Method for manufacturing a part made of thermoplastic composite material
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ARIANEGRP SAS
- Filing Date
- 2025-12-08
- Publication Date
- 2026-07-30
Smart Images
Figure FR2025051138_30072026_PF_FP_ABST
Abstract
Description
Description Title of the invention: Method for manufacturing a part made of thermoplastic composite material Technical Field
[0001] The present presentation relates to a manufacturing process for a part made of thermoplastic matrix composite material using an automated fiber placement draping technique (“Automated Fiber Placement”; “AFP”). Previous technique
[0002] Composite materials offer a weight saving compared to metallic materials, which is of particular interest in aerospace and aeronautical applications with a view to improving performance.
[0003] The use of a thermoplastic composite can be considered for forming components intended for integration into a space launch vehicle, such as a shell or a tank. Automated fiber placement techniques are advantageous for reducing the production cost of composite parts. However, inventors have observed that the automated fiber placement of pre-impregnated layers of thermoplastic resin onto a mold at room temperature can lead to deformation of the stack as the thickness increases, with the deformation being more pronounced the thicker the part. These deformations are linked to the stresses created in the preform by the thermal gradient through the thickness during the draping process. These stresses tend to curve the part as the draping progresses and can lead to its detachment from the draping mold.
[0004] To counter this phenomenon, one could consider integrating a heating element into the draping mold to relieve stress in the preform during draping through continuous heating. However, this solution presents other problems in terms of maintaining the part's geometry due to the expansion of the heated mold, energy consumption, and operator safety, as they may have to work in an overheated environment. All these aspects limit the use of thermoplastic technology.
[0005] It is therefore desirable to have a manufacturing process for a part made of thermoplastic composite material that addresses all or some of the aforementioned disadvantages. Description of the invention
[0006] This presentation concerns a manufacturing process for a part made of thermoplastic composite material, the process comprising: - the deposition onto a support of a first set of stacked fibrous layers by automatic fiber placement, the fibrous layers being made of thermoplastic prepreg fibrous material, - the interruption of the deposition of the fibrous layers and the carrying out, while this deposition is interrupted, of a first relaxation, the first assembly being subjected, during the first relaxation, to a first heat treatment comprising a sweep of a surface of the first assembly, opposite the support, by a first local heating, of limited extent to a fraction of this surface, in relative motion with respect to this surface, the first local heating imposing a temperature between the glass transition temperature of the thermoplastic resin of the first assembly and the crystallization temperature of this resin, - the resumption, after the first relaxation, of the deposition of the fibrous layers and the deposition, on at least part of the first set that underwent the first relaxation, of a second set of stacked fibrous layers by automatic fiber placement, and - vacuum consolidation of the resulting stack of fibrous layers.
[0007] The glass transition temperature, denoted "Tg" hereafter, can be determined by differential scanning calorimetry (DSC). The crystallization temperature, denoted "Te" hereafter, corresponds to the temperature at which the material begins to stiffen. This crystallization temperature can be determined by differential scanning calorimetry during the cooling phase.
[0008] The invention makes it possible to reduce, or even eliminate, the stresses (stress relaxation) and deformations of the stacked layers as they are deposited, particularly for thick parts. The invention thus reduces or even eliminates the curvature of the part caused by internal stresses as the draping progresses, and prevents it from detaching from the substrate. This reduction in deformation simplifies, or even eliminates, the need for means of holding the part during draping, thereby simplifying its implementation.
[0009] The invention implements one or more dynamic relaxation phases in which the heated zone is displaced relative to the deposited fibrous layers. During each dynamic relaxation, a temperature between the Tg and Te of the thermoplastic resin of the last layer deposited is imposed, which is lower than the temperature required for consolidation, which produces melting or softening of the resin. Furthermore, the relaxation is sequential, with first relaxation of a first fraction of the stack, corresponding to the first layer, followed by relaxation of a second fraction of the stack, corresponding to the second layer. This second relaxation is performed during vacuum consolidation, or during a specific relaxation phase carried out prior to this consolidation.
[0010] Generally, the thermoplastic resin in the first set may be the same as, or different from, that in the second set. Within a given set, the thermoplastic resin may consist of a single thermoplastic polymer or a mixture of thermoplastic polymers. Various examples of usable polymers will be provided later.
[0011] Achieving sequential dynamic relaxation can make it possible to avoid integrating a heating element into the support or at least to greatly reduce its stress, thus overcoming the disadvantages mentioned above for continuous heating of the mold.
[0012] In one embodiment example, the second deposited assembly is subjected, before consolidation and while the deposition of the fibrous layers is interrupted, to a second relaxation, the second assembly being subjected, during the second relaxation, to a second heat treatment comprising a sweep of a surface of the second assembly, opposite to the support, by a second local heating, of limited extent to a fraction of this surface, in relative motion with respect to this surface, the second local heating imposing a temperature between the glass transition temperature of the thermoplastic resin of the second assembly and the crystallization temperature of this resin.
[0013] In this case, a specific relaxation is performed for the second set of layers which is completed before vacuum consolidation.
[0014] It should be noted that at least three sets of layers can be deposited before vacuum consolidation. In this case, dynamic relaxation, as described above, can be performed for each deposited set, or the dynamic relaxation of the last deposited set can be omitted, and vacuum consolidation can proceed directly. This consolidation step may employ known techniques that are not detailed here.Thus, in particular, after the second relaxation and before vacuum consolidation, it is possible to carry out (a) a deposition, on at least part of the second assembly which has undergone the second relaxation, of a third assembly of stacked fibrous layers by automatic placement of fibers, and (b) a third relaxation, while the deposition of the fibrous layers is interrupted, the third assembly being able to be subjected, during the third relaxation, to a third heat treatment comprising a sweep of a surface of the third assembly, opposite to the support, by a third local heating, of limited extent to a fraction of this surface, in relative motion with respect to this surface, the third local heating being able to impose a temperature between the glass transition temperature of the thermoplastic resin of the third assembly and the crystallization temperature of this resin.
[0015] In one example of implementation, prior to vacuum consolidation, a vacuum relaxation is performed on the last set of deposited layers.
[0016] This characteristic advantageously allows for the relaxation of internal stresses generated by the deposition of the last set of layers, thus preventing any risk of stack deformation. Placing the entire stack under vacuum during the relaxation of the last layer allows the stack to be pressed firmly onto the substrate. A relaxation sweep is performed across the surface of the last layer while the vacuum is maintained. The stresses are thus relaxed within the stack, resulting in a geometry imposed by the vacuum. The vacuum is maintained during cooling, preserving the geometry after the relaxation operation.
[0017] In a specific case, the relaxation of each of the deposited layers can be performed under vacuum. More generally, at least one of the deposited layers can be relaxed under vacuum (any set can be relaxed under vacuum).
[0018] In one embodiment example, the thermoplastic resin present on one face, located on the support side, of the first assembly which underwent the first relaxation is subjected, during the second relaxation, to a temperature at least equal to its glass transition temperature.
[0019] This characteristic helps avoid introducing new stresses into the stack thickness by minimizing the temperature gradient through the thickness during the second relaxation, thus further improving the quality of the resulting part. The thermoplastic resin of the first relaxed stack is therefore subjected, during the second relaxation, to a temperature at least equal to its Tg throughout the entire thickness of the first relaxed stack (the temperature increases along the thickness of the first relaxed stack as one moves towards the second stack). As will be described later, various solutions can be implemented to minimize this gradient.
[0020] In one example embodiment, the second local heating defines at least a first heating zone imposing a first temperature between the glass transition temperature and the crystallization temperature of the thermoplastic resin of the second assembly, and a second heating zone imposing a second temperature, lower than the glass transition temperature of the thermoplastic resin of the second assembly, the heated zone being swept successively by the first heating zone and then by the second heating zone.
[0021] This characteristic helps control the temperature gradient through the stack's thickness during the cooling of the heated zone by allowing for greater stress relaxation through the successive sweep provided by the second heating zone. In a specific case where the thermoplastic resins differ between the first and second sets, the initial temperature can also be between the Tg and Te of the thermoplastic resin in the first set, and the second temperature can also be lower than the Tg of the thermoplastic resin in the first set.
[0022] In one example of the design, the manufactured part has an open geometry.
[0023] In particular, the manufactured part can be a panel.
[0024] The invention is of particular interest for canceling internal stresses and deformations of an open panel-type part with a large thickness, such as a fuselage panel, a wing panel or a central box panel, among other possible examples.
[0025] In one embodiment, at least part of the deposited fibrous layers has at least locally a dome shape, the extent of the associated local heating covering an area between two meridians of the dome and corresponding to a fraction of the dome's surface, and the associated local heating being in rotation around an axis of the dome relative to the latter.
[0026] Such a feature corresponds to the application of the invention to a type of curved part, which can be open or closed. As will be further described below, it should be noted that the invention is not limited to a particular geometry for the manufactured part.
[0027] In particular, the manufactured part may be a tank, and at least part of the deposited fibrous layers may define a structure comprising a cylinder, intended to form at least part of a body of the tank, and at least two domes located at a respective end of the cylinder, the extent of the associated local heating covering an area between two meridians of this structure and corresponding to a fraction of the area of this structure, and the associated local heating being able to rotate about an axis of this structure.
[0028] In one embodiment, each set of fibrous layers is deposited on a support having an evolving shape along a first direction, and in which each local heating takes up the evolution of the shape of the support along the first direction and carries out the sweeping of the surface of the corresponding set along a second direction transverse to the first direction.
[0029] This case corresponds to the application of the invention to a situation where the local heating adapts to the shape of the room by following its evolving profile.
[0030] In one exemplary embodiment, each set of fibrous layers comprises carbon fibers, glass fibers, aramid fibers, or a mixture of such fibers.
[0031] In one embodiment, the thermoplastic resins of the fibrous layer assemblies are identical or different and each comprise: a polyaryletherketone polymer (PAEK), a polyetheretherketone polymer (PEEK), a polyetherketoneketone polymer (PEKK), a polyethersulfone polymer (PES), a poly(phenylene sulfide) polymer (PPS), a polyetherimide polymer (PEI), or a mixture of these polymers.
[0032] The aforementioned features and advantages, as well as others, will become apparent upon reading the detailed description that follows. This detailed description refers to the attached drawings. Brief description of the drawings
[0033] The attached drawings are schematic and primarily intended to illustrate the principles of the presentation. In these drawings, identical elements (or parts of elements) are identified by the same reference symbols from one figure to another. [Fig. 1] Figure 1 represents, schematically and partially, the deposition of a first set of fibrous layers by AFP in the context of an example of a process according to the invention. [Fig. 2] Figure 2 represents, schematically and partially, the first relaxation to relax the constraints of the first deposited set. [Fig. 3] Figure 3 schematically and partially represents a detail of a heating wall that can be used for local heating. [Fig. 4] Figure 4 schematically and partially represents the deposition of a second set of fibrous layers by AFP on the first relaxed set. [Fig. 5] Figure 5 represents, schematically and partially, the second relaxation to relax the constraints of the second deposited set. [Fig. 6] Figure 6 schematically and partially represents another example of a process according to the invention in which, during the second relaxation, a sweep is carried out with heating zones having different temperatures in order to control the cooling. [Fig. 7] Figure 7 schematically and partially represents the realization of a tank made of thermoplastic composite material in the context of an example according to the invention. [Fig. 8] Figure 8 schematically and partially represents the realization of a dome in thermoplastic composite material in the context of another example according to the invention. [Fig. 9] Figure 9 represents, schematically and partially, the realization of a panel in thermoplastic composite material in the context of another example according to the invention. [Fig. 10] Figure 10 schematically and partially illustrates the construction of a room with an evolving shape and localized heating that follows the room's profile. [Fig. 11] Figure 11 schematically illustrates the implementation of several localized heating systems. [Fig. 12] Figure 12 schematically represents the implementation of a local heating device whose size corresponds to the largest dimension of the assembly to be relaxed. Description of the implementation methods
[0034] Figure 1 schematically and partially illustrates the deposition by AFP, on a support 10, of a first set El of stacked fibrous layers 3-1 in the context of an example of a process according to the invention.
[0035] Figure 1 illustrates part of the structure of a dispensing head of a device for implementing an AFP technique. The structure of the illustrated dispensing head is known per se. The dispensing head is fed by a fibrous strip 3 composed of one or more fibrous strands impregnated with a thermoplastic resin, which is draped over the support 10 to deposit each of the layers 3-1. The strip 3 is conveyed by a conveying element (not shown) to a pressure application element 7 located on the side of the support 10, in the direction indicated by the arrow Fl.
[0036] The pressure application element 7 applies pressure to the impregnated strip 3 to deposit it onto the substrate 10. The pressure application element 7 may be in the form of a roller. The dispensing head also includes a heating element 9 capable of heating the strip 3 and the last deposited layer in the vicinity of, or directly on, the pressure application element 7. This heating element 9 heats the impregnated strip 3 during its deposition and also heats the last deposited layer to liquefy the thermoplastic resin and thus impart the desired adhesion to the deposited strip. In the illustrated case, the heating element 9 is a laser, but those skilled in the art will readily recognize that other heating methods can be used.
[0037] During application, the dispensing head is mobile in order to apply the impregnated strip 3 to the desired area of the substrate 10 (the movement of the head is indicated by arrow F2) and thus deposit each of the layers 3-1 of the assembly El. Elements ensuring good adhesion of the first layer deposited on the substrate 10 and forming a thermal barrier with the substrate 10 are part of the state of the art known to those skilled in the art and are not shown. Similarly, elements ensuring good demolding of the final part from the substrate 10, such as the application of release agents if necessary, are also part of the state of the art known to those skilled in the art and are not detailed here.
[0038] Once all the layers 3-1 of the first assembly El have been deposited, the deposition of the layers is interrupted to perform a first relaxation, as illustrated in Figure 2. Thus, no additional fibrous layers are deposited during the first relaxation. In the illustrated example, the support 10 is a molding tool, and a vacuum bag 20 has been attached, in a sealed manner, to cover the first assembly El. The bag 20 is positioned on the side of a surface SI of the first assembly El that is opposite the support 10. The bag 20 may be, without limitation, made of polyimide or elastomeric material, reinforced or not, and is a known element in itself. The illustrated example concerns a case where the relaxations are performed under vacuum, but it should be noted that this does not depart from the scope of the invention when this is not the case.
[0039] The first assembly El is placed between the support 10 and the tarpaulin 20. The first relaxation is then performed by drawing a vacuum in an internal volume between the support 10 and the tarpaulin 20. This vacuum forces the tarpaulin 20 onto the first assembly El, thus conforming it between the support 10 and the tarpaulin 20 by applying a conforming pressure PC. During the first relaxation, the first assembly El undergoes a first heat treatment involving a localized heating of its surface SI by a heating device 30, imposing a temperature between the Tg of the resin of the first assembly El and its Te, in order to relax the stresses in the deposited assembly. This heating is indicated by arrow F3.In the illustrated example, the vacuum draw is maintained during the first heat treatment, during the sweeping of the SI surface by the local heating, as well as during the cooling of the heated area after this local heating.
[0040] In general, a person skilled in the art will be able to calibrate the heating power and the movement speed of device 30 to achieve the relaxation, taking into account, in particular, the distance of device 30 from the SI surface of the last deposited El assembly, the target temperature (between Tg and Te at least for the thermoplastic resin of the last deposited El assembly), and the minimum target time at that temperature. The area heated by the local heating is brought, during each relaxation, for example, to a temperature between 145°C and 250°C. The duration for which the thermoplastic resin(s) are subjected to a temperature between their Tg and Te in a heated area can be greater than or equal to 1 second, for example, between 1 second and 1 hour.
[0041] In general, the local heating element is in relative motion with respect to the surface SI of the last deposited set El; that is, only the local heating element can be mobile, only the surface SI can be mobile, or both the local heating element and the surface can be mobile with relative motion between the two. The local heating element can be moved continuously with respect to the surface SI of the last deposited set El, or alternatively, a stepwise movement can be performed in which the local heating element is stationary to process one area and then moved to process another in a static manner (sequential processing). During the first relaxation, the first local heating element can sweep at least 50%, for example at least 80%, or even substantially all, of the surface SI of the first set El.The invention is not limited to a full sweep of the surface of the fibrous layers, in particular if it is sought to relax only certain areas identified (by modeling or feedback from experience) as being the most problematic.
[0042] As will be described later, the local heating device can have various shapes, adapted to the geometry of the part to be manufactured, and its trajectory to sweep the surface to be treated can vary to a large extent.
[0043] The heating device 30 may include at least one heating panel 32 positioned opposite the surface SI. The panel 32 is located outside the internal volume defined by the support 10 and the tarpaulin 20. The panel 32's area is limited to a fraction of the surface SI, or a fraction of the surface area of the support 10. Figure 3 schematically illustrates an example of a usable panel 32 comprising a plurality of infrared lamps 323 attached to a frame 321. Those skilled in the art will recognize that other methods can be used to produce the desired local heating. For example, the shape of the infrared lamps 323 can be varied by using curved lamps, or alternatively, pulsed flash lamps (lasers) or induction heating can be used.The wall 32 can be mounted on a robotic arm to perform the scanning; in particular, the wall 32 can be permanently mounted on the robotic arm used during draping, or simply positioned there for relaxation. Other variations are possible, such as guiding the heated wall on a gantry or rails to traverse the surface to be treated.
[0044] Once the first relaxation is complete and, in the example considered here, the tarpaulin 20 is removed, the deposition of the fibrous layers by AFP resumes. Figure 4 shows the deposition of a second set E2 of stacked 3-2 fibrous layers onto the first relaxed set E1R. The second set E2 can, as illustrated, cover the entire first relaxed set E1R, or only a portion of it. The deposition of the 3-2 layers is carried out similarly to that described above for the 3-1 layers using the AFP deposition head. The 3-2 layers of the second set are made of thermoplastic pre-impregnated fibrous material. The second set E2 can, as illustrated, be deposited in contact with the first relaxed set E1R.
[0045] Once all the layers 3-2 of the second assembly E2 have been deposited, the deposition of the layers is stopped to proceed with a second relaxation as illustrated in Figure 5. Thus, no additional fibrous layers are deposited during the second relaxation. In the illustrated example, the tarpaulin 20 is repositioned in a hermetic manner so as to cover the overlap of the first relaxed assembly E1R and the second assembly E2. A vacuum is drawn as described above to conform the stack formed by the assemblies E1R and E2, between the support 10 and the tarpaulin 20, by applying the PC pressure. In the case where the second assembly E2 does not cover the entire surface of the first relaxed assembly E1R, a vacuum environment can be created that does not completely cover the first assembly E1R.During the second relaxation, the second assembly E2 undergoes a second heat treatment. This involves sweeping its surface S2 with localized heating produced by device 30 to impose, in the illustrated example, a temperature between the Tg and its Te for each resin in the stack. More precisely, the face FAI of the first relaxed assembly E1R, located on the side of support 10 or on the opposite side from the second assembly E2, is subjected, during the second relaxation, to a temperature at least equal to the Tg of the thermoplastic resin present. The face FA2 of the first relaxed assembly E1R, located on the opposite side from support 10 or on the side of the second assembly E2, is subjected, during the second relaxation, to a temperature intermediate between the Tg and Te of the resin present. As illustrated in Figure 5, the temperature throughout the thickness of the first relaxed assembly E1R increases as one moves from face FAI to face FA2.In the example considered here, the temperature gradient is controlled throughout the thickness by imposing a temperature between the Tg and Te of the thermoplastic resin(s) present across the entire thickness of the stack formed by the deposited E1R and E2 assemblies. Several solutions can be implemented to achieve this control of the thermal gradient. One solution is to integrate a heating element into the support 10, activated at a moderate temperature, only during relaxations following the initial relaxation, in order to avoid the drawback of continuous mold heating mentioned above. Another solution, which can be used as an alternative or in combination with the first, is to control the sweep speed of the local heating element, specifically to slow it down in order to achieve deeper heat diffusion within the stack.In the illustrated example, the vacuum is maintained during the second heat treatment, during the sweeping of the S2 surface by the local heating, as well as during the cooling of the heated area after this local heating.
[0046] Figure 6 provides another example in which the second local heating defines two distinct heating zones to control the cooling gradient of the thermoplastic resin after heating it to a temperature above the Tg temperature. In this case, the heating device 30-1 defines a first heating zone ZI at a first temperature between Tg and Te of the thermoplastic resin in the second set, and a second heating zone Z2 at a second temperature, lower than the first temperature, for example lower than the Tg of the thermoplastic resin in the second set, for example between 50°C and 100°C.
[0047] A given area of surface S2 is first swept by the first zone Z1 and then by the second zone Z2 in order to control the cooling gradient and minimize the installed stresses. Initially, the cooling rate is less than or equal to 10°C per minute until a temperature between 50°C and 100°C is reached. Subsequently, after the passage of the second zone Z2, the temperature is homogenized to a temperature between 50°C and 100°C throughout the entire thickness of the stack, as illustrated in the temperature evolution graph. This minimizes the temperature gradient behind the heating device 30-1. This gradient management method may be preferred for heating devices that are small relative to the structure being reinforced.Of course, the scope of the invention remains unchanged if a heating device with more than two heating zones at distinct temperatures is used. As described above for the first relaxation, the second local heating zone can cover at least 50%, for example at least 80%, or even substantially all, of the surface area S2 of the second assembly E2 during the second relaxation.
[0048] In the example considered here, after relaxation is complete, the resulting stack undergoes vacuum consolidation in an autoclave or oven using a method known per se. Vacuum consolidation is performed after the deposition of the second assembly, E2, and its possible relaxation. Vacuum consolidation, possibly with the addition of extra pressure in the autoclave, results in bonding between all the layers of the first and second assemblies through compaction and interpenetration of the polymer chains on either side of their interface.
[0049] Generally, the number of 3-1, 3-2 layers deposited for each El, E2 assembly will be determined by a professional skilled in the art based on the accumulation of internal stresses within the layers during the deposition phase and the limit beyond which these layers will begin to deform and / or cause detachment from the substrate. The professional's determination of the number of layers deposited will also depend on the application and the heating and, if necessary, vacuum capabilities used to ensure proper relaxation. For example, each El, E2 assembly may comprise at least 10 3-1, 3-2 layers, for instance, between 10 and 30 3-1, 3-2 layers, or even between 10 and 20 3-1, 3-2 layers.An assembly can, of course, contain fewer than 10 layers, resulting in a longer deposition time before final consolidation and therefore an increased manufacturing cost for the part. Naturally, the number of layers 3-1, 3-2 deposited for each assembly E1, E2 can be the same or different, and each deposited assembly can include areas of reduced thickness, that is, areas with a smaller number of layers. In other words, each assembly can have a variable number of layers depending on the area considered.
[0050] The choice of reinforcing material and resin depends on the intended application. For example, the thermoplastic resins in the fiber layer assemblies may be identical or different and each may include: a polyaryletherketone (PAEK) polymer, a polyetheretherketone (PEEK) polymer, a polyetherketoneketone (PEKK) polymer, a polyethersulfone (PES) polymer, a poly(phenylene sulfide) (PPS) polymer, a polyetherimide (PEI) polymer, or a mixture of these polymers. In one particular case, the thermoplastic resin in the first assembly may be PEI and the thermoplastic resin in the second assembly may be PEAK or PEEK. In another particular case, the thermoplastic resin in the first assembly may be a mixture of PEI and PEAK, or PEEK, or PEKK.
[0051] The examples just described concern the manufacturing of a part by implementing two sequences of AFP deposition and subsequent relaxation. It naturally remains within the scope of the invention if the deposition is continued with at least a third AFP deposition / relaxation sequence, and the characteristics described for the first and second sequences also apply to subsequent sequences. Depending on the shape of the local heating system, the surface area of certain deposited assemblies, and the total number of assemblies, it is also possible that some assemblies may undergo, in whole or in part, several thermal relaxation cycles.
[0052] In the example just described, a simplified representation of the scanning path and the part geometry was used. The following section describes various possibilities for these aspects in more detail.
[0053] Figure 7 illustrates the fabrication of a tank by implementing an example of a process according to the invention, in which deposited layers define a cylinder 50 and two end domes 52 intended to form the tank bottoms. Figure 7 illustrates a sweep relaxation of the local heating device 30-2. The structure being fabricated extends along a longitudinal axis X, which may correspond to an axis of revolution of the structure. The local heating corresponds, for example, to a sector covering an area between two meridians of this structure and rotates around the X-axis. Alternatively, the deposited structure could be rotated around the X-axis with the local heating element either moving or stationary. Naturally, the heating device implemented may contain different heating zones according to the principle described above.Indeed, we can have a larger number of assemblies to be deposited in the areas of the end domes which can have a final thickness greater than the thickness of the main body of the tank, and therefore have differentiated heating zones for the relaxation of these additional assemblies.
[0054] Figure 8 illustrates the fabrication of a dome 60 by implementing an example of a process according to the invention. Similar to what has been described previously, the local heating device 30-3 corresponds to an angular sector of the dome, covering an area between two meridians of the dome, in relative rotational motion around its X axis.
[0055] Figure 9 represents the application of an example of a process according to the invention to the manufacture of a panel 70, by sweeping a local heating device 30-5 along a broken line trajectory, for example so as to cover the entire surface of the last layer set deposited (movement along the entire width and length of the last layer set deposited).
[0056] In general, it should be noted that the invention applies to the manufacture of parts with various geometries. The manufactured parts can be closed or open, for example, cylinders closed or not at their ends, ferrules, for example for integration into a space launcher, or panels, for example aircraft fuselage panels, wing panels, or center box panels. The parts can be flat or curved. They may or may not have a changing cross-section, that is, a change in their local curvature. The following description, in conjunction with Figures 10 to 12, provides further details on the heating process that can be implemented.
[0057] Figure 10 illustrates the case where the local heating device 30-4 adapts to the shape of the room by following an evolving profile. The support 10-1 exhibits an evolving shape along a first direction Dl, for example with alternating protruding and recessed portions as illustrated. The recently deposited set of layers El conforms to the shape of the support 10-1. The local heating device 30-4 conforms to the shape of the support 10-1 and the assembly El. In the illustrated example, the device 30-4 consists of several heated walls 30-41 ... 30-4n which are offset along the first direction Dl and which have different inclinations so as to adapt to the profile of the assembly El. Each wall 30-41 ... 30-4n is connected to a frame 31 by means of respective positioning and inclination adjustment means 33-1 ... 33-n, known per se.The device 30-4 scans the surface of the corresponding assembly along a second transverse direction D2, for example, perpendicular to the first direction D1. It should be noted that as the scan progresses, walls 30-41 ... 30-4n may become deactivated, or conversely, activated, for example, depending on changes in the dimension of the assembly El measured along the first direction. The position and / or inclination of the walls 30-41 ... 30-4n may also be modified during the scan to adapt to any changes in the shape of the support.
[0058] Figure 11 illustrates the simultaneous use of several 30-5 local heating devices, for example, to cover different areas (respective zones) of the surface of the last set of deposited layers. The movement of one of the 30-5 devices can be linked to the movement of the other 30-5 devices, or alternatively, be independent of the latter.
[0059] Figure 12 shows a local heating device 30-6 covering the entire length of the last layer set deposited. In this case, the device 30-6 moves along the width of this set, for example to cover its entire surface.
[0060] A person in the trade will recognize that other variations are possible, such as a device covering the entire width of the last set deposited, or transverse to the length and width of this set, or even a plurality of devices having a joint movement, with for example a staggered distribution.
[0061] In general, the shape of the heating device can correspond closely to the shape of the surface of the last set of layers deposited, being flat or curved.
[0062] Generally speaking, and even though it depends on the shape and dimensions of the room in question, the extent of local heating can cover a fraction of the surface of the last set deposited, ranging from 1% to 50%, in particular between 3% and 15% or between 5% and 10%.
[0063] Although the present invention has been described with reference to specific embodiments, modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various embodiments illustrated / mentioned may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.
[0064] The expression "between ... and ..." should be understood as including the boundaries.
Claims
Demands
1. A method for manufacturing a part made of thermoplastic composite material, the method comprising: - the deposition on a support of a first set (El) of stacked fibrous layers (3-1) by automatic fiber placement, the fibrous layers being made of thermoplastic prepreg fibrous material, - the interruption of the deposition of the fibrous layers and the carrying out, while this deposition is interrupted, of a first relaxation, the first assembly being subjected, during the first relaxation, to a first heat treatment comprising a sweep (F3) of a surface (SI) of the first assembly, opposite the support, by a first local heating, of limited extent to a fraction of this surface, in relative motion with respect to this surface, the first local heating imposing a temperature between the glass transition temperature of the thermoplastic resin of the first assembly and the crystallization temperature of this resin, - the resumption, after the first relaxation, of the deposition of the fibrous layers and the deposition, on at least part of the first set (E1R) which underwent the first relaxation, of a second set (E2) of stacked fibrous layers (3-2) by automatic fiber placement, and - vacuum consolidation of the resulting stack of fibrous layers.
2. A method according to claim 1, wherein the second assembly (E2) deposited is subjected, before consolidation and while the deposition of the fibrous layers is interrupted, to a second relaxation, the second assembly being subjected, during the second relaxation, to a second heat treatment comprising a sweep (F3) of a surface (S2) of the second assembly, opposite the support, by a second local heating, of limited extent to a fraction of this surface, in relative motion with respect to this surface, the second local heating imposing a temperature between the glass transition temperature of the thermoplastic resin of the second assembly and the crystallization temperature of this resin.
3. The method according to claim 2, wherein, after the second relaxation and before vacuum consolidation, (a) a deposit is made on at least a part of the second assembly which has undergone the second relaxation, of a third assembly of stacked fibrous layers by automatic placement of fibers, and (b) a third relaxation is carried out, while the deposition of the fibrous layers is interrupted, the third assembly being subjected, during the third relaxation, to a third heat treatment comprising a sweep (F3) of a surface of the third assembly, opposite to the support, by a third local heating, of limited extent to a fraction of this surface, in relative motion with respect to this surface, the third local heating imposing a temperature between the glass transition temperature of the thermoplastic resin of the third assembly and the crystallization temperature of this resin.
4. A method according to any one of claims 1 to 3, wherein, prior to vacuum consolidation, the last set of deposited layers is relaxed under vacuum.
5. A method according to any one of claims 1 to 4, wherein the thermoplastic resin present on one face (FAI), located on the side of the support (10), of the first assembly (E1R) which underwent the first relaxation is subjected, during the second relaxation, to a temperature at least equal to its glass transition temperature.
6. A method according to any one of claims 1 to 5, wherein the second local heating defines at least a first heating zone (Z1) imposing a first temperature between the glass transition temperature and the crystallization temperature of the thermoplastic resin of the second assembly, and a second heating zone (Z2) imposing a second temperature, lower than the glass transition temperature of the thermoplastic resin of the second assembly, the heated zone being swept successively by the first heating zone and then by the second heating zone.
7. A method according to any one of claims 1 to 6, wherein the manufactured part has an open geometry.
8. Method according to claim 7, wherein the manufactured part is a panel.
9. A method according to any one of claims 1 to 7, wherein at least a portion of the deposited fibrous layers has at least locally a dome shape (52; 60), the extent of the associated local heating (30-1; 30-2) covering an area between two meridians of the dome and corresponding to a fraction of the dome's surface, and the associated local heating being in rotation about an axis (X) of the dome relative to the latter.
10. A method according to claim 9, wherein the manufactured part is a tank, and wherein at least a portion of the deposited fibrous layers defines a structure comprising a cylinder (50), intended to form at least a portion of a body of the tank, and at least two domes (52) located at a respective end of the cylinder, the extent of the associated local heating (30-1) covering an area between two meridians of this structure and corresponding to a fraction of the area of this structure, and the associated local heating being in rotation about an axis (X) of this structure.
11. A method according to any one of claims 1 to 10, wherein each set (El; E2) of fibrous layers is deposited on a support (10-1) having an evolving shape along a first direction (Dl), and wherein each local heating (30-4) takes up the evolution of the shape of the support along the first direction and carries out the sweeping of the surface (SI; S2) of the corresponding set along a second direction (D2) transverse to the first direction.
12. A method according to any one of claims 1 to 11, wherein each set (E1; E2) of fibrous layers comprises carbon fibers, glass fibers, aramid fibers, or a mixture of such fibers.
13. A method according to any one of claims 1 to 12, wherein the thermoplastic resins of the fibrous layer assemblies are identical or different and each comprise: a polyaryletherketone polymer (PAEK), a polyetheretherketone polymer (PEEK), a polyetherketoneketone polymer (PEKK), a polyethersulfone polymer (PES), a poly(phenylene sulfide) polymer (PPS), a polyetherimide polymer (PEI), or a mixture of these polymers.