Process for manufacturing structural components in composite materials stiffened with at least one stringer.

Abstract

A process for manufacturing a structural component (1, 1', 1'', 1''', 1'''') made of a composite material comprising a skin (2) and at least one stiffening stringer (3, 3', 3'', 3''', 3'''') rigidly and integrally applied to one face (2a) of the skin (2), the process comprising: a) providing a longitudinal axis (A) and at least one stiffening stringer (3, 3', 3'', 3''', 3'''') extending parallel to the longitudinal axis (A) and along a resting surface (S) which may be flat or a surface of revolution; a) placing on a tool (12, 12', 12'', 12'''') a plurality of first layers (4, 4a', 4b', 4'', 4''', 4a'''', 4b'''', 4c'''') of uncured or pre-cured composite material forming a stringer (3, 3', 3'', 3''', 3'''', 3'''') having raised portions (7, 7', 7'', 7''', 7'''') protruding from a flange (8); and b) placing on a tool (12, 12', 12'', 12'''') a plurality of first layers (4, 4a', 4b', 4'', 4''', 4a'''', 4b'''', 4c'''') of uncured or pre-cured composite material forming said skin (2). c) placing a plurality of second layers of material on the tool (12, 12', 12'', 12''', 12''''); c) bonding together the surface (2a) of the skin (2) parallel to the resting surface (S) and the flanges (8) of the stringers (3, 3', 3'', 3''', 3'''', 3''''); and d) compressing the layers together and optionally curing uncured material to solidify the skin (2) to the stringers (3, 3', 3'', 3''', 3'''', 3''''). e) applying a predetermined temperature and pressure to the assembly thus formed so as to bond them together; and e) performing a cutting operation on the free side edges (13) of said flanges (8) obliquely to said resting surface and so that the cut layers (4, 4a', 4b', 4'', 4''', 4a'''', 4b'''') of said flanges (8) have, in a subsequent step c), an increasing extension along said resting surface towards the skin (2) itself.

Description

Technical Field

[0001] Cross - reference to related applications This patent application claims priority from Italian Patent Application No. 102020000018136, filed on July 27, 2020, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a process for manufacturing structural components in composite materials stiffened with at least one stringer.

[0003] In particular, this description expressly refers, without losing the general applicability thereof herein, to the manufacture of aircraft fuselages, wings, parts thereof or other structural parts.

Background Art

[0004] Structural components used in aviation, such as fuselages, wings and parts thereof, are known to be made of composite materials. The use of this material is driven by the need to reduce the total weight of the aircraft and to eliminate or minimize corrosion problems in the aircraft.

[0005] The composite materials used in the most common solutions consist of fiber materials, for example carbon fibers pre - impregnated with an epoxy, BMI or some other uncured or pre - cured material. The above materials are deposited in a mold and then processed under temperature and pressure. In other methods, dry fibers impregnated with a normally flowing resin are used according to well - known processes (for example, by a method known as "resin transfer molding" or RTM).

[0006] Typically, structural components of the above type, such as fuselages, wings or parts thereof, are also made of composite materials and are manufactured by joining a plurality of stiffening stringers and a composite skin, which are usually arranged parallel to a predetermined direction in which the above - mentioned structural components extend.

[0007] In particular, each stringer is usually, One or two longitudinal and transverse flanges suitable for bonding to the skin, A raised portion of a predetermined shape that protrudes laterally from the flange, It is defined by the longitudinal contour of the thin wall, including [the element].

[0008] The most commonly used stringers in the industry have Omega, T, L, J, or Z cross-sections.

[0009] To manufacture leather, multiple layers of the above-mentioned uncured composite material are laminated together.

[0010] Similarly, to manufacture a stringer, multiple layers of uncured composite material are placed on a forming tool of the appropriate shape.

[0011] Once the skin and stringer are manufactured, the stringer is brought into contact with the skin and joined to the skin at their respective flanges.

[0012] In this first embodiment, the assembly thus formed then undergoes a co-curing process in an autoclave by applying high pressure and high temperature to cure the composite material, compress the above layers together, and bond the stringer to the skin.

[0013] In practice, each stringa is firmly and integrally applied to one surface of the skin, the non-exclusive but usually the surface that defines the inner wall of the skin, i.e., the surface used facing the inside of the fuselage or wing.

[0014] Structural components are manufactured in this way.

[0015] In another embodiment, the stringer can be pre-cured after formation and then bonded to the skin using a structural adhesive. The thus formed assembly is placed in an autoclave and subjected to high pressure and high temperature to cure the new composite material, compress the different layers together, and bond the stringer to the skin. This process is commonly referred to in the industry as "cobonding."

[0016] Cobonding can also be achieved by pre-curing only the skin and then bonding it to the uncured stringer with a structural adhesive.

[0017] In a further embodiment, both the skin and the stringer can be pre-cured and then joined with a structural adhesive. This process is commonly referred to in the industry as "bonding" and can be performed in an autoclave or at cold temperatures.

[0018] Skin and strings can also be joined in different ways.

[0019] The first mode, known as "internal mold line" or IML, often involves the use of a hardening tool called a "mandrel," whose external shape defines the internal surface of the fuselage or wing section being manufactured. In practice, the mandrel has longitudinal cavities, each capable of housing a stiffening stringer.

[0020] Once the stringer is placed in the aforementioned cavity of the mandrel, depending on the shape of the stringer itself, it may be necessary to insert different types of inserts, known in the industry as "bladder" and "noodle," into the various cavities that can be formed after the stringer is placed on the mandrel. These inserts are designed to hold the various components in place and prevent them from being crushed by the high pressure when passing through an autoclave.

[0021] At this point, the assembly consisting of the mandrel, stringer and insert is covered with the relevant part of the skin which will form the outer surface of the aforementioned part of the fuselage or wing. If the stringer or the skin, or both, are pre-cured, a layer of structural adhesive is placed between the skin and the stringer.

[0022] Thus, the mandrel defines the innermost component in the resulting assembly.

[0023] At this point, the entire assembly is subjected to a co-curing, co-bonding or bonding operation as defined above, during which the stringer is firmly bonded and joined onto the skin.

[0024] During this operation, the bladder, made of an elastically deformable material and which can be either hollow or solid inside, expands to counteract the pressure applied to the outside of the assembly during the autoclave operation. More precisely, in the case of a hollow bladder, its inside is locked by an opening towards the inside of the autoclave so that both the outside of the assembly and any cavities in the stringer are subject to the same pressure. In the case of a solid bladder, the bladder is made of a material which expands with the increase in temperature.

[0025] Instead of a hollow bladder, a tubular bag can be used, the inside of which is locked to the inside of the autoclave.

[0026] The noodle continues to be integrated into the structure while the bladder is extracted at the end of the curing stage.

[0027] A second mode, known as the "outer mold line" or OML, involves the use of an "external" mandrel and the process is similar to the IML, except that the mandrel surrounds and supports the outer surface of the skin.

[0028] The step of trimming the longitudinal side edges of the flange of the stiffening stringer, which is carried out while the stringer is being formed on the forming tool, is also known in the industry.

[0029] While the aforementioned edges are being cut, it is known in the industry to cut these edges at 90° with respect to the support plane that supports the stringer, and the cutting is defined by a forming tool. Since the support plane is usually a horizontal plane and the cutting is performed from top to bottom, this type of cutting is the easiest to perform.

[0030] However, when the stringer is joined to the skin during co-curing, co-bonding or bonding operations, a 90° cut of the edge of the stringer leads to a rather significant surface discontinuity with respect to the inner surface of the skin, and thus, the transfer of operating loads from the stringer to the skin and vice versa is not optimal and can be improved.

[0031] At the same time, the fibers at the cut edge are exposed, increasing the risk of moisture penetrating the layer that forms the flange of the stringer and / or the finished component where the layer is peeling off.

[0032] Patent documents 1 is , claim 1 and 4 discloses a process for manufacturing a structural component made of a composite material as defined in the preamble of claim 1.

Prior art documents

Patent documents

[0033]

Patent Document 1

Summary of the invention

Problems to be solved by the invention

[0034] The object of the present invention is to disclose a process for manufacturing a structural component made of a composite material stiffened with at least one stringer, which is reliable, cost-limited, and capable of solving at least one of the problems identified above arising from the known types of processes described above. [Means for solving the problem]

[0035] According to the present invention, this objective is as stated in claim 1 or 4 This is achieved by a process for manufacturing a structural component made of a stiffening composite material having at least one stringer as described above.

[0036] For the purpose of better understanding the present invention, several preferred non-limiting embodiments are described below purely as examples and with the help of the accompanying drawings. [Brief explanation of the drawing]

[0037] [Figure 1] This is a perspective view of a structural component made of composite materials, particularly a composite panel defining a portion of an aircraft fuselage manufactured by the manufacturing process disclosed in this invention. [Figure 2] This is an enlarged cross-sectional view of a stiffening stringer of a structural component shown in Figure 1, on a forming tool, with the part removed for clarity, while the stringer is being formed. [Figure 3] Figure 2 shows an enlarged cross-sectional view of the stiffening stringer in the subsequent working conditions, with parts removed for clarity. [Figure 4] Figure 3 shows an enlarged cross-sectional view of the stiffening stringer in the subsequent working conditions, with parts removed for clarity. [Figure 5] Figure 1 shows a cross-sectional view of the structural component on the curing tool while the component is curing. [Figure 6] This figure shows possible variations of the steps shown, similar to Figure 5. [Figure 7] This is a cross-sectional view of a curing tool used in a step of a manufacturing process described in an alternative embodiment of the present invention. [Figure 8]This is a cross-sectional view of the structural component shown in Figure 1 on the curing tool shown in Figures 5 and 6 during the curing stage, as described in one embodiment of an alternative manufacturing process disclosed by the present invention. [Figure 9] This figure shows possible variations of the steps shown, similar to Figure 8. [Figure 10] These are cross-sectional views of different types of structural components on each curing tool during the corresponding curing step, as described in each further alternative embodiment of the manufacturing process disclosed by the present invention. [Figure 11] These are cross-sectional views of different types of structural components on each curing tool during the corresponding curing step, as described in each further alternative embodiment of the manufacturing process disclosed by the present invention. [Figure 12] These are cross-sectional views of different types of structural components on each curing tool during the corresponding curing step, as described in each further alternative embodiment of the manufacturing process disclosed by the present invention. [Figure 13] These are cross-sectional views of different types of structural components on each curing tool during the corresponding curing step, as described in each further alternative embodiment of the manufacturing process disclosed by the present invention. [Figure 14A] This is a diagram showing enlarged versions of Figures 10 through 13. [Figure 14B] This figure shows the detailed possible deformations shown in Figure 14A. [Modes for carrying out the invention]

[0038] Figure 1 shows an overall first example of a structural component made from a composite material manufactured by the process disclosed in the present invention.

[0039] This description will, in particular, expressly refer to structural components used in aviation, such as aircraft fuselages, wings or parts of fuselages or wings, and processes for manufacturing such structural components, without losing the general applicability of this specification.

[0040] According to preferred embodiments described and illustrated herein, a structural component 1 is defined by a panel intended to form part of an aircraft fuselage, the panel comprising a composite skin 2 and a series of cavities having closed sections, longitudinal stiffening stringers 3 configured to stiffen the panel.

[0041] Each stringer 3 has a longitudinal extension that is significantly larger than the extensions in the other two directions perpendicular to the longitudinal direction.

[0042] In the specific cases shown herein, the aforementioned longitudinal extension of the stringer 3 is also parallel in use to the longitudinal extension axis of the fuselage, which is at least partially formed by the structural component 1.

[0043] According to possible alternatives not shown, the stringa 3 can also be attached to the skin 2 such that its longitudinal extension is lateral to or perpendicular to the longitudinal extension axis of the fuselage.

[0044] The use of composite structural components in the aircraft industry is driven by the need to reduce the overall weight of the aircraft and to eliminate or minimize corrosion problems in the aircraft.

[0045] In one embodiment, the composite material used is a fibrous material, such as carbon fiber pre-impregnated with epoxy, BMI, or other uncured or pre-cured material. The material is deposited in a mold and then treated under temperature and pressure. In other methods, dry fibers, usually impregnated with a fluid resin, are used according to a well-known process (e.g., a method known as "resin transfer molding" or RTM).

[0046] The solutions shown in Figures 1 to 9 relate to a process for manufacturing structural component 1, which is obtained by firmly and integrally applying the stringers 3 to the skin 2 such that each stringer 3 forms a closed contour cavity together with the skin 2.

[0047] In particular, this description explicitly refers to the manufacture of a single panel defining a portion of the fuselage described above, without losing the general applicability of this specification.

[0048] More specifically, for the sake of simplification, we will assume that such panels are flat or substantially flat, i.e., they extend along a flat or substantially flat surface. However, the structural and functional features and steps of the procedure should be considered equally applicable to panels extending along surfaces with curved or rotating layouts, such as substantially parabolic surfaces, arched surfaces, or again, along (substantially) cylindrical or tapered surfaces.

[0049] In the latter case, skin 2 will have a (substantially) cylindrical or tapered shape (not shown) and will provide a central longitudinal axis. Stringers 3 will be positioned along their respective longitudinal axes parallel to the central axis of skin 2.

[0050] Structural component 1 can also be defined by a barrel intended to form a ring-shaped portion of the fuselage.

[0051] Furthermore, this description explicitly refers to a type of manufacturing process known as "internal mold line" or IML, which is well known in itself and will not be described in detail, without losing the general applicability of this specification.

[0052] However, if structural components are manufactured according to a type of process known as "outer mold line" or OML (not shown), which is also well known in itself and will not be described in detail, the process steps are equally applicable once the necessary modifications are made.

[0053] Referring to Figure 2, each stringer 3 is preferably fabricated by placing multiple layers 4 of uncured composite material on a molding portion 5 of a tool, in particular a forming tool 6 specially configured to form the stringer 3.

[0054] In particular, each stringer 3 has a longitudinal axis A and includes two lateral flanges 8 that are parallel to each axis A and extend along a single mounting surface S, and a raised portion 7 located in the center between the flanges 8, projecting toward the latter and having a concave shape on one side.

[0055] As identified above, the non-limiting examples described herein disclose a flat or substantially flat mounting surface S. In an alternative embodiment not shown herein, the mounting surface S may be curved, i.e., it may be a surface of rotation obtained by rotating the curve around an axis parallel to the axis A of the stringer 3 during inspection.

[0056] Therefore, in order to form each stringer 3, the manufacturing process of the structural component 1 includes the step of placing multiple layers 4 of uncured composite material on the molding portion 5 of a tool, which is a forming tool 6 in the example above, in order to form the stringers 3.

[0057] According to this preferred non-limiting embodiment, the stringer 3 has an omega-shaped cross-section.

[0058] Alternatively, the stringer 3, intended to create a closed cavity section with skin 2, can have different cross-sectional shapes, such as arcs, semicircles, rectangles, polygons, semi-ellipses, semi-ovals, etc.

[0059] To form skin 2, the process for manufacturing structural component 1 includes the step of laminating multiple layers (not shown) of uncured composite material.

[0060] This type of lamination is usually performed directly on the curing tool, which is described below.

[0061] To produce a panel defining the structural component 1, the manufacturing process further includes the step of bringing a surface 2a of the skin 2 parallel to the mounting surface S, and therefore flat in a specific example, the flange 8 of each stringer 3, into contact with each other, so as to form a closed contour cavity 10 (Figures 1 and 5) between the raised portion 7 of each stringer 3 and the skin 2 itself.

[0062] Furthermore, as shown above, the stringer 3 is positioned parallel to the longitudinal extension of the aircraft fuselage.

[0063] According to this preferred embodiment, the step of bringing the skin 2 and stringer 3 into contact with each other is performed by placing each pre-formed stringer 3 and skin 2 on a separate, special curing tool 12 (Figure 5), which is separate from the forming tool 6 used to produce the stringer 3.

[0064] In particular, the curing tool 12 is defined by a body (commonly known as a “mandrel”) that includes walls presenting a plurality of longitudinally molded slots or grooves 15 (only one of which is shown in Figure 5) configured to extend along the mounting surface S, bring the skin 2 and the stringer 3 into contact with each other, and receive the pre-formed stringer 3 during the same step, and before any steps supporting them in subsequent curing steps or operations, as will be better described below.

[0065] In the preferred embodiments described and illustrated herein, the curing tool 12 is flat because the mounting surface is flat.

[0066] In an alternative embodiment not shown, the curing tool 12 may also be defined by a curved, (substantially) cylindrical, or tapered body, depending on the shape of the mounting surface.

[0067] Conveniently, the manufacturing process further includes, after the step of forming the stringers 3 and before the step of bringing the skin 2 and the stringers 3 into contact with each other, a longitudinal insert 11 (Figure 5), commonly known as a "bladder," placed within the raised portion 7 of each stringer 3, so that when the step of bringing the skin 2 and the stringers 3 into contact with each other is completed, the insert 11 itself is fully housed within the cavity 10.

[0068] In particular, the insert 11 is made of an elastically deformable material and can expand while the structural component 1 is subsequently co-cured to maintain the cavity 10, as will be described in more detail below.

[0069] More specifically, the step of positioning the insert 11 is performed when the stringer 3 is positioned within each molding slot 15 on the curing tool 12.

[0070] After the insert 11 is in place, additional inserts 25, commonly known as "noodles," are placed at the corners between them and the skin 2. These "noodles" act as fillers and are made of uncured composite material.

[0071] The aforementioned co-curing process involves applying high pressure and high temperature (approximately 6 bar and 180°C) to the assembly consisting of skin 2, stringer 3, inserts 11 and 25, and curing tool 12, in order to cure the composite material and compress the aforementioned layers between them to bond stringer 3, insert 25, and skin 2, in particular to apply stringer 3 to the surface 2a of skin 2 in a firm and integral manner.

[0072] Therefore, the manufacturing process includes the step of applying high temperature and high pressure to the outside of the assembly and to the inside of the cavity 10 so as to cure the composite material and compress the layers together while maintaining the cavity 10.

[0073] In this regard, the manufacturing process includes, following the step of bringing the skin 2 and the stringer 3 into contact with each other, and during the step of applying temperature and pressure, the step of expanding each insert 11 against the boundary wall of its respective cavity 10 in order to maintain the cavity 10 during the curing process.

[0074] In particular, since each insert 11 is defined by an elastically deformable cavity body in the example described above, the expansion step is carried out by applying pressure to the inside of the insert 11 itself, and by applying the same pressure that is applied to the outside of the assembly, especially during the curing step.

[0075] More specifically, each insert 11 is provided with a valve connecting the inside and outside of the insert 11 in a manner not described in known details, so that during the curing step, the inside of the insert 11 is exposed to the same temperature and pressure conditions as the curing environment. Thus, possible deformation of the skin 2 toward the cavity 10 caused by the high pressure the structural component 1 experiences during the co-curing process is avoided, and the cavity 10 itself is thus maintained.

[0076] According to an alternative embodiment not shown, the insert 11 can be defined by a solid body made of an elastically deformable, temperature-sensitive material, particularly a thermally expandable material.

[0077] Therefore, in such cases, the expansion step is performed simply by exposing the insert 11 to the curing temperature, which in turn causes it to be pressed against the walls that divide the cavity 10.

[0078] According to an alternative embodiment not shown, the insert 11 can also be defined by a simple tubular bag on which the same pressure as the curing environment is applied internally.

[0079] At the end of the co-curing process, the resulting panel is separated from the curing tool 12 and the insert 11 is removed.

[0080] Instead of co-curing, skin 2 and stringer 3 can also be joined by co-bonding or bonding.

[0081] In the first case (cobonding), the stringer 3 (or skin 2) can be cured and then bonded to the uncured skin 2 (or uncured stringer 3) using a structural adhesive. The assembly thus formed is then placed in an autoclave and subjected to high pressure and high temperature to cure the new composite material and compress the different layers to bond the stringer 3 to the skin 2.

[0082] In the second case (bonding), both skin 2 and stringer 3 can be pre-cured and then joined with structural adhesive. This can be done by either autoclave bonding or cold bonding.

[0083] A trimming step of the free end side edge 13 of each stringer 3 is also known in the industry, in which each side edge 13 is defined by the free end of each flange 8 of the stringer 3, which is parallel to axis A, spaced apart from the raised portion 7, and extends laterally with respect to the mounting surface S.

[0084] In particular, it is known that a 90° cut of the side edge 13 is performed with respect to the support plane 14 that supports the stringer 3 during the cutting operation, and therefore with respect to the mounting surface S of the flange 8.

[0085] In the example described, the support plane 14 is separated from the molding portion 5 by the flat upper surface of the forming tool 6 adjacent to it.

[0086] figureReferring to 3, the process for manufacturing the structural component 1 includes the step of cutting the side edge 13 of the free end of the flange 8 obliquely to the mounting surface S, after the step of placing a plurality of layers 4 of the uncured composite material onto the molding portion 5 of the forming tool 6, and before bringing the skin 2 and the stringer 3 into contact with each other, wherein the mounting surface S is the surface on which the flange 8 extends such that the cut layers 4 of the flange 8 present an extending length that is along or parallel to the mounting surface S itself and increases as it progresses toward the skin 2 during the process of the subsequent steps of bringing the skin 2 and the stringer 3 into contact with each other.

[0087] In other words, as shown in Figure 3, the side edges 13 are cut obliquely with respect to the mounting surface S, which is flat in the case shown above, so that each cut side edge 13 defines an acute angle α with respect to the surface of each flange 8 placed on the forming tool 6, that is, with respect to the lower surface of each flange 8 as shown in Figure 3.

[0088] As shown in Figure 5, during the subsequent step of bringing the skin 2 and the stringer 3 into contact with each other, the cut flange 8 has an extended length that increases toward the surface 2a of the skin 2 when measured along the mounting surface S.

[0089] In practice, each flange 8 has a substantially semi-trapezoidal profile in a cross-section perpendicular to the axis A of each stringer 3, with its oblique side defined by its respective cut edge 13, and its main base is intended to touch the surface 2a of the skin 2.

[0090] Book solutionThe specific cutting configuration of the side edge 13 allows for the avoidance of discontinuities in the emphasized surface of the stringer 3 relative to the surface 2a of the skin 2 when the parts are joined together integrally. Conversely, such shear geometry results in a smoother connection between the flange 8 of each stringer 3 and the skin 2, and also improves the stress distribution in the joint region between the stringer 3 and the skin 2. In particular, the structural load during use is better distributed from the stringer 3 to the skin 2 and vice versa.

[0091] Furthermore, the stringer 3 thus obtained is easier to handle and to insert / extract into the molding cavity 15 of the hardening tool 12, in particular, which terminates at its opposing lateral ends with obtuse-angled chamfers having the same inclination as the side edges 13. As a result, the molding cavity 15 can present a simple shape without sharp chamfers and surface discontinuities.

[0092] According to this preferred non-limiting embodiment, the step of cutting the side edge 13 is performed when the associated stringer 3 is positioned on the forming tool 6.

[0093] As shown in Figure 5, the manufacturing process includes the step of placing each stringer 3 into the molded cavity of the tool, in particular the molded cavity 15 of the curing tool 12, which is molded to accommodate the formed and cut stringers 3, after each stringer 3 has been formed and its lateral edge 13 has been cut, and before the skin 2 and the stringer 3 come into contact with each other.

[0094] In detail, each molded cavity 15 has an outer contour, i.e., a wall that demarcates the cavity, which follows, i.e., the contour of the formed and cut stringer 3 on the opposite side from the surface 2a of the skin 2, i.e., follows it.

[0095] In practice, each molded cavity 15 is specially molded to accommodate a stringer 3 having already cut side edges 13.

[0096] As identified above, this solution Due to the specific shape of the flange 8 as disclosed, the contour of the molded cavity 15 is fairly simple, without sharp chamfers or surface discontinuities.

[0097] Advantageously, the manufacturing process also includes the step of coating the cut layer 4, i.e., the side edge 13 of the cut flange 8, with a composite material coating.

[0098] Such composite coatings are components or essential parts of the final structural component 1 at the end of the manufacturing process described herein.

[0099] In particular, as shown in Figure 4, the manufacturing process includes a step of laminating an additional layer 16 of composite material that forms the associated stringer 3, applied to the opposite side of the stringer 3 to the side intended to be applied to the surface 2a of the skin 2, after each stringer 3 has been formed and its side edges 13 have been cut, and before the skin 2 and the stringer 3 are brought into contact with each other. More precisely, the additional layer 16 defines the outermost layer of the stringer 3, i.e., the layer that is located on the "convex" side of the stringer 3.

[0100] The further layer 16 has opposing lateral end flaps 17 that project relative to the cut side edge 13 of the flange 8. The flaps 17 thus define the composite material coating on the side edge 13 of the cut layer 4.

[0101] Therefore, the step of covering the side edges 13 is performed by folding the flaps 17 over each of the cut side edges 13 to cover them and sealing them on the outside.

[0102] More specifically, according to the solution shown in Figure 5, the first portion 18 of the flap 17 covers the cut side edge 13 of each wing 8 during the folding of the flap 17 of the further layer 16, and the second portion 19 still protrudes from the cut side edge 13 itself and is folded over each flange 8 so as to be interposed between the skin 2 and the stringer 3 during the step of bringing the skin 2 and the stringer 3 into contact with each other.

[0103] In practice, the flaps 17 fold substantially into a "C" shape around the cut side edges 13 of the flange 8 so as to cover the layers 4 by sealing them from the outside.

[0104] Alternatively, according to the solution shown in Figure 6, the second portion 19 of the flap 17 is folded to interpose between the skin 2 and the curing tool 12 while the skin 2 and the stringer 3 are in contact with each other, i.e., the flap 17 of the additional layer 16 is folded to the opposite side of each flange 8 while it is on the curing tool 12.

[0105] In practice, the flaps 17 fold into a substantially "Z" shape around the cut side edges 13 of the flange 8 so as to cover the layers 4 by sealing them from the outside.

[0106] The fibers that remain uncovered as a result of cutting the side edges 13 are thus protected. This reduces or eliminates the risk of moisture or other fluids entering between layers 4, as well as the risk of structural delamination of the completed component 1.

[0107] Referring to Figures 7 to 9, the steps of the aforementioned manufacturing process for structural component 1 are illustrated and described below in an alternative embodiment of the present invention.

[0108] In particular, according to this alternative embodiment of the manufacturing process, the step of covering the side edges 13 of the flange 8 is performed by applying patch elements 20 made of uncured composite material to the cut side edges 13 to cover them and then sealing them from the outside. In this case, the patch elements 20 define the composite material coating on the side edges 13 of the cut layer 4.

[0109] In particular, the patch element 20 is defined by a longitudinal insert of a thin wall of uncured composite material.

[0110] Preferably, as shown in Figure 7, the patch element 20 is positioned in the molding cavity 15 of the curing tool 12, in particular in the chamfered portion of the cavity which will accommodate and support the cut side edge 13 of the flange 8.

[0111] Therefore, the patch element 20 is applied to the side of the associated stringa 3 that is opposite to the side of skin 2a that it was intended to be applied to.

[0112] In particular, the patch element 20 is positioned to protrude from the cut side edge 13 of the flange 8.

[0113] As seen in the solution in Figure 8, the first portion 21 of the patch element 20 covering the cut edge 13 and the second portion 22 that still protrudes from the cut edge 13 itself are folded over the respective flanges 8 while the patch element 20 is applied to the cut edge 13 so as to be interposed between the skin 2 and the respective stringers 3 while the skin 2 and the stringers 3 are in contact.

[0114] Furthermore, each patch element 20 includes a third portion 23 folded over the respective flange 8 on the side opposite to the respective second portion 22, and in fact, when the stringer 3 is placed on the curing tool 12, the third portion 23 is interposed between each stringer 3 and the molding cavity 15 of the curing tool 12.

[0115] In practice, the patch elements 20 are folded into a substantially "C" shape around the cut side edges 13 of the flange 8 so as to cover them by sealing layer 4 on the outside.

[0116] Alternatively, according to the solution shown in Figure 9, the second portion 22 is folded so that it interposes between the skin 2 and the curing tool 12 while the skin 2 and the stringer 3 are in contact with each other, i.e., the patch element 20 is folded to the opposite side of each flange 8 while it is on the curing tool 12.

[0117] In practice, the patch elements 20 are folded into a substantially "Z" shape around the cut side edges 13 of the flange 8 so as to cover them by sealing layer 4 on the outside.

[0118] Figures 10 to 13 show cross-sectional views of other types of structural components during the co-curing step, denoted as 1', 1'', 1''', and 1'''' respectively, which can be obtained by the process disclosed in the present invention.

[0119] Structural components 1', 1'', 1'''', 1'''' and their manufacturing processes are described below only if they differ from each other and from structural component 1, as well as from the manufacturing methods described above. Parts that are equal to or equivalent to parts already described are indicated by the same reference numbers.

[0120] As already seen in relation to structural component 1, it should also be noted that the final co-curing of structural components 1', 1'', 1'''', and 1'''' can also be replaced by autoclave co-bonding or cold co-bonding or a combination thereof.

[0121] With respect to Figure 10, structural component 1' includes the same skin 2 as described above and a stringer 3' whose shape is different from that of stringer 3.

[0122] More precisely, the stringer 3' has a longitudinal axis A and a cross-sectional area that is substantially T-shaped and spans the longitudinal axis A. The stringer 3' includes two transverse flanges 8 identical to the flange 8 of the stringer 3, and a raised portion 7' ​​having a thin, flat sheet that extends in a direction substantially perpendicular to the flanges 8 and the mounting surface S.

[0123] Stringa 3' is, Two sets of uncured L-shaped composite materials facing each other, each consisting of two straight sections perpendicular to each other at its base and back, the base and back joined by a common curved section and arranged side by side along each back, A third series of flat layers 4b' of uncured composite material defining the portion of flange 8 intended to contact skin 2, This is obtained by layering it onto a special forming tool (which is known in itself and is not shown in the illustration).

[0124] Next, one or more inserts 25', commonly known as "noodles," are inserted into the gaps created between layers 4b' and 4a' in the region where a common curved feature is located, and the curved feature acts as a filler, made of uncured composite material.

[0125] In this solution as well, the free end side edge 13 of the flange 8 is cut obliquely with respect to the mounting surface S so as to present an extended length that increases toward the skin 2, along or parallel to the mounting surface S itself, in the subsequent step of bringing the skin 2 and the stringer 3' into contact with each other.

[0126] The assembly formed by skin 2 and stringer 3' is placed on a hardening tool 12' having a housing for skin 2, in this case, an OML type, for example.

[0127] Advantageously, the side edges 13 of the flange 8 are covered and sealed on the outside by respective patch elements 20 made of thin-walled uncured composite material.

[0128] In particular, as can be seen in Figures 10 and 14A, while the patch element 20 is applied to the cut edge 13, the first portion 21 of the patch element 20 covers the cut edge 13, and while the skin 2 and the stringer 3' are in contact with each other, the second portion 22 protruding from one side of the edge 13 is folded over the skin 2, and the third portion 23 protruding from the opposite side of the cut edge 13 is folded over the respective flanges 8 on the side of the raised portion 7'.

[0129] In practice, the patch element 20 is folded into a substantially "Z" shape around the side edge 13 of the flange 8 so as to cover layers 4a' and 4b' by sealing them from the outside.

[0130] Alternatively, according to the solution shown in Figure 14B, the second portion 22 can be folded onto the respective flanges 8 at a position facing the third portion 23 during the folding of the patch element 20 so as to interpose between the skin 2 and the stringer 3' while they are in contact.

[0131] In practice, the patch element 20 is folded into a substantially C shape around the side edge 13 of the flange 8 so as to cover layers 4a' and 4b' by sealing them from the outside.

[0132] The free end side edge of the raised portion 7' ​​is also covered and sealed on the outside by the C patch element 30.

[0133] In this case, the co-curing process is carried out by sealing a vacuum bag 31 on a curing tool 12' that covers each stringer 3' externally.

[0134] According to one possible alternative embodiment not shown, and in analogy with those seen in the procedure described with respect to Figures 1 to 6, the outermost composite layers 4a' of the two L forming the stringer 3' may each have lateral end flaps projecting relative to the cut side edges 13 of the flanges 8, which are folded over them in a C or Z shape to cover and seal the side edges 13 themselves from the outside. Thus, the projecting flaps would be replaced by the patch elements 20.

[0135] As shown above, Stringer 3' (or Skin 2) can also be pre-cured, bonded to Skin 2 (or Stringer 3') with a layer of structural adhesive, and then autoclaved together with Skin 2 (or Stringer 3').

[0136] According to one further possible embodiment, both the stringer 3' and the skin 2 may be pre-cured individually, joined together using a structural adhesive, and then subjected to an autoclave or cold bonding process.

[0137] With respect to Figure 11, structural component 1'' includes the same skin 2 as described above, and stringer 3'' having a different shape from stringers 3 and 3'.

[0138] In particular, stringer 3'' has a longitudinal axis A and a cross-sectional area that is substantially L-shaped and spans the longitudinal axis A. Stringer 3'' includes a single transverse flange 8 which is identical to the corresponding flange 8 of stringers 3 and 3', and a raised portion 7'' having a thin, flat sheet that extends substantially in a direction perpendicular to the flange 8 and the mounting surface S of the flange.

[0139] More precisely, the raised portion 7'' is connected at one end to the other end of the flange 8 by a curved section 7a''.

[0140] The stringer 3'' is obtained by laminating a series of layers 4'' of uncured L-shaped composite material having the same course as the flange 8 and the raised portion 7'' onto a special molding tool (which is known in itself and not shown).

[0141] In this solution as well, the side edge 13 of the free end of the flange 8 is cut obliquely with respect to the mounting surface S so as to present an extended length that increases toward the skin 2, along or parallel to the mounting surface S itself, in the subsequent step of bringing the skin 2 and the stringer 3'' into contact with each other.

[0142] The assembly formed by skin 2 and stringer 3'' is placed on a hardening tool 12'' having a housing for skin 2, in this case, an OML type, for example.

[0143] In this case, the hardening tool 12'' also includes an auxiliary tool 12a'' having a hollow square with curved or rounded edges, which is positioned on the opposite side of the skin 2 from the hardening tool 12'' and receives the raised portion 7'' of the stringer 3'' with its own boundary wall 32.

[0144] One or more inserts 25'', commonly known as "noodles," are inserted into the gaps created between the skin 2, the auxiliary tool 12a'', and the stringer 3'' in the curved section 7a''. These inserts 25'' act as fillers and are made of uncured composite material.

[0145] Advantageously, the side edge 13 of flange 8 is covered and sealed on the outside by a patch element 20 (Figures 11, 14A and 14B) made of thin-walled uncured composite material, which is identical to the one used to cover the side edge 13 of flange 8 of stringer 3, 3' and folds in the exact same two modes shown above (Figures 14A and 14B).

[0146] Even in this case, the free end side edge of the raised portion 7'' is covered and sealed on the outside by the C patch 30.

[0147] In this case, the co-curing process is carried out by sealing a vacuum bag 31 that covers each stringer 3'' externally on the curing tool 12'' and auxiliary tool 12a''.

[0148] According to one possible alternative embodiment not shown, and in similarity to that seen in the process described in relation to Figures 1 to 6, the outermost composite material layer 4'' forming the stringer 3'' may also have lateral end flaps that project toward the associated cut side edges 13 of the flange 8 and are folded over them in a C or Z shape to cover the side edges 13 themselves and seal them outward. Thus, the projecting flaps would be replaced by patch elements 20.

[0149] As shown above, Stringer 3'' (or Skin 2) can also be pre-cured, bonded to Skin 2 (or Stringer 3'') by a layer of structural adhesive, and then subjected to autoclave co-bonding together with Skin 2 (or Stringer 3'').

[0150] In a further embodiment, both the stringer 3'' and the skin 2 may be pre-cured individually, joined together with a structural adhesive, and then subjected to an autoclave or cold bonding process.

[0151] With respect to Figure 12, structural component 1''' includes the same skin 2 as described above, and stringers 3''' having a different shape from stringers 3, 3' and 3''.

[0152] More precisely, the stringer 3''' has a longitudinal axis A and a cross section that crosses the longitudinal axis A, which is substantially Z-shaped. The stringer 3''' includes a single transverse flange 8 intended to be joined to a skin 2 which is identical to the flange 8 of the stringer 3'', and a raised portion 7''' of a thin sheet including a first section 7a''' that cantilevered from the flange 8 and substantially perpendicular to the flange 8 and the mounting surface S of the flange, and a second flange section 7b''' that extends from section 7a''' in the opposite direction from the flange 8 and is parallel to the flange 8.

[0153] In particular, section 7a''' has a first end connected to one end of flange 8 by a curved section 7c''' and a second opposing end connected to section 7b''' by another curved section 7d'''.

[0154] The stringer 3''' is fabricated by laminating a series of layers 4''' made of uncured Z-shaped composite material having the same course as the flange 8 and the raised portion 7''' onto a special molding tool (which is well known and not shown).

[0155] In this solution as well, the side edge 13 of the free end of the flange 8 is cut obliquely with respect to the mounting surface S so as to present an extended length that is along or parallel to the mounting surface S itself and increases toward the skin 2 in the subsequent step of bringing the skin 2 and the stringer 3''' into contact with each other.

[0156] The assembly formed by Skin 2 and Stringer 3'''' is placed on the same curing tool 12'' and auxiliary tool 12a'' used for Component 1''.

[0157] In this case, the boundary wall 32 of the auxiliary tool 12a'' is supported by section 7a''' of the raised portion 7''' of the stringer 3''', and another boundary wall 33 adjacent to and perpendicular to the boundary wall 32 is supported by section 7b'''. The curved section 7d''' of the raised portion 7''' of the stringer 3''' is instead positioned at the curved edge joining the boundary walls 32 and 33.

[0158] One or more inserts 25''', commonly known as “noodles,” which act as fillers and are made of uncured composite material, are inserted into the gap created between the skin 2, the auxiliary tool 12a'', and the stringer 3''' in the curved section 7c'' of the raised portion 7''''.

[0159] Advantageously, the side edges 13 of flange 8 are covered and sealed on the outside by patch elements 20 (Figures 12, 14A, and 14B) made of thin-walled uncured composite material, which are identical to those used to cover the side edges 13 of flange 8 of stringers 3, 3', and 3'' and fold in exactly the same two ways as seen above (Figures 14A and 14B).

[0160] Even in this case, the free end side edge of the raised section 7b''' of the raised portion 7'''' is covered and sealed on the outside by the C patch element 30.

[0161] As seen in relation to structural component 1'', the co-curing process is carried out by sealing a vacuum bag 31 covering each stringer 3'''' on the curing tool 12'' and auxiliary tool 12a''.

[0162] According to one possible alternative embodiment not shown, and in similarity to that seen in the process described with respect to Figures 1 to 6, the outermost composite material layer 4'''' forming the stringer 3'''' may also have a lateral end flap projecting toward the associated cut side edge 13 of the flange 8, which is folded over therein in a C or Z shape to cover and seal the side edge 13 outward. Thus, the projecting flap would be replaced by a patch element 20.

[0163] As shown above, Stringer 3''' (or Skin 2) can also be pre-cured, bonded to Skin 2 (or Stringer 3''') with a layer of structural adhesive, and then subjected to autoclave co-bonding together with Skin 2 (or Stringer 3''').

[0164] According to one further possible embodiment, both the stringer 3'' and the skin 2 may be pre-cured individually, joined together using a structural adhesive, and then subjected to an autoclave or cold bonding process.

[0165] With respect to Figure 13, structural component 1'''' includes the same skin 2 as described above, and stringers 3'''' having a different shape from stringers 3, 3', 3'' and 3''''.

[0166] More precisely, the stringer 3'''' has a longitudinal axis A and a cross section that crosses the longitudinal axis A in substantially J-shape. The stringer 3'''' includes a single transverse flange 8 intended to be joined to the skin 2 and identical to the flange 8 of the stringers 3'' and 3'''', and a raised, thin laminated portion 7'''' that cantilevered from the flange 8, including a first section 7a'''' substantially perpendicular to the flange 8 and the mounting surface S of the flange, and a second flanged section 7b'''' that is parallel to the flange 8 and extends symmetrically from section 7a'''' on both sides thereof.

[0167] In particular, section 7a'''' has a first end connected to one end of flange 8 by curved section 7c'''' and a second opposing end connected to section 7b'''' by section 7d'''', which has sections that are divided on both sides by their respective concave curved surfaces.

[0168] More precisely, section 7b'''' is divided by sections 7a'''' and 7d'''' into two segments 7b1'''' and 7b2'''', which extend from both sides of sections 7a'''' and 7d'''', with segment 7b1'''' facing flange 8, while segment 7b2'''' extends to the side of section 7a'''' opposite to segment 7b1''''.

[0169] Stringa 3'''' is, A first series of layers 4a'''' made of untreated Z-shaped composite material, positioned closer to skin 2 and having the same course as flange 8, sections 7a'''', 7c'''' and segment 7b2'''' of raised portion 7'''', A second series of C-shaped uncured composite material layers 4b'''' having the same course as flange 8, sections 7a'''', 7c'''' and segment 7b1'''' of raised portion 7'''', A series of flat layers 4c'''' of untreated composite material having the same course as the entire section 7b'''', superimposed on the corresponding portions of layers 4a'''' and 4b'''' that form segments 7b1'''' and 7b2'''', This is obtained by laminating it onto a special forming tool (well-known and not disclosed).

[0170] Next, one or more inserts 25'''', commonly known as “noodles,” which act as fillers and are made of uncured composite material, are inserted into the gaps between layer 4c'''' and layers 4a'''' and 4b'''' in the connecting region between sections 7a'''', 7b'''' and 7d''''.

[0171] In this solution as well, the free end side edge 13 of the flange 8 is cut obliquely with respect to the mounting surface S so as to present an extended length that increases toward the skin 2, along or parallel to the mounting surface S itself, in the subsequent step of bringing the skin 2 and the stringer 3'''' into contact with each other.

[0172] The assembly formed by skin 2 and stringer 3'''' is positioned on the hardening tool 12'''', which includes a first auxiliary tool 12a'''' having substantially the same shape as the hardening tool 12'' and similar to the auxiliary tool 12a'''', and a second auxiliary tool 12b'''' having a hollow rectangle with a curved or rounded edge, which is also positioned when used on the side of section 7a'''' of stringer 3'''' opposite to auxiliary tool 12a''''. Thus, section 7a'''' of stringer 3'''' remains interposed between auxiliary tools 12a'''' and auxiliary tool 12b'''', and furthermore, auxiliary tool 12b'''' cooperates with flange 8 through its own boundary wall 34, with segment 7b1'''' through its own boundary wall 35 parallel to and opposite boundary wall 34, and with section 7a'''' through its own boundary wall 36 interposed between them perpendicular to boundary walls 34 and 35.

[0173] One or more inserts 25'''', commonly known as “noodles,” which act as fillers and are made of uncured composite material, are inserted into the gap formed between the skin 2, the auxiliary tool 12a'''' and the stringer 3'''' in the curved section 7c'''' of the raised portion 7''''.

[0174] Advantageously, the side edges 13 of flange 8 are covered and sealed on the outside by patch elements 20 (Figures 13, 14A, and 14B) made of thin-walled uncured composite material, which are identical to those used to cover the side edges 13 of flange 8 of stringers 3, 3', 3'', and 3'''' and fold in exactly the same two modes as seen above (Figures 14A and 14B).

[0175] In this case as well, the opposing free end edges of the raised portion 7b'''' are covered and sealed on the outside by their respective C-shaped patch elements 30.

[0176] As seen in relation to structural components 1'', 1'''', the co-curing process is carried out by sealing vacuum bags 31 covering each stringer 3'''' externally on the curing tool 12'''' and on auxiliary tools 12a'''' and 12b''''.

[0177] According to one possible embodiment not shown, and in similarity to that seen in the process disclosed with respect to Figures 1 to 6, a layer 4b'''' made of composite material forming a layer of flange 8 opposite to that intended to work with skin 2 may also have a lateral end flap projecting toward the associated cut side edge 13 of flange 8, which is folded over therein in a C or Z shape to cover the side edge 13 and seal it outward. Thus, the projecting flap would replace the patch element 20.

[0178] As shown above, Stringer 3'''' (or Skin 2) can be pre-cured, bonded to Skin 2 (or Stringer 3'''') by a layer of structural adhesive, and then subjected to autoclave co-bonding together with Skin 2 (or Stringer 3'''').

[0179] According to one further possible embodiment, both the stringer 3'''' and the skin 2 may be pre-cured individually, joined together with a structural adhesive, and then subjected to an autoclave or cold bonding process.

[0180] Examining the characteristics of the manufacturing processes for the aforementioned structural components 1, 1', 1'', 1'''', and 1'''' reveals the advantages that can be achieved therein.

[0181] In particular, this manufacturing process makes it possible to obtain structural components 1, 1', 1'', 1'''', 1'''' without discontinuities in the surface, especially at the joints between stringers 3, 3', 3'', 3''', 3'''' and skin 2. In fact, a smoother connection is determined between the flange 8 of each stringer 3, 3', 3'', 3'''' and the skin 2, and the stress distribution at the joints between stringers 3, 3', 3'', 3'''' and skin 2 is also improved.

[0182] In particular, this result optimizes the transmission of operational load from Stringer 3, 3', 3'', 3'''', 3'''' to Skin 2 and vice versa.

[0183] Furthermore, in the case of Stringer 3, these facilitate handling and insertion / extraction of the hardening tool 12, particularly in the molded cavity 15 of the hardening tool 12. Thus, the molded cavity 15 can have a simple shape without sharp chamfers or surface discontinuities.

[0184] Finally, the presence of the additional layer 16 or patch element 20 protects the exposed fibers at the side edges 13 of the flange 8 or the edges of other parts of the stringers 3, 3', 3'', 3''', 3'''', reducing or eliminating the risk of moisture or other fluids used to penetrate, as well as the risk of structural delamination. In other words, in addition to being an integral or component of the final structural components 1, 1', 1'', 1''', 1'''', the additional layer 16 or patch element 20 defines a coating that protects the side edges 13 of the flange 8 or the edges of the stringers 3, 3', 3'', 3''', 3'''' from moisture.

[0185] It is clear that modifications and alterations can be made to the process for manufacturing the structural components 1, 1', 1'', 1'''', and 1'''' described and illustrated herein, without departing from the scope of protection defined by the claims.

[0186] In particular, the step of forming each stringer 3, 3', 3'', 3'''', 3'''' can also be performed while the stringers themselves are placed on the hardening tools 12, 12', 12'', 12''''.

[0187] Furthermore, the step of cutting the side edges 13 can also be performed directly when the stringers 3, 3', 3'', 3''', 3'''' are positioned on the hardening tools 12, 12', 12'', 12''''.

[0188] Thus, the entire process can also be performed using a single tool for forming and curing the components. [Explanation of Symbols]

[0189] 1. Structural Components 1' Structural Components 1'' Structural components 1''' Structural Components 1'''' Structural component 2 skins 2a side 3 Stringa 3' Stringa 3'' Stringer 3'' Stringa 3'''' Stringa 4 layers 4a' layer 4b' layer 4'' layer 4''' layer 4a'''' layer 4b'''' layer 4c'''' layer 5 Molded part 6. Shaping Tools 7 Raised area 7' raised area 7'' raised area 7a'' Curved section 7''' Raised area 7a'' Section 1 7b''' Second flange section 7c''' Curve section 7d''' Another curve section 7'''' Raised area 7a'''' Section 1 7b'''' Second flanged section 7c'''' Curved section 7d'''' Section 7b1'''' Segment 7b2'''' Segment 8 flanges 10 cavities 11 Inserts 12. Curing Tools 12' Curing Tool 12'' curing tool 12a'' Auxiliary Tools 12'''' Curing Tool 12a'''' First auxiliary tool 12b'''' Second auxiliary tool 13 Side edges 14 Support plane 15 groove 16. Further layers 17 Flap 18 Part 1 19 Part 2 20 patch elements 21 Part 1 22 Part 2 23. Part 3 25 Inserts 25' Insert 25'' Insert 25'' insert 25'''' Insert 30 C patch element 31 Vacuum Bags 32 Boundary wall 33 Another boundary wall 34 Boundary Wall 35 Boundary Wall 36 Boundary Wall

Claims

1. A process for manufacturing a structural component (1, 1', 1'', 1'''', 1'''') in a composite material comprising a skin (2) and at least one stiffening stringer (3, 3', 3'', 3'''', 3'''') applied integrally to the surface (2a) of the skin (2), wherein the process is: a) A step of arranging a plurality of first layers (4, 4a', 4b', 4'', 4'''', 4a'''', 4b'''', 4c'''') of uncured or precured composite material forming the stiffening stringers (3, 3', 3'', 3'''', 3'''') on a tool (12, 12', 12''''), wherein the stiffening stringers (3, 3', 3'', 3'''', 3'''') provide a longitudinal axis (A) and have raised portions (7, 7', 7'', 7'''', 7'''') protruding from at least one flange (8) that extends parallel to the longitudinal axis (A) and along a mounting surface (S) which is flat or a rotating surface, b) The step of placing a plurality of second layers of uncured or pre-cured composite material that form the skin (2) onto the tool (12, 12', 12'', 12''''), c) The step of bonding the surface (2a) of the skin (2) parallel to the aforementioned mounting surface (S) and the flange (8) of the stiffening stringer (3, 3', 3'', 3'''', 3'''') to each other, d) The step of applying a predetermined temperature and pressure to the resulting assembly so as to compress the plurality of first layers (4, 4a', 4b', 4'', 4''', 4a'''', 4b'''', 4c'''') and the plurality of second layers together, e) A step of performing a cutting operation on the free end side edge (13) of the flange (8) in a direction oblique to the mounting surface (S) described above and the layers (4, 4a', 4b', 4'', 4''', 4a'''', 4b'''') that form the flange (8) itself, and such that in the subsequent step c), the cut layers (4, 4a', 4b', 4'', 4''', 4a'''', 4b'''') of the flange (8) have an extended length that increases toward the skin (2) itself along the mounting surface (S), f) a step of covering at least the free end side edge (13) of the flange (8) with a composite material coating so as to seal the layers (4, 4a', 4b', 4'', 4''', 4a'''', 4b'''') that form the flange (8) cut in step e) on the outside, wherein the composite material coating defines the structure or integral portion of the structural component (1, 1', 1'', 1''', 1'''') at the end of the process, Includes, The process further comprises, after step e), step g) laminating at least further layers (16) of the composite material forming the stiffening stringer (3, 3', 3'', 3'''', 3'''') applied to the side of the stiffening stringer (3, 3', 3'', 3'''', 3'''' that is opposite to the side applied to the surface (2a) of the skin (2), wherein the further layers (16) have one or two lateral end flaps (17) projecting toward the cut free end side edges (13) of the flange (8), and step f) is performed by folding the lateral end flaps (17) of the further layers (16) toward each of the cut free end side edges (13) of the flange (8) to cover the free end side edges (13), thereby sealing the free end side edges (13) toward the outside and defining the coating of the composite material.

2. The process according to claim 1, wherein during the folding of the lateral end flaps (17) of the further layer (16), a first portion (18) of the lateral end flaps (17) or each of the lateral end flaps (17) covers the respective cut free end side edges (13) of the flange (8), and a second portion (19) that still protrudes from the cut free end side edges (13) itself is folded over the flange (8) in step c) so as to be interposed between the skin (2) and the stiffening stringers (3, 3', 3'', 3'''', 3'''').

3. The process according to claim 1, wherein during the folding of the lateral end flaps (17) of the further layer (16), a first portion (18) of the lateral end flaps (17) or each of the lateral end flaps (17) covers the respective cut free end side edges (13) of the flange (8), and a second portion (19) that still protrudes from the cut free end side edges (13) itself is folded back from the opposite portion of the flange (8) during step c) so as to be interposed between the skin (2) and the tool (12, 12', 12'', 12'''').

4. A process for manufacturing a structural component (1, 1', 1'', 1'''', 1'''') in a composite material comprising a skin (2) and at least one stiffening stringer (3, 3', 3'', 3'''', 3'''') applied integrally to the surface (2a) of the skin (2), wherein the process is: a) A step of arranging a plurality of first layers (4, 4a', 4b', 4'', 4'''', 4a'''', 4b'''', 4c'''') of uncured or precured composite material forming the stiffening stringers (3, 3', 3'', 3'''', 3'''') on a tool (12, 12', 12''''), wherein the stiffening stringers (3, 3', 3'', 3'''', 3'''') provide a longitudinal axis (A) and have raised portions (7, 7', 7'', 7'''', 7'''') protruding from at least one flange (8) that extends parallel to the longitudinal axis (A) and along a mounting surface (S) which is flat or a rotating surface, b) The step of placing a plurality of second layers of uncured or pre-cured composite material that form the skin (2) onto the tool (12, 12', 12'', 12''''), c) The step of bonding the surface (2a) of the skin (2) parallel to the aforementioned mounting surface (S) and the flange (8) of the stiffening stringer (3, 3', 3'', 3'''', 3'''') to each other, d) The step of applying a predetermined temperature and pressure to the resulting assembly so as to compress the plurality of first layers (4, 4a', 4b', 4'', 4''', 4a'''', 4b'''', 4c'''') and the plurality of second layers together, e) A step of performing a cutting operation on the free end side edge (13) of the flange (8) in a direction oblique to the mounting surface (S) described above and the layers (4, 4a', 4b', 4'', 4''', 4a'''', 4b'''') that form the flange (8) itself, and such that in the subsequent step c), the cut layers (4, 4a', 4b', 4'', 4''', 4a'''', 4b'''') of the flange (8) have an extended length that increases toward the skin (2) itself along the mounting surface (S), f) a step of covering at least the free end side edge (13) of the flange (8) with a composite material coating so as to seal the layers (4, 4a', 4b', 4'', 4''', 4a'''', 4b'''') that form the flange (8) cut in step e) on the outside, wherein the composite material coating defines the structure or integral portion of the structural component (1, 1', 1'', 1''', 1'''') at the end of the process, Includes, Step f) is performed by applying one or each of the patch elements (20) in the uncured composite material to the cut free end edge (13) of the flange (8) to cover the free end edge (13) and seal the free end edge (13) on the outside to define the coating of the composite material. A process characterized in that, during the application of the patch element (20) or each of the patch element (20) to the cut free end edge (13), a first portion (21) of the patch element (20) itself covers each of the cut free end edges (13) of the flange (8), and a second portion (22) that still protrudes from the cut free end edge (13) itself is folded onto the flange (8) in step c) so as to be interposed between the skin (2) and the stiffening stringers (3, 3', 3'', 3''', 3'''') or between the skin (2) and the tools (12, 12', 12'', 12'''').

5. The process according to any one of claims 1 to 4, wherein the stiffening stringers (3', 3'', 3'''', 3'''') have a T, L, Z, or J shaped contour in a cross-section with respect to the longitudinal axis (A).

6. The process according to any one of claims 1 to 4, wherein the raised portion (7) of the stiffening stringer (3) forms a concave shape on one side and is positioned in the center between the two lateral flanges (8) extending along the aforementioned mounting surface (S), and in step c), the skin (2) and the raised portion (7) of the stiffening stringer (3) form a closed-contour cavity (10).

7. After step a) and before step c), h) includes the step of positioning at least one longitudinally expandable insert (11) inside the raised portion (7) of the stiffening stringer (3) so that the longitudinally expandable insert (11) is fully housed within the cavity (10) defined in step c), The process according to claim 6, further comprising the step after step c) and during step d) i) inflating the longitudinally expandable insert (11) against the wall separating the cavity (10) to maintain the cavity (10).

8. The process according to claim 7, wherein step i) is performed by applying pressure to the inside of the longitudinally expandable insert (11).

9. The process according to claim 7, wherein step i) is performed by applying heat to the longitudinally expandable insert (11).

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