbeam 14 and reinserted into the sector 30 with the aid of the transport trolley 41. In addition, the linear actuator 31 is secured by means of the restraining member 36 ( Fig. 10B ) reconnect to sector 30.
[0128] The clamping members 40 are then moved from the rest position to an operating position in which they project from the respective heads 14,15 and hold the opposite axial end edges of the structural element 1. In practice, the structural element 1 is attached to the heads 14,15.
[0129] In this operating condition, the laminating mandrel 12 can be extracted from the structural element 1 on the basis of the displacement performed by the linear actuator 31 when the sectors 30 go from the extended laminating position to the retracted position.
[0130] The laminating mandrel 12 can then also be passed through one of the central openings 20 , 21 of the heads 14 , 15 and can again be withdrawn from the support frame 11 by means of the transport trolley 41 .
[0131] The longitudinal axis A of the structural element 1 produced in this way therefore coincides with the axis B of the lamination mandrel 12 .
[0132] In this case, due to the connection of structural element 1 to movable part 18 of head 14 , 15 , and therefore due to the possibility that structural element 1 itself can rotate about its axis A coinciding with axis B, a series of non-destructive tests can be performed to verify its feasibility.
[0133] The structural element 1 is also subjected to dimensional measurements to check for any "out of tolerance".
[0134] As a result of this testing, rework may be required, if necessary, to restore the product characteristics required for the project.
[0135] In this step, a protective coating may also be applied to the structural element 1 , thereby protecting the structural element 1 from contact with metallic materials, in particular aluminum, UV rays, moisture and any other substances required by the project.
[0136] Once all the above operations are completed, the process of manufacturing the structural element 1 is completed by installing on it the other reinforcing and non-reinforcing elements that are required for the project and complete its construction.
[0137] This step can also be advantageously performed by holding the structural element 1 connected to the movable part 18 of the head 14 , 15 of the supporting frame 11 .
[0138]
[0046] By examining the above-described and illustrated features of the apparatus 10 and the method of making the apparatus 10, the advantages achieved by the present invention will become apparent.
[0139] In particular, the solution described makes it possible in a simple manner to optimize the working area required for the production of a structural element 1 , such as an aircraft fuselage section having a constant or tapered section.
[0140] In fact, the manufacturing process including the actual manufacturing, finishing and drilling operations, quality and dimensional checks and any installation of additional reinforcement elements can be completely completed on the device 10, wherein it is possible to reuse a portion of the lamination mandrel 12 (central shaft 26 and linear actuator 31) in parallel to manufacture other structural elements, even if the other structural elements have different dimensions (e.g., axial length and diameter). This reduces the cost and time of the manufacturing process.
[0141] Furthermore, the apparatus 10 is extremely flexible and is suitable not only for manufacturing structural elements of different axial and radial dimensions, but also for fitting into autoclaves of different dimensions.
[0142] Finally, it is obvious that modifications and variations may be made to the device 10 and to the method of manufacturing said device 10 described and illustrated herein, without departing from the scope of protection defined by the claims.
Claims
1. A device (10) for manufacturing a structural element (1) of composite material, the structural element (1) having a longitudinal axis (A) and an axial cavity (2), the device (10) comprising: Support frame (11); and a laminating mandrel (12) mounted on the support frame (11) in a manner rotatable about its own central axis (B) and defining an external laminating surface (13) intended to be laminated with one or more layers of composite material to be cured or precured; Wherein, the support frame (11) comprises: two vertical heads (14, 15) facing each other and parallel to each other, said heads (14, 15) extending transversely to said central axis (B) of said laminating mandrel (12) in use and being capable of accommodating the laminating mandrel (12) itself between said two vertical heads (14, 15); and A longitudinal connecting device (16), the longitudinal connecting device (16) is used to longitudinally connect the heads (14, 15); Each head (14, 15) comprises a fixed part (17) and a movable part (18), the movable part (18) coaxially receiving the laminating mandrel (12) and being rotatable relative to the fixed part (17) about the central axis (B); Wherein, the laminated mandrel (12) comprises: a central axis (26, 26') defining said central axis (B); a plurality of sectors (30) angularly spaced about said central axis (B); and a plurality of linear actuators (31) extending between the central axis (26, 26') and the respective sectors (30) to move the sectors (30) themselves between an extended lamination position, in which the sectors (30) are adjacent to each other at a maximum distance from the central axis (26, 26') and define the lamination surface (13), and a retracted position, in which the sectors (30) are adjacent to the central axis (26, 26') and partially overlap each other; Wherein, the device (10) further comprises: first restraining means (35) for releasably connecting the sector (30) in the extended lamination position to the movable part (18) of the head (14, 15); and A second restraining device (36) which releasably connects the linear actuator (31) to the sector (30) so that the central axis (26, 26') and the linear actuator (31) can be withdrawn from the device (10) when the sector (30) arranged in the unfolded lamination position is connected to the movable part (18) of the head (14, 15) via the first restraining device (35).
2. The device according to claim 1, wherein The movable part (18) of at least one of the heads (14, 15) has a central opening (20, 21), through which the laminating mandrel (12) or the assembly formed by the central shaft (26, 26') passes and through which the linear actuator (31) can be inserted into / extracted from the supporting frame (11).
3. The device according to claim 2, wherein: The heads (14, 15) further comprise a clamping member (40) which is movable between a rest position in which the clamping member (40) is retracted within the respective head (14, 15) and an operating position in which the clamping member (40) protrudes from the respective head (14, 15) and holds the opposite end edges of the cured structural element (1) to allow the laminating core shaft (12) to be extracted from the structural element (1) itself through the central opening (20, 21).
4. The device according to claim 3, wherein: The clamping member (40) is movable between the rest position parallel to the central axis (B) and the operating position.
5. The device according to claim 3 or 4, wherein: The clamping member (40) is carried by the movable portion (18) of the respective head (14, 15).
6. The device according to any one of claims 3 to 5, wherein: Based on the displacement of the sectors (30) from the extended laminating position to the retracted position caused by the linear actuators (31), the laminating mandrel (12) is extracted from the cured structural element (1).
7. Apparatus according to any one of the preceding claims, wherein: Each linear actuator (31) comprises: a tubular sleeve (33) fixed externally to the central axis (26, 26'), and at least one rod (34) sliding relative to the tubular sleeve (33) to a set position, the set position protruding a different amount from the tubular sleeve (33) itself; and wherein the maximum stroke of the rod (34) of each linear actuator (31) can be adjusted according to the configuration of the sector (30) and the maximum radial occupancy of the laminate surface (13) defined by the sector (30) itself.
8. The device according to claim 7, wherein: For each linear actuator (31), said second restraining means (36) comprises a free end head (38) of the corresponding rod (34) releasably coupled to an engagement seat (37) of the corresponding sector (30).
9. Apparatus according to any one of the preceding claims, wherein: Each head (14, 15) is mounted on a guide column (22) which allows adjustment of the height.
10. The device according to claim 9, wherein: The guide uprights (22) protrude downwards from each head (14, 15) to define a respective support foot (23) of the support frame (11), and wherein the longitudinal connection means (16) are provided with wheels (25) to enable the device (10) to move after the heads (14, 15) have slid on the respective guide uprights (22) until the wheels (25) themselves come into contact with the floor surface and simultaneously make the support foot (23) disappear.
11. Apparatus according to any one of the preceding claims, wherein: The longitudinal connection device comprises at least one pair of longitudinal beams (16) extending between the heads (14, 15) and having an adjustable length.
12. Apparatus according to any one of the preceding claims, wherein: The central shaft (26') includes: a base module (26a'); and one or more auxiliary modules (26b'), wherein the one or more auxiliary modules (26b') are optionally axially connected to one or both of the ends of the base module (26a'), or connected to the already assembled auxiliary module (26b') itself to increase the axial length of the central shaft (26') itself.
13. A method for manufacturing a structural element (1) of composite material, said method being carried out by means of a device (1) according to any one of the preceding claims, said structural element (1) having a longitudinal axis (A) and an axial cavity (2), said method comprising the following steps: (a) connecting the sector (30) to the linear actuator (31) and arranging the sector (30) itself in the retracted position (26, 26') on the central axis (26); (b) mounting a laminating mandrel (12) with sectors (30) in a retracted position on said support frame (11); (c) moving the sector (30) into the extended lamination position by means of a linear actuator (31); (d) connecting said sector (30) in the extended lamination position to said movable part (18) of said head (14, 15) by means of said first restraining means (35); (e) releasing the second restraining means (36) to disconnect the linear actuator (31) from the sector (30); (f) retracting the linear actuator (31) towards the central axis (26, 26'); (g) extracting the central shaft (26, 26') with the retracted linear actuator (31) from the support frame (11); (h) laminating the lamination surface (13) of the sector (30) with an uncured or pre-cured composite material; (i) conveying the support frame (11) and the sectors (30) attached to the support frame (11) together with the laminated composite material to an autoclave to perform a curing cycle; (1) removing the components of step (1) from the autoclave; (m) reinserting the central shaft (26, 26') with the linear actuator (31) into the sector (30) and connecting the linear actuator (31) itself to the sector (30) by means of the second restraining means (36); (n) attaching the cured structural element (1) to the head (14, 15); (o) retracting said sector (30) to said retracted position on said central axis (26, 26') by means of said linear actuator (31) and with said second restraining means (36) activated; as well as (p) Extracting the laminating mandrel (12) with the sectors (30) in the retracted position from the cured structural element (1) and the supporting frame (11).
14. The method according to claim 13, wherein: Said step (n) is performed by moving said clamping member (40) to an operating position in which said clamping member (40) holds the opposite end edges of the curing structure (1) so as to fix said end edges to the heads (14, 15).