Welding method and system

Abstract

The invention relates to a method for welding a first profiled composite part (5) with a thermoplastic matrix and particles, in particular reinforcing, electrically conductive and / or ferromagnetic fibres, such as a stiffener, to a second composite part with a thermoplastic matrix and particles, in particular reinforcing, electrically conductive and / or ferromagnetic fibres, such as an aircraft panel, the method comprising the steps of: - preheating a joining zone in which the first part is to be joined to the second part using a preheating means (20), in particular a contactless means, which is moved along the first part (5) while facing same in order to raise the temperature of the joining zone; induction-welding the first (5) and second (6) parts in the preheated joining zone using an inductor (10) which is moved along the same side of the first part (5) as the preheating means (20).

Description

[0001] Description

[0002] Title: Welding process and installation

[0003] Technical field

[0004] The present invention relates to the dynamic induction welding of composite parts with a thermoplastic matrix and particles, in particular fibers, electrically conductive and / or ferromagnetic, in particular for producing stiffened panel type structures in the aeronautical field.

[0005] Prior art

[0006] Currently, the majority of dynamic induction welding processes for carbon fiber composites move a single inductor over the assembly. This inductor may be preceded and / or followed by a pressing means.

[0007] The fuselage panel typically has electrically conductive lightning protection (LSP) on its outer surface to protect the aircraft. This lightning protection is usually made of copper, which is a better conductor of electricity than carbon fiber.

[0008] The presence of such lightning protection makes it difficult to focus induction heating in the carbon fibers, because the energy supplied by induction tends to concentrate in the lightning protection, leading to a risk of overheating and degradation of the material at the level of the lightning protection and / or a risk of deconsolidation.

[0009] Application EP2801472A1 discloses a method in which a jet of a cooling fluid is directed into an area facing the inductor so as to limit the temperature rise.

[0010] W02008 / 133507A2 describes an induction welding process, in which the inductor is moved by a robotic arm.

[0011] Application FR3083733A1 discloses a welding method in which an induction-sensitive insert is introduced between the surfaces to be welded.

[0012] Application EP3772406A1 describes a method for welding an assembly of unidirectional fiber composites, in which the composite is preheated to a temperature below the melting temperature of the thermoplastic matrix, and then the part thus preheated is induction welded. Preheating may take place in a furnace, or by one or more prior passes of the inductor, or by means of a second inductor. The assembly may comprise a flat panel and a profiled part in the shape of a right angle. The inductor acts on the side of the panel opposite the profiled part.

[0013] None of these documents aims to address the issue of insert-free welding of a stiffener onto a fuselage panel with lightning protection.

[0014] The solution proposed in application EP3772406A1 is also incompatible with the presence of lightning protection, given that the inductor acts through the face of the panel opposite the stiffener, and that this face is precisely the one which carries the lightning protection on its surface in the case of a fuselage panel. Consequently, such lightning protection placed between the inductor and the assembly area would inevitably shield the induced currents, thus making it impossible, if not very difficult, to carry out the desired weld, despite the prior preheating of the assembly.

[0015] Furthermore, in the prior art, the heating is generally relatively heterogeneous depending on the design of the inductor, with a sudden rise in temperature followed by an equally rapid fall, due to the fact that the rest of the material has generally remained cold and tends to lower the overall average temperature by conduction. With a rapid fall in temperature, the polymer does not remain long enough in conditions conducive to welding (temperature above the melting temperature Tf). Furthermore, a solution which would aim to prepare the rise in temperature of the entire assembly via a heating mold would necessarily be a very energy-consuming solution and would also require contact conditions between the parts which are difficult to ensure.

[0016] Statement of the invention

[0017] Thus, there remains a need for a solution for welding composite parts, one of which, such as an aircraft fuselage panel, may possibly have an electrically conductive surface material such as a grid or a conductive sheet, the other part being a profiled part such as a stiffener, the welding being carried out without degrading the materials or generating a risk of deconsolidation.

[0018] There is also a need to reduce the power of the inductor and make its design less critical, without degrading the quality of the weld, in order to facilitate the development of induction welding installations for composite parts.

[0019] Summary of the invention

[0020] The invention meets all or part of these needs by proposing a method for welding a first composite part, in particular profiled, with a thermoplastic matrix and particles, in particular reinforcing fibers, conductive and / or ferromagnetic, such as a stiffener, to a second composite part with a thermoplastic matrix and particles, in particular reinforcing fibers, conductive and / or ferromagnetic, such as an aircraft fuselage part, capable of having an electrically conductive surface material, in particular a conductive sheet or grid for protection against lightning, comprising the steps consisting of:

[0021] Preheating an assembly zone of the first part and the second part using a preheating means, in particular a contactless preheating means, moved along the first part opposite it to raise the temperature of the assembly zone, the surface material being when present located on the second part on the side opposite the first, welding the first and second parts by induction in the assembly zone thus preheated using an inductor moved along the first part on the same side as the preheating means.

[0022] By "surface material" is meant a material that extends at least partly closer to the surface than to the core of the part; this material may extend in the form of a grid or a sheet. It may be a grid or a sheet of copper or other electrically conductive metal. This element is also referred to as "lightning protection".

[0023] Thanks to the invention, it is possible to obtain a satisfactory weld while avoiding degradation of the materials despite the possible presence of lightning protection, and while limiting the risk of deconsolidation.

[0024] Thanks to preheating, when the inductor arrives, the two parts are at a temperature close to melting. Induction only provides the missing energy to reach the melting temperature at the interface between the parts and to carry out the weld.

[0025] Preheating helps prevent excessive temperature spikes that can be caused by too rapid a temperature rise. It also slows down the temperature drop, as the assembly may be hotter overall than without preheating. The open time for soldering, during which soldering is possible, will be longer, so the polymer healing at the interface and thus the mechanical performance will be better.

[0026] The heat provided by the preheating means and by the inductor can compensate each other and the asymmetry of the heating efficiency of one can be compensated by the other to homogenize the thermal at the welding interface of the parts.

[0027] The power injected into the assembly by the inductor can be lower than in the case without preheating, and thus the induced current is reduced in the fibers as well as in the lightning protection, when it is present.

[0028] The need for post-heating to enhance healing may also be reduced, although it may still be present.

[0029] Preferably, preheating is performed before applying pressure to the assembly using a front pressing means, such as a pressure roller.

[0030] The invention can make it possible to avoid the use of an induction-sensitive insert, placed between the two parts, contrary to the teaching of application FR3083733A1.

[0031] Preheating means

[0032] The preheating means may be designed and sized to compensate for thermal imbalances generated by the inductor, so that the temperature is homogeneous at the interface of the first and second parts.

[0033] The contactless preheating means may advantageously comprise an IR radiation source.

[0034] This IR radiation source may comprise at least one screen placed between at least one IR radiation emitting lamp and the first part to at least partially delimit an IR radiation exit window. The emitting lamp may be an incandescent lamp or a flash tube. The radiation is preferably emitted continuously over time, but alternatively it is emitted in a pulsed manner, in particular if a flash lamp or a laser is used.

[0035] Two or more incandescent lamps can be used, for example, in the form of tubes arranged side by side. An advantage of using an IR radiation source is the ease with which the power can be modulated, compared to other heating methods such as hot air blowing. In addition, heating is carried out without the need for air supply, and therefore with a more limited risk of oxidation. The energy supplied is also less dependent on the distance between the preheating means and the area to be heated than in the case of an inductor, which is very sensitive to the thickness of the air gap.

[0036] The exit window can have an elongated shape in the direction of movement of the radiation source. This slit can be given a constant width or not, depending on the desired temperature rise profile.

[0037] In the case where the first part is profiled and has a flange which is welded to the second part and a web which connects to the flange by a radius, the window may be located closer to the radius by which the flange connects to the web of the first part than to its free edge.

[0038] The contactless preheating means may also include at least one hot air blowing element, replacing the IR radiation source or in addition.

[0039] The contactless preheating means may also include a second inductor, replacing the IR radiation source or as a supplement.

[0040] The preheating means may be configured to expose the first part to an energy flow having a non-homogeneous spatial distribution depending on the direction of movement of the preheating means relative to the first part, with a greater energy flow on the upstream side than on the downstream side. It is thus possible to play on the kinetics of heat diffusion in the assembly, by allowing the heat supplied more intensely by the upstream side more time to diffuse into the assembly until the arrival of the inductor.

[0041] The preheating means and the inductor may be moved simultaneously, in particular using the same robot. Alternatively, the preheating means and the inductor are moved simultaneously, but using separate drive means, such as respective robots for example. Where appropriate, in particular when the preheating means is a source of IR radiation, a thermal insulator or a cooling system using cold air or other fluid may be added between the casing of the preheating means and the core of the profiled part, to avoid excessive heating thereof in the event of excessive proximity to the casing.

[0042] Preheating

[0043] Preheating can bring the maximum temperature of the second part to a temperature greater than or equal to 0.5 Td, where Td denotes the deconsolidation temperature of the part, preferably greater than or equal to 0.7 Td, while ensuring that it remains below the melting temperature and the deconsolidation temperature.

[0044] The preheating temperature is chosen according to the nature of the polymer(s) of the composites used. For example, for certain PEKK-based composites, preheating brings the surface temperature of the first part, opposite the preheating means, to 250°C or more, for example to around 300°C.

[0045] The power of the preheating means for ensuring preheating of the assembly zone is, for example, greater than or equal to 0.2 kW.

[0046] Post-'

[0047] The method may include the step of post-heating the assembly area after passage of the inductor.

[0048] The same means as for preheating, as mentioned above, can be used as post-heating means, in particular an IR radiation source or at least one hot air blowing element.

[0049] The post-heating means can be driven in movement with the inductor, by the same robot for example, or alternatively independently by a separate robot.

[0050] Other di

[0051] When the preheating means includes an IR radiation source, the shape of the lamp(s) used, their power and / or the shape of the housing containing the lamp(s) can be varied to obtain the desired temperature rise ramp. The speed of advance of the preheating means and the inductor, as well as the frequency of the inductor, can also be varied.

[0052] The method may advantageously include measuring the surface temperature at at least one point of the first or second part, and controlling the power of the preheating means as a function of the temperature thus measured, so as to maintain it within a predefined temperature range.

[0053] The speed of advancement of the inductor along the parts to be assembled is for example between 1 and 30 mm / s, preferably between 1 and 10 mm / s. The preheating means preferably moves at the same speed as the inductor, being for example carried by the same support as the latter.

[0054] The method may include cooling the inductor and / or spraying a cooling fluid, in particular cold air, onto an outer face of the assembly, to contain the temperature. The installation may thus include one or more nozzles for blowing cold air, in particular pulsed air, close to the inductor.

[0055] By "profiled part" we mean a non-flat part, having at least one part called "sole" intended to be pressed against the other part to be welded there and a part called "core" which remains distant from this other part.

[0056] The first profiled piece can be elongated, straight or curved. It can have a cross-section in the shape of an L, Omega, C, Z or inverted T, among other possibilities. It can serve as a stiffener, to form a stiffened panel with the second. The thickness of the flange that is applied against the second piece to be welded to it ranges, for example, from 0.5 to 10 mm, preferably from 1 to 4 mm.

[0057] The sole and the web can be connected by a radius, and make an angle of 90° or other than 90° between them, for example an angle between 60° and 120°.

[0058] The second part may have a flat or non-flat shape, or even be tubular. Its thickness ranges, for example, from 0.5 to 10 mm, preferably from 1 to 6 mm. The second part may be a flat panel, with single or double curvature, particularly from an aircraft fuselage, including lightning protection.

[0059] The composites may include reinforcing fibers comprising carbon fibers. At least one of the composite parts may alternatively include conductive or ferromagnetic particles capable of heating under the effect of the field generated by the inductor, such as nickel particles.

[0060] The thermoplastic polymer of the first or second part may be selected from polyaryletherketones (PAEK), including polyetherketone (PEEK) and polyetherketoneketone (PEKK), polyphenylene sulfide (PPS) and / or polyetherimide (PEI), PA6, among other polymers.

[0061] Facility

[0062] The invention also relates to an induction welding installation, for welding a first composite part, in particular profiled, with a thermoplastic matrix against a second composite part with a thermoplastic matrix, in particular for implementing the method according to the invention as defined above, comprising:

[0063] A support configured to be moved in a direction of advance along the first part arranged in contact with the second in the position where it is to be welded thereto, an inductor carried by the support, to weld the first part against the second in an assembly zone, a mobile contactless preheating means for dynamically preheating the assembly zone upstream of the inductor, during the movement of the latter, in particular a preheating means carried by the same support or by a different support, at least one mobile pressing means for exerting pressure on the assembly in front and / or behind the inductor.

[0064] The installation may include a post-heating means, in particular carried by the support, to post-heat the assembly zone downstream of the inductor.

[0065] The installation may include a pressing means between the preheating means and the inductor and / or a pressing means between the inductor and the postheating means. The installation may include a robot, for example a 6-axis robot, to move the support along the first part to be assembled to the second.

[0066] The preheating means may be selected from an IR radiation source, a second inductor and a hot air source, preferably an IR radiation source or a second inductor.

[0067] The installation may include any other characteristics already described above in relation to the process.

[0068] Brief description of the drawings

[0069] The invention may be better understood by reading the detailed description which follows, non-limiting examples of its implementation, and by examining the attached drawing, in which:

[0070] [Fig 1] Figure 1 shows in a partial and schematic manner an example of a welding installation for implementing the method according to the invention,

[0071] [Fig 2] Figure 2 represents a detail of Figure 1,

[0072] [Fig 3] Figure 3 is a schematic and partial cross-section of an example of a preheating and assembly means,

[0073] [Fig 4] Figure 4 is a view similar to Figure 2 of an alternative embodiment of the preheating means,

[0074] [Fig 5] Figure 5 is a view similar to Figure 2 of an alternative embodiment of the installation, with post-heating,

[0075] [Fig 6] Figure 6 is a view similar to Figure 2 of an alternative embodiment of the installation, with preheating by blowing hot air,

[0076] [Fig 7] Figure 7 is a view similar to Figure 2 of an alternative embodiment with two inductors,

[0077] [Fig 8] Figure 8 illustrates another two-inductor variant,

[0078] [Fig 9] Figure 9 is a cross-section of an example assembly with an Omega stiffener,

[0079] [Fig 10] Figure 10 is a view similar to Figure 9 with a C-shaped stiffener, [Fig 11] Figure 11 is a view similar to Figure 9 with a Z-shaped stiffener, [Fig 12] Figure 12 is a view similar to Figure 9 with an inverted T-shaped stiffener, [Fig 13] Figure 13 represents an example of an installation with two robots for moving the inductor and the preheating means respectively,

[0080] [Fig 14] Figure 14 is an example of a schematic temperature rise profile with an installation according to the prior art, without preheating means to carry out preheating,

[0081] [Fig 15] Figure 15 is a view similar to Figure 14 with a preheating means according to the invention upstream of the inductor to preheat the assembly zone, and

[0082] [Fig 16] Figure 16 represents temperature rise curves at the level of the face provided with lightning protection, in the case of an example according to the prior art without preheating and in the case of an example according to the invention with preheating.

[0083] Detailed description

[0084] Figure 1 illustrates a welding installation 1 comprising a robot 2 carrying a welding head 3 (also called a welding effector), and a support structure 4 on which the parts to be assembled are placed. This support structure 4 may not include any active cooling means.

[0085] The parts to be assembled may comprise a first profiled part 5 (also called a stiffener) and a second part such as an aircraft fuselage panel, as seen in Figure 3.

[0086] The first part 5 comprises a thermoplastic matrix and electrically conductive reinforcing fibers, such as carbon fibers, and has, for example, as illustrated, a corner shape with an L-shaped cross section, with a flange 5a which is fixed to the part 6 and a core 5b which is substantially perpendicular to it.

[0087] The second part 6 also comprises a thermoplastic matrix and electrically conductive reinforcing fibers, such as carbon fibers, as well as in this example a metallic lightning protection 7, located on the side of the second part opposite the first.

[0088] The invention is not limited to particular shapes of the parts to be assembled, and other shapes are possible, as will be detailed later.

[0089] The welding head 3 comprises, as can be seen more particularly in FIG. 2, a support 9 carrying an inductor 10 connected to an adaptation box 19, itself connected by cables and conduits 14 to a supply of electrical energy and cooling fluid.

[0090] The inductor 10 is for example supplied by an electric current at a frequency chosen in the range 50 kHz-10000 kHz.

[0091] The installation 1 comprises front 11 and rear 12 pressing means upstream and downstream of the inductor 10, to exert pressure on the assembly.

[0092] These pressing means 11 and 12 can be produced in various ways without departing from the scope of the present invention. They can in particular comprise rollers, rollers, pads, caterpillars or any other member suitable for exerting pressure.

[0093] In the example considered, these pressing means 11 and 12 are mounted on the welding head 3 and are thus movable with it. Alternatively, one and / or the other are supported otherwise, for example by one or more other robots.

[0094] The pressing means 11 and 12 may be mounted on cylinders 18, as illustrated, which may be pneumatic, hydraulic or electric, and make it possible to adjust the pressure applied to the assembly.

[0095] The installation may comprise one or more nozzles 60 for blowing pulsed cold air onto the outer surface of the assembly, close to the inductor 10, to contain the surface temperature to values ​​below a given threshold, and avoid degrading the polymer.

[0096] In accordance with the invention, the installation 1 comprises a preheating means 20 which makes it possible to locally raise the temperature of the parts 5 and 6 before the passage of the inductor 10.

[0097] This means of preheating can be achieved in various ways.

[0098] In the example of figures 2 and 3, the preheating means 20 comprises at least one infrared lamp 22 arranged in a casing 25.

[0099] An opening 24 is formed in the casing 25 for the exit of infrared radiation (IR) towards the sole 5a of the first part 5.

[0100] The housing 25 may be fixedly supported, as illustrated, by a support structure 21 connected to the support 9 and comprising one or more arms.

[0101] The opening 24 may be in the general form of a slot oriented longitudinally in the direction of movement of the welding head 3, of width w. The opening 24 may be delimited on at least one side by at least one screen 23, which may be formed by a wall of the casing 25 or by an added element. The width of the slot may be different at the front (or upstream) end than at the rear (or downstream) end, i.e. closest to the inductor 10. Thus, the power supplied by the radiation source may vary along the advance of the preheating means, leaving more time for the heat supplied to diffuse to the interface between the parts. For example, at the rear, the width is smaller and the heat supplied is less, limiting the risk of exposing the surface to excessive temperature.

[0102] In the example illustrated, the opening 24 extends over less than the total width of the sole 5a, being closer to the radius 5f connecting it to the core 5b than to the free edge of the sole 5a. In this way, the risk of overheating of the first part on its free edge with the induction is limited and thus a better homogeneity of the preheating temperature at the interface between the parts is obtained. The opening 24 makes it possible to compensate for the asymmetry generated by the induction, which preferentially heats the free edge.

[0103] The operation of installation 1 is as follows.

[0104] Parts 5 and 6 are pre-positioned in the configuration where assembly is to take place. A non-visible holding tool may be present, for example, at the rear of part 5 to hold it in position during the welding operation.

[0105] The welding head 3 is then brought by the robot arm 2 to a longitudinal end of the stiffener 5, so that the preheating means 20 can heat this end.

[0106] Then, the welding head 3 is moved continuously along the stiffener 5 (to the right in figures 1 and 2), at a speed chosen to allow compliance with the desired thermal profile.

[0107] The preheating means 20 makes it possible to locally preheat, dynamically, the future assembly zone to a temperature below the melting temperature of the thermoplastic material; during the movement of the head 3, the front pressing means 11 arrives at this zone and exerts pressure keeping the part 5 pressed against the part 6. Then, the inductor 10 passes over the zone, and the energy supplied by the inductor 10 brings the conductive fibers of the composites to a temperature higher than the melting temperature of the thermoplastic matrix, at the interface between the parts 5 and 6, making it possible to produce the desired weld. Finally, the rear pressing means 12 maintains pressure on the assembly during cooling.Figure 14 shows in a very simplified and purely illustrative manner an example of a temperature rise profile at the welding interface in the absence of preheating, as encountered in the prior art, and Figure 15 shows the same profile obtained with preheating according to the invention.

[0108] Due to the preheating, the energy to be supplied by the inductor is reduced and the temperature induced at the lightning protection 7 by the inductor does not cause degradation of the material. It can be seen that the temperature rise induced by the inductor can be lower in the invention than in the absence of preheating.

[0109] Figure 16 shows a comparative example of temperature curves observed at the level of the face carrying the lightning protection in the case of the prior art without preheating (solid curve) and in the case with preheating (dotted curve).

[0110] Thanks to preheating, the power of the generator that supplies the inductor can be reduced compared to the case without preheating (generator power reduced from P=55% of the maximum power in the absence of preheating to P=40% in the presence of preheating); moreover, the temperature observed at the level of the face carrying the lightning protection does not exceed 130°C in the presence of preheating, whereas in the opposite case it reaches more than 230°C.

[0111] Various modifications may be made to the installation without departing from the scope of the invention.

[0112] The installation may comprise a preheating means 20 movable relative to the inductor 10, so as to be able to follow curved trajectories and best match the relief of the parts to be assembled during the welding sequence, as illustrated in figure 4.

[0113] In this figure, the possibility has been illustrated for the parts to be assembled to have an elbow or a curvature 8, and to mount the preheating means 20 with at least one articulation 28 on the support 9 of the welding head 3 so as to be able to modify the orientation of the casing 25 and thus best follow the evolution of the shape of the parts during the movement of the head 3.

[0114] The welding head 3 shown in Figure 5 comprises a post-heating means 30 which makes it possible to slow down the cooling of the assembly after the passage of the inductor 10. This post-heating means is for example infrared and similar to the pre-heating means 20, and may comprise a casing 35 fixed to the support 9 of the head 3 by a support structure 31.

[0115] Preheating of the area to be welded can be done using other methods than infrared radiation.

[0116] For example, the area to be welded can be preheated with hot air blown onto the area, as illustrated in Figure 6. In the latter, it can be seen that the welding head 3 can comprise one or more hot air blowing elements 41, for example in the form of one or more cones, connected to a hot air source by one or more conduits 42, in order to blow hot air onto the part 5 upstream of the inductor 10 and preheat the assembly area.

[0117] A second inductor 43 can also be used as preheating means 20, as illustrated in FIG. 7.

[0118] This second inductor 43 can be connected to the same adaptation box 19 as the inductor 10, being for example electrically connected in series with the latter, or alternatively be connected to a separate box 44, having its own supply of electrical energy and cooling fluid, as illustrated in FIG. 8.

[0119] The first part 5 which serves as a stiffener or provides another particular function to the assembly can have various shapes, as can the second.

[0120] The first part 5 is for example a stiffener having an omega profile, as illustrated in figure 9, with two flanges 6a welded against the second part 5 and a web 5c which is spaced therefrom.

[0121] The first part 5 may also be in the form of a stiffener having a C-shaped profile, with a flange 5a fixed against the second part 6 and a web 5d which is spaced therefrom, as illustrated in Figure 10, or having a Z-shaped or inverted T-shaped profile as illustrated in Figures 11 and 12 respectively.

[0122] In Figure 13, the possibility is illustrated for the installation 1 to include more than one robot to independently support the inductor 10 on the one hand, and the preheating means 20 on the other hand.

[0123] In this example, the preheating means 20 is carried by a robot 80 which can be operated independently of the robot 2, thus making it possible to move the welding head 3 independently of the preheating means 20. Of course, various modifications can be made to the installation and the method without departing from the scope of the present invention.

[0124] For example, the assembled parts may be other than aircraft parts, for example wind turbine parts (blade or nacelle) or civil engineering parts (for example building dome).

[0125] The preheating and postheating means, as well as the pressing means, can be implemented in other ways.

Claims

Demands 1. A welding process for a first profiled composite part (5) with a thermoplastic matrix and particles, in particular reinforcing fibers, electrically conductive and / or ferromagnetic, such as a stiffener, onto a second composite part with a thermoplastic matrix and particles, in particular reinforcing fibers, electrically conductive and / or ferromagnetic, such as an aircraft panel, comprising the steps of: Preheat an assembly area of ​​the first part and the second part using a preheating means (20), in particular non-contact, moved along the first part (5) opposite it to raise the temperature of the assembly area, weld the first (5) and second (6) parts by induction in the assembly area thus preheated using an inductor (10) moved along the first part (5) on the same side as the preheating means (20).

2. Method according to claim 1, the second part (6) comprising an electrically conductive surface material, in particular an electrically conductive grid or mat (7), serving as lightning protection, on the side opposite to the first part (5).

3. Method according to any one of claims 1 and 2, the preheating means (20) comprising an IR radiation source.

4. Method according to claim 3, the IR radiation source being able to locally include screens (23), placed between at least one IR radiation emitting lamp (22) and the first part (5), to delimit at least partially one or more IR radiation exit windows (24).

5. Method according to claim 4, the exit window (24) having an elongated shape in the direction of movement of the radiation source.

6. Method according to any one of claims 4 and 5, the first part (5) comprising a base (5a) to be fixed to the second part, connected by a radius (5f) to a web (5b; 5c; 5d), the window (24) being located closer to the radius by which the base connects to the web of the first part than to its free edge.

7. Method according to any one of claims 1 and 2, the preheating means (20) comprising at least one hot air blowing element (41).

8. Method according to any one of claims 1 and 2, the preheating means (20) comprising a second inductor (43).

9. Method according to any one of the preceding claims, the preheating means (20) and the inductor (10) being moved simultaneously, in particular using the same robot (2).

10. A method according to any one of the preceding claims, comprising the step of post-heating the assembly area after the passage of the inductor (10).

11. Method according to any one of the preceding claims, the first piece (5) having a cross-section in the shape of an L, Omega, C, Z or inverted T.

12. Method according to any one of the preceding claims, the second part (6) being an aircraft fuselage part incorporating lightning protection (7).

13. Method according to any one of the preceding claims, the preheating raising the maximum temperature of the second piece (6) to a temperature greater than or equal to 0.5 Td, where Td denotes the deconsolidation temperature of this piece, preferably greater than or equal to 0.7 Td.

14. A method according to any one of the preceding claims, comprising measuring the surface temperature at at least one point of the first part (5) or the second (6), and controlling the power of the preheating means (20) as a function of the temperature thus measured, so as to maintain it within a predefined temperature range.

15. Method according to any one of the preceding claims, the preheating means (20) being configured to expose the first part (5) to an energy flux having a non-homogeneous spatial distribution according to the direction of movement of the preheating means relative to the first part, with a greater energy flux on the upstream side than on the downstream side.

16. A process according to any one of the preceding claims, the composites comprising reinforcing fibers comprising carbon fibers.

17. A method according to any one of the preceding claims, the preheating means (20) being designed and dimensioned to compensate for imbalances thermal generated by the inductor (10), so that the temperature is homogeneous at the interface of the first (5) and second (6) parts at the time and after the passage of the inductor (10).

18. Method according to any one of the preceding claims, the preheating means (20) being connected in an articulated manner (28) to a support (9) carrying the inductor (10), so as to be able to be moved along a curved piece.

19. Method according to any one of claims 1 to 17, the inductor (10) and the preheating means (20) being moved by respective robots (2; 80).

20. Induction welding installation (1) for welding a first composite part, in particular a profiled part, with a thermoplastic matrix, to a second composite part with a thermoplastic matrix, in particular for implementing the process according to any one of the preceding claims, comprising: A support (9) configured to be moved in a forward direction along the first part disposed in contact with the second in the position where it is to be welded to it, an inductor (10) carried by the support, for welding the first part (5) against the second (6) in an assembly area, a mobile non-contact preheating means (20) for dynamically preheating the assembly area upstream of the inductor (10), during the movement of the latter, at least one mobile pressure means (11, 12) for exerting pressure on the assembly in front of and / or behind the inductor during the movement of the latter.

21. Installation according to claim 20, comprising a mobile post-heating means (30) for dynamically post-heating the assembly area downstream of the inductor (10).

22. Installation according to any one of claims 20 and 21, comprising a press means (11) between the preheating means (20) and the inductor (10).

23. Installation according to claims 21 and 22, comprising a presser means (12) between the inductor (10) and the post-heating means (30). An installation according to any one of claims 20 to 23, comprising a robot (2) for moving the support (9) along the first part (5). An installation according to any one of claims 20 to 24, the preheating means (20) being selected from an IR radiation source, a second inductor (43) and a hot air blowing element (41), preferably an IR radiation source or a second inductor.

Images