EP4347213A1

EP4347213A1 - Heating apparatus for performing localised thermal activation of a composite part

Info

Publication number: EP4347213A1
Application number: EP22729604.3A
Authority: EP
Inventors: Benjamin MASSETEAU; Franck Bellon; Thomas PERRET; Guillaume VINCENT
Original assignee: Institut de Recherche Technologique Jules Verne
Current assignee: Institut de Recherche Technologique Jules Verne
Priority date: 2021-05-25
Filing date: 2022-05-18
Publication date: 2024-04-10
Also published as: FR3123245A1; FR3123245B1; WO2022248315A1

Abstract

The invention relates to a heating apparatus (1) for performing localised thermal activation of a predetermined zone (Z) of a thermoplastic polymer matrix composite part (P), comprising: - a heating device (2) with infrared emitter(s) (6), - a mask (3) comprising at least one perforated zone (4), the mask (3) being arranged relative to the composite part (P) without contacting said part and so as to at least partially superimpose said at least one perforated zone (4) with said predetermined zone (Z), the mask (3) being positioned between the composite part (P) and the heating device (2), - an element (5) for controlling the heating device (2), the apparatus (1) being configured to allow localised thermal activation of said predetermined zone (Z) through said mask (3) at a temperature at least equal to the melting temperature of the thermoplastic polymer and also to preserve the other zones (Za) of the composite part (P) from its deconsolidation temperature.

Description

Title: Heating device for performing localized thermal activation of a composite part Technical area

The present invention relates to a heating apparatus for carrying out localized thermal activation, also called localized heating, of a predetermined zone of a composite part with a thermoplastic polymer matrix as well as a heating method for the localized thermal activation of a predetermined zone of a composite part with a thermoplastic polymer matrix. The invention also relates to an installation for supplying material, in particular by overmolding or welding, allowing the localized supply of at least one thermoplastic polymer, to a predetermined zone of a composite part, comprising such a heating device as well as a process for supplying material. Prior technique

To achieve localized thermal activation of a part made of composite material with a thermoplastic polymer matrix with a view to attaching and welding another thermoplastic polymer to it, by overmolding or welding or another process for adding material, the use of processes involving conduction or induction, the use of a plasma torch or even a laser.

However, the use of these types of heating has a number of disadvantages. Indeed, either the heating is too diffuse or, in the case of conduction, the heating induces, due to the contact between the heating element and the part, surface defects. As far as the laser is concerned, the travel time of the laser beam between the two ends of the zone to be heated of the part can induce significant temperature differences between these ends which are the cause of disparities in terms of mechanical resistance to level of the interface between the part and the added thermoplastic polymer.

We also know the use of infrared emitters whose shapes are adapted for localized thermal activation of the part. However, there is a limited choice on the market in the shapes of such emitters, in particular for the minimum surface to be heated, and their cost is very high because of their specific shapes.

Known from CA2457743 is an infrared emitter comprising a first parabolic reflector and a lower reflector having a lower opening through which all the radiation is directed. DE 202013 001996 and FR 2777 496 describe infrared heating systems.

There is thus a need to benefit from a heating apparatus, a heating method making it possible to heat efficiently and at lower cost a localized zone of a composite part with a thermoplastic polymer matrix, as well as an installation and a process for supplying material making it possible to add a thermoplastic polymer to this zone, by overmolding or welding or another process for supplying material.

Disclosure of Invention

The invention meets all or part of this need. It achieves this thanks to, according to one of its aspects, a heating apparatus for carrying out localized thermal activation of a predetermined zone of a composite part with a thermoplastic polymer matrix, comprising: a heating device with emitter(s) infrared, a mask comprising at least one perforated zone, the mask being arranged relative to the composite part, in particular parallel thereto, without contact with the latter and so as to at least partially superimpose said at least one perforated zone with said predetermined zone, the mask being interposed between the composite part and the heating device, a control member of the heating device, the apparatus being configured in order on the one hand to allow localized thermal activation of said predetermined zone through said mask at a temperature at least equal to the melting temperature of the thermoplastic polymer, and on the other hand to preserve the other zones of the composite part from the tem deconsolidation period of the composite part.

The mask is preferably made of metal, in particular of aluminum or of steel, in particular of stainless steel. The mask is designed to withstand a high temperature, in particular above 600°C. It advantageously comprises a metal sheet. The mask preferably has a flat shape. The mask may alternatively have a three-dimensional shape. The thickness of the mask can be between 1 and 10 mm, being for example 5 mm, in a non-limiting manner, a wide range of thicknesses being possible.

Said at least one perforated zone of the mask advantageously has a shape or geometry similar to that of said predetermined zone of the composite part. The perforated zone can form a slot or any other shape which depends at least in part on the surface to be heated, that is to say on said predetermined zone of the composite part.

The or each perforated zone preferably has, at least on the side of the mask which faces the composite part, a surface less than or equal to that of the corresponding predetermined zone. The surface of the perforated zone can be between 20% and 90%, preferably between 50% and 80%, of the surface of the predetermined zone. This surface is chosen in particular as a function of the shape of the perforated zone, and therefore of the predetermined zone, of the distance between the mask and the composite part to be heated locally and of the surface power generated by the heating device.

Said at least one perforated zone can be produced by any cutting means making it possible to obtain a clean cut in order to avoid or limit edge effects, in particular diffraction, such as for example machining or water jet cutting. .

In a particular embodiment, said at least one perforated zone may include at least one chamfer made inside it, aimed at ensuring that the surface of the perforated zone on the side of the mask which faces the composite part is less than that of the opposite side of the mask facing the heating device. This can make it possible to reduce the width of the beam of infrared radiation coming to heat the composite part in the interval between the mask and the composite part and therefore to limit the surface of the deconsolidated zone of the composite part.

The relative positioning of the mask and of the heating device and/or the positioning of this assembly of the mask and of the heating device relative to the composite part are preferably provided so as to allow heating to the desired temperature of said predetermined zone through of said at least one perforated zone.

In particular, the distance between the composite part and the mask can be between 5 and 40 mm, preferably between 5 and 20 mm, for example equal to 20 mm. This distance depends in particular on the surface of the predetermined zone which is heated to the desired temperature. This distance also depends on the desired heat diffusivity in and around the predetermined area, therefore also of the type of fiber and thermoplastic polymer.

The distance between the mask and the heating device with infrared emitter(s), or infrared lamp(s), can be between 5 and 50 mm, preferably between 15 and 30 mm, for example equal to 30 mm. This distance may depend in particular on the type of infrared emitter, its geometry and the surface of the perforated area.

The heating device with infrared emitter(s) can be arranged in a plane parallel to the mask.

The mask can reflect at most 10%, better still at most 5%, of infrared, in particular of wavelength between 700 nm and 1 mm.

The device may include a movable frame relative to the composite part. The assembly of the mask and the heating device is preferably carried by the frame of the apparatus. The distance between the mask and the heating device can be adjustable although they are both integral with each other, being fixed to the frame. Alternatively, the distance between the mask and the heating device within the frame is not adjustable, being for example fixed at 30 mm.

The composite part may have a substantially planar shape. In this case, the mask, also plane in this case, can be arranged substantially parallel to the composite part.

The composite part may as a variant have a non-planar shape. In the latter case, the mask may also be non-planar, the three-dimensional shape being obtained by a surface offset, in order to be able to be positioned parallel at any point to the surface of the composite part to be heated. Also in this case, the infrared emitter placed behind the mask can be positioned tangent to the surface of the composite part to be thermally activated.

The composite part can be made of a composite laminate. Such a laminate is for example obtained by superimposing plies of fibers, pre-impregnated with the thermoplastic polymer matrix, the plies of fibers possibly having different fiber orientations, for example oriented at 0°, +45°, -45° and 90°.

The composite part can be carried by a support and/or placed in a mold. No element is preferably placed between the mask and the composite part during heating using the device. The thermoplastic polymer of the composite part is for example chosen from the group consisting of polyamides (PA), polyaryletherketones (PAEK), polycarbonates (PC), polyetherimides (PEI), polypropylenes (PP), polyethylenes (PE ), polyphenylene sulphides (PPS), acrylonitrile butadiene styrene (ABS), polyformaldehydes (POM), styrene-acrylonitriles (SAN), polyphenylene sulphides (PPS), polypropylenes (PP), polyethylenes (PE ) and polyethylene terephthalates (PET).

The composite part generally includes reinforcing fibers. The fibers of the composite part are for example chosen from the group consisting of fibers of glass, aramid, in particular Kevlar®, carbon, basalt, natural fibers, in particular flax, preferably carbon fibers and of glass.

The composite part can be of large dimensions, being for example intended for the aeronautical, space, wind power, automotive sector or for another industrial sector, in particular sports and leisure.

The apparatus may include at least one temperature sensor, in particular a pyrometer, configured to measure the surface temperature of the composite part, at least in said predetermined zone.

The control member is preferably configured to control the heating device according to a heating cycle comprising at least one temperature rise ramp and possibly a plateau, the heating cycle preferably lasting less than or equal to 3 min, in particular less than or equal to 2 min, more preferably less than or equal to 1 min and 30 s, or even less than or equal to 1 min.

In this case, and in the case where the device comprises a temperature sensor, said at least one temperature sensor can be configured to supply at least one piece of information to the control member relating to the temperature at least in said predetermined zone , the control member being configured to program and/or adapt the heating cycle as a function of said at least one item of information, said at least one item of information possibly being in particular a PID type regulation. In particular, this can make it possible to prevent the temperature of said predetermined zone from exceeding the setpoint temperature given by the chosen ramp or even from exceeding the degradation temperature of the composite part, in particular of the thermoplastic polymer of the part. composite. “Composite part deconsolidation temperature” means the temperature at which the composite part loses its material health, at which it degrades reversibly. The composite part can be heated and compressed again to regain its initial material health. Indeed, "deconsolidation" consists of the appearance of porosity, the increase in the thickness of the composite part and the reduction in its mechanical properties, which is possible if the thermoplastic polymer has come too close to its temperature of merger. The deconsolidation temperature of the composite part is synonymous with the deconsolidation temperature of the thermoplastic polymer matrix composite of the composite part. In the case where the thermoplastic polymer of the matrix of the composite part is PEKK, the latter has a melting point Tm of 337°C. Deconsolidation of the composite takes place around 310°C, slightly below Tf. This deconsolidation temperature does not only depend on the melting temperature of the thermoplastic polymer, but also on the type of fibers, the type of textile used, the process implemented to produce the composite part.

By "degradation temperature" is meant the temperature from which the thermoplastic polymer matrix contained in the composite part begins to degrade irreversibly, with a loss of mechanical properties and other physico-chemical properties. Indeed, “degradation” concerns a set of chemical modifications (oxidation and cross-linking of certain chains of the thermoplastic polymer). The degradation appears at high temperature (often well above the melting temperature T _f ). This is irreversible damage to the polymer.

The apparatus is preferably configured so that the temperature reached by said predetermined zone is at least higher than the melting point T _f of the thermoplastic polymer constituting the matrix of the composite part, and lower than the degradation temperature of the matrix contained in the composite part.

Thanks to the invention, the heating is localized and therefore the deconsolidation temperature of the composite part is not reached in areas other than said predetermined area.

In a particular example where the thermoplastic polymer of the matrix of the composite part is a PAEK, the deconsolidation temperature of the composite part is approximately 310°C, that is to say approximately 30°C below the melting temperature T _f of the matrix. For this, the control member is preferably configured, in particular programmed, so as to control the heating device so as not to exceed this or these conditions.

In a particular embodiment, the infrared emitter or emitters of the heating device comprise double filaments, in particular arranged between them to have a cross-section in the shape of an “8”. As a variant, the infrared emitter or emitters are monofilaments.

The wavelength, the type of emitter(s) and/or the surface heating power are preferably chosen according to the nature of the thermoplastic matrix composite making up the composite part (in particular the type of fibers), the its thickness, the heating rate required, the distance between the mask and the infrared emitters and the distance between the mask and the composite part.

The number of infrared emitters can vary according to the surface of the composite part to be heated, that is to say the surface of said predetermined zone, according to the planar or non-planar shape of the composite part, the nature of the part composite, the heating rate required, or the type of emitters used. The number of transmitters can be between one and five per perforated area, preferably between one and three per perforated area. The surface heating power can be between 50 and 500 kW/m ² . This surface heating power is preferably chosen so as to allow heating of said predetermined zone which is as rapid as possible. This surface power can be chosen according to the nature of the composite part to be heated and/or its thickness. It can be chosen so as to obtain a heating rate, in particular in the temperature rise ramp of the heating cycle, of between 2° C./s and 10° C./s.

Another subject of the invention, according to another of its aspects, in combination with the foregoing, is a material supply installation allowing the localized supply of at least one thermoplastic polymer, to a predetermined zone of a part. composite, the installation comprising a heating device as defined above and a device for supplying material, in particular by overmolding or welding, to allow the supply of said at least one thermoplastic polymer, preferably chosen to be compatible with the thermoplastic polymer of the composite part, in said predetermined zone after heating the latter using the heating device. According to one embodiment, the installation comprises a mold arranged to support the composite part during or after the localized thermal activation, said mold being a stamping mold for the 3D shaping of the composite part or a mold for injection having a cavity for the composite part.

In this case, the material supply device comprises said stamping mold, the mold also being configured to allow the addition of the thermoplastic polymer, in particular by overmolding or welding.

As a variant, the material supply device comprises another mold configured to carry out the supply of said at least one thermoplastic polymer, in particular by overmolding or welding.

Another subject of the invention, according to another of its aspects, in combination or not with what is defined above, is a heating process for the localized thermal activation of a predetermined zone of a composite part with a polymer matrix. thermoplastic, in particular implementing a heating device as defined above, the method comprising the following steps: a) Step a: positioning at a non-zero distance from the composite part a mask comprising at least one perforated zone, so as to at least partially superimposing said at least one perforated zone with said predetermined zone, b) Step b: heating, using a heating device with infrared emitter(s) separated from the composite part by said mask, through said at least one perforated zone, said predetermined zone of the composite part at a temperature greater than or equal to the melting temperature of the thermoplastic polymer, the other zones of the composite part being preserved from e the deconsolidation temperature of the thermoplastic polymer.

When the composite part comprises a substantially plane composite laminate, the mask can be arranged substantially parallel to such a plane of the composite part, at a predetermined distance between 5 mm and 40 mm, preferably between 5 mm and 20 mm, for example equal to 20 mm.

Step b can be controlled by a control member of the heating device according to a heating cycle, predetermined or adapted in particular according to the part composite, the heating cycle comprising in particular a heating ramp and a plateau, the duration of the heating cycle being preferably less than or equal to 3 min, in particular less than or equal to 2 min, more preferably less than or equal to 1 min 30 s , or even less than or equal to 1 min.

The heating device may comprise at least one temperature sensor, in which case the method advantageously comprises the step consisting in allowing the sending, by the temperature sensor, of at least one item of information relating to the temperature of said predetermined zone to the control member of the heating device, in particular a PID type regulation.

Another subject of the invention, according to another of its aspects, in combination with what is defined above, is a process for adding material allowing the localized addition of at least one thermoplastic polymer to a heated composite part of localized manner using the heating process as defined above, in particular using an installation as defined above, comprising the step consisting in carrying out the supply of said at least one thermoplastic polymer, in particular by overmolding or welding.

Said at least one thermoplastic polymer is preferably of the same nature as that of the matrix of the composite part or is at least compatible with the latter, being filled or not.

The thermoplastic polymer which is welded or overmolded on the composite part can be loaded so as to provide additional properties to the thermoplastic polymer alone. Such fillers may include, for example, short reinforcing fibers (carbon, glass or other) to improve the mechanical properties, fillers improving fire resistance, fillers improving the thermal and/or electrical conductivity of the polymer or even elastomeric fillers. to improve impact resistance properties or a mixture thereof.

The addition of material makes it possible to provide an additional function to the composite part, for example a fixing support, a stiffening rib, or any other function.

The addition of material may consist in forming a stiffening rib on the predetermined zone, after it has been heated, the width of the rib preferably being less than or equal to the width of the predetermined zone. Thanks to the invention, the added thermoplastic polymer comes to create adhesion with the composite part by the phenomenon of healing of the matrices in contact, improved with the heating described above. The invention makes it possible to locally thermally activate the composite part much better in terms of performance and reproducibility than in the prior art.

Brief description of the drawings

[Fig 1] Figure 1 schematically shows in perspective an example of a heating device according to the invention,

[Fig 2] figure 2 schematically represents a block diagram illustrating the steps of an example of a heating method according to the invention,

[Fig 3] Figure 3 represents a graph of the temperature as a function of time of an example of a heating cycle implemented using the apparatus of Figure 1,

[Fig 4] figure 4 schematically and partially represents the temperature gradients at the level of the predetermined heating zone in the composite part seen from the front after heating using the apparatus of figure 1,

[Fig 5] Figure 5 schematically shows the temperature gradients in the composite part seen in cross section after heating using the apparatus of Figure 1,

[Fig 6] Figure 6 shows in schematic cross section an example of an apparatus according to the invention,

[Fig 7] Figure 7 is a view similar to Figure 6 of another example of apparatus according to the invention,

[Fig 8] FIG. 7 schematically represents a block diagram illustrating the steps of an example of a process for supplying material according to the invention, and

[Fig 9] Figure 9 shows schematically and partially in front view the composite part of Figure 1 after implementation of the steps of the method of Figure 8.

detailed description

There is illustrated in FIG. 1 an example of a heating apparatus 1 for performing localized thermal activation of a predetermined zone Z of a composite part P with a thermoplastic polymer matrix, which is a PAEK in the example illustrated. The device 1 comprises a heating device 2 with infrared emitter(s). The device 1 also comprises a metal mask 3 comprising at least one perforated zone 4, in the example illustrated four slots together forming a square.

The mask 3 is arranged relative to the composite part P without contact with the latter and so as to superimpose along an axis Y substantially perpendicular to the plane of the mask, at least partially the or each perforated zone 4 with the predetermined zone P. As visible , the mask 3 is interposed between the composite part P and the heating device 2.

The device 1 further comprises a control member 5 of the heating device 2, shown in dotted lines in Figure 1.

According to the invention, the apparatus 1 is configured in order on the one hand to allow the localized thermal activation of the predetermined zone Z through the mask 3 at a temperature at least equal to the melting temperature T _f of the thermoplastic polymer and d on the other hand to preserve the other zones Za of the composite part P from the deconsolidation temperature of the composite part with a thermoplastic polymer matrix. The deconsolidation temperature of the composite part is approximately 310°C in this example, i.e. approximately 30°C below the melting temperature Tf of the matrix of the composite part P.

As can be seen, the mask 3 forms a metal sheet, in this example aluminum, and with a flat surface.

The composite part P has a flat shape in this example. It constitutes a composite laminate produced by superimposing plies of fibers pre-impregnated with the matrix consisting of the thermoplastic polymer, PAEK in this example.

In the example shown, the predetermined zone Z to be heated on the composite part P forms a square frame with four sides B of equal length. The sides B are extended slightly at the corners C of the frame. The perforated zone(s) 4, in this example the four slots 4, have the same geometry as the predetermined zone Z and therefore form between them a square frame, each perforated zone 4 forming one side of the square. In this example, the perforated areas 4 are made in the mask 3 by water jet cutting, but they can be made differently without departing from the scope of the invention.

Still in this example, the infrared emitters 6 of the heating device 2 are four in number arranged in a square, being formed of infrared lamps, each being cylindrical in shape, being bi-filaments with an 8-shaped section, all having in this example the same diameter and being of identical length. The infrared emitters 6 are arranged in a square in a plane parallel to the plane of the mask 3, perpendicular to the Y axis. Each infrared emitter 6 is arranged in a parallel manner, translated along the Y axis, with respect to one of the zones openwork 4 corresponding.

Fixing supports 7, extending parallel to the Y axis in this example, are provided between the heating device 2 and the mask 3, substantially at the corners of the square formed by the infrared emitters 6 and the perforated zones 4. Mounting brackets 7 are eight in number and hold each infrared emitter 6 close to its ends. In this example, the distance between the heating device 2 and the mask 3, in particular the perforated zones 4 of the mask 3 is fixed, being in this example equal to 30 mm.

It is within the scope of the invention if the distance between the heating device 2 and the mask 3 is adjustable.

The apparatus 1 further comprises a frame 10, part of which is visible in FIG. 1, making it possible to support the assembly formed by the mask 3 and the heating device 2. In this example, the frame 10 retains the mask 3 at one end upper of it.

The positioning of the apparatus 1 comprising the mask 3 and the heating device 2 relative to the composite part P is provided so as to allow the heating to the desired temperature of the predetermined zone Z through the perforated zones 4. In the example shown, this positioning can be adjusted using the frame 10. The distance between the mask 3 and the composite part P is in this example equal to 20 mm. The mask 3 and the composite part P are arranged parallel to each other. The mask 3 is arranged relative to the composite part P so that each perforated zone 4 is parallel, translated along the Y axis, with respect to one of the sides B of the square formed by the predetermined zone Z.

It should be noted that a metal casing can be provided which covers the whole of the heating device 2 on the infrared emitter side so that the energy is not dissipated towards the rear, opposite the mask 3, and that the radiation leaves as much as possible through the perforated zones 4. In the example illustrated, the device 1 comprises a temperature sensor 11 consisting of a pyrometer to measure the surface temperature of the composite part P at least in the predetermined zone Z.

The control member 5 is configured to control the heating device 2 according to a predetermined heating cycle, such as that which is illustrated in FIG. 3, comprising at least one temperature rise ramp R and a plateau E, the cycle of heating being planned to last less than 2 minutes. The temperature rise in the ramp of the cycle can be equal to 2° C./s for example. The duration of stage E can be between 10s and 30s, being 30s in the example shown. The duration of the temperature rise ramp R is in this example equal to 1 min 30 s.

The temperature sensor 11 is provided to provide information to the control unit 5 relating to the temperature at least in the predetermined zone Z and the control unit 5 can then regulate the power delivered to the infrared emitters in order to precisely follow the heating cycle based on this information.

It is sought to heat the predetermined zone Z above the melting temperature T _f of the matrix contained in the composite part P to be overmolded/welded in order to maximize the healing of the matrices in contact, but below the degradation temperature of the composite part P, in particular of the thermoplastic polymer of the composite part P. The principle of the invention, which is implemented by the apparatus 1, thus consists in heating only the predetermined zone Z to a temperature at which the thermoplastic matrices in contact will be able to weld together, typically higher than the melting temperature T _f of the thermoplastic polymer of the composite part P and that of the added material and not to heat beyond the deconsolidation temperature of the composite part P the remaining areas Za of the composite part P. In the example shown, with a PAEK matrix, the aim is to obtain the following temperatures:

- in the predetermined zone Z, a temperature greater than the melting temperature T _f and typically greater than or equal to T _f + 20°C (360°C), preferably greater than or equal to T _f + 60°C (390° VS).

- in the other zones Za, a temperature below the deconsolidation temperature of the composite part, that is to say less than or equal to approximately 310°C corresponding to T _{f −} 30°C. The surface heating power is between 100 and 500 kW/m ² , being chosen so as to allow rapid heating of the predetermined zone Z, being a function of the nature of the composite part P and/or of its thickness.

We will now describe various steps illustrated in Figure 2 of a heating method according to the invention using the apparatus of Figure 1.

The heating method aims to heat in a localized manner a predetermined zone Z of a composite part P with a thermoplastic polymer matrix, without deconsolidating the composite part P in the other zones Za. In the example illustrated, the heating method implements the heating apparatus 1 illustrated in Figure 1.

The method comprises a step 20 consisting in positioning the mask 3 at a non-zero distance from the composite part P so as to at least partially superimpose the perforated zones 4 with the predetermined zone Z, in this example by translation along the Y axis, perpendicular to the plane of the mask 3. As a variant, the heating device 1 can translate laterally or vertically to face the predetermined zone Z.

The next step 21 of the method consists in heating using the heating device 2 with infrared emitters 6, separated from the composite part P by the mask 3, through the perforated zones 4 the predetermined zone Z of the composite part P at a temperature greater than or equal to the melting point T _f of the thermoplastic polymer, the other zones Za of the composite part P being preserved from the deconsolidation temperature of the composite part with a thermoplastic polymer matrix.

The method may also include a preliminary step 19 consisting in programming the control member 5 of the heating device 2 according to a heating cycle that is predetermined or adapted according to the composite part P and the various parameters. Such a heating cycle can be as illustrated in FIG. 3 with the temperature of the predetermined zone Z as a function of time (in seconds), with a temperature rise ramp R and a plateau E. During the rise ramp at temperature R, the predetermined zone Z is heated at a heating rate of between 2° C./s and 10° C./s, 2° C./s for 90 s in this example. Stage E consists in maintaining, for example for a period equal to 30 s or even less, in particular less than 5 s, the temperature of the predetermined zone Z at the desired temperature, reached at the top of the temperature rise ramp R. The duration of the plateau E is preferably short to avoid remaining a long time at the temperature plateau because the thermal energy is then dissipated in the zones Za which could gradually lead to the deconsolidation of the composite part P. It is preferable to plan a heating cycle with the fastest possible heating and a very short soak time. As a variant, the heating cycle can comprise only a temperature rise ramp and no plateau.

The duration of the heating cycle in this example is less than 2 min as seen.

There is shown in Figure 4 the diagram of the temperature gradients reached at the bearing E on a part of the composite part P. The temperatures range between a maximum temperature T1 and a minimum temperature T7 with decreasing intermediate temperatures ranging from T2 to T6. In the example illustrated, the minimum temperature T7 is approximately 300°C. The temperature T6 is about 310°C. The temperature T5 is about 320°C. The temperature T4 is between 330° C. and 340° C., corresponding to the melting temperature T _f . The temperature T3 is between 350°C and 370°C. The temperature T2 is between 370 and 380°C while the temperature T1 is above 380°C. The width L of the predetermined zone Z is equal to 12 mm in this example. Thanks to the invention, the zone which is heated beyond the deconsolidation temperature of the composite part P, that is to say at 310° C., is limited to the single predetermined zone Z. In this example, the width of the perforated zones 4 is equal to 8 mm.

These temperatures T1 to T7 are found in Figure 5 in the thickness of the composite part P. The thickness of the composite part P is 2.5 mm in this example. In this figure, the zone heated to more than 350°C has been circled. It encompasses the predetermined zone Z and its periphery, as visible. The surface SI corresponds to the surface of the composite part P which faces the mask 3.

As can be seen in Figure 6, the mask 3 is cut internally for example using a water jet cut to form each perforated area 4. In the example illustrated in Figure 6, the area perforated 4 is of constant width h in the thickness of the mask 3. The radiation beam L emitted by the infrared emitter 6 which extends in a flared shape as far as the mask 3 is stopped by the latter, not crossing the mask 3 only in the zone occupied by the perforated zone 4 which lets it pass. At the exit of the perforated zone, again the beam L resumes a flared shape so that the zone of the composite part P which is affected by this radiation is wider than the width of the perforated zone 4. A width of perforated zones h equal to 8 mm will thus lead, for example, to a heating width h of 12 mm (which corresponds to the width of the deconsolidated zone), for a distance between mask 3 and composite part P of 20 mm and for a thickness of the mask of 5 mm.

There is shown in Figure 7 an alternative way of making the cutout of the mask 3 so as to form a chamfer in the thickness of the mask 3 at the level of the perforated zone 4 such that the width of the perforated zone 4 goes in narrowing from the side 31 of the mask facing the heating device 2 going towards the opposite side 32 of the mask 3 facing the composite part P. In this example, it can be seen that the flared shape of the beam F at the exit of the mask 3 going towards the composite part P has a width less than that of FIG. 6, due to this chamfer reducing the width of the perforated zone. For an initial width h of perforated zone 4 on side 31 of mask 3 equal to 8 mm which is reduced to a width U of perforated zone 4 on side 32 of mask 3 equal to 5 mm, a heating width h equal to 10 mm (which corresponds to the width of the deconsolidated zone), i.e. a width less than that, h , of the embodiment of figure 6.

There is shown in Figure 8 different steps of a material supply process allowing the localized supply, in particular by overmolding or welding, of at least one thermoplastic polymer on the composite part P heated in a localized manner using of the heating method described above with particular reference to Figure 2 and using the heating apparatus 1 illustrated in Figure 1.

The process for supplying material comprises step 40 of shaping in a mould, in particular stamping, of the composite part P passing from a flat 2D shape to a 3D shape in a first mould. It is not beyond the scope of the invention if this step 40 is not provided for in the method.

Next, in a step 41, the composite part P is demolded and positioned in a second mold.

In a subsequent step 42, the composite part P is locally heated to the desired temperature above the melting temperature of the thermoplastic polymer of the composite part P as explained above. Then, in a step 43, material is added, in this example overmoulding, for example by injection of a thermoplastic polymer, or local welding on the predetermined zone Z, for example in the form of a rib of stiffening.

The thermoplastic polymer used for the supply of material, in this example the overmolding is of the same nature as the thermoplastic polymer of the composite part P, in this example a PAEK, or at least corresponds to a thermoplastic polymer compatible with it .

There is no departing from the invention if steps 40 and 41 are carried out in a single step, simultaneously, within the same mold.

There is shown in FIG. 9 a part of the composite part P on which a stiffening rib 45 has been overmolded above the predetermined zone Z heated.

Thanks to the invention, the composite part P is locally heated to a temperature above the melting point of the thermoplastic polymer of the composite part P, such that only the predetermined localized zone Z is deconsolidated in order to make it possible to produce quality overmolding or welding with an added thermoplastic polymer in fusion, without deconsolidating the rest of the thermoplastic polymer matrix of the composite part P placed outside this predetermined zone Z.

In the example illustrated, for a width L of predetermined heated zone Z equal to 12 mm, the rib 45 has been molded having a width h of 4 mm.

The width L is greater than the width h in this example in particular to compensate for a possible bad positioning of the mask 3 with respect to the composite part P which could cause overmolding on a zone not thermally activated for example. Thanks to this difference in width, it is possible to ensure that the stiffening rib is actually overmoulded in the predetermined zone Z thermally activated and not next to it. In another embodiment, the width L may be less, being at least greater than or equal to the width of the rib 45 or of any other part to be overmolded/welded.

The thermoplastic polymer which is welded or overmolded on the composite part P can be loaded so as to provide additional properties to the thermoplastic polymer alone. Such fillers may include, for example, short reinforcing fibers (carbon, glass or other) to improve the mechanical properties, fillers improving fire resistance, fillers improving thermal conductivity and/or electric polymer or elastomeric fillers to improve the impact resistance properties or a mixture thereof.

As a variant, the thermoplastic polymer added by overmolding or welding is unfilled. The predetermined zone Z can be formed by a continuous zone as in the example illustrated, or discontinuous with zone portions not touching, of identical shapes to each other or not.

Claims

1. Heating apparatus (1) for carrying out localized thermal activation of a predetermined zone (Z) of a composite part (P) with a thermoplastic polymer matrix, comprising: a heating device (2) with infrared emitter(s) (6), a mask (3) comprising at least one perforated zone (4), the mask (3) being arranged relative to the composite part (P) without contact with the latter and so as to at least partially superimpose said at least one perforated zone (4) with said predetermined zone (Z), the mask (3) being interposed between the composite part (P) and the heating device (2), a control member (5) of the heating device ( 2), the apparatus (1) being configured in order on the one hand to allow the localized thermal activation of said predetermined zone (Z) through said mask (3) at a temperature at least equal to the melting temperature of the polymer thermoplastic, and on the other hand to preserve the other zones (Za) of the composite part (P) from the temperature ture of deconsolidation of the composite part (P) with a thermoplastic polymer matrix.

2. Apparatus (1) according to claim 1, the mask comprising a metal sheet.

3. Apparatus (1) according to any one of the preceding claims, wherein said at least one perforated zone (4) of the mask (3) has a shape or geometry similar to that of said predetermined zone (Z) of the composite part (P).

4. Apparatus (1) according to any one of the preceding claims, in which the or each perforated zone (4) has, at least on the side (32) of the mask (3) which faces the composite part (P), an area less than or equal to that of the corresponding predetermined zone (Z).

5. Apparatus (1) according to any one of the preceding claims, the relative positioning of the mask (3) and the heating device (2) and / or the positioning of this assembly of the mask (3) and the heating device ( 2) relative to the composite part (P) being provided so as to allow heating to the desired temperature of said predetermined zone (Z) through said at least one perforated zone (4).

6. Apparatus (1) according to any one of the preceding claims, the composite part (P) being substantially planar, in which the mask (3) is arranged substantially parallel to the composite part (P).

7. Apparatus (1) according to any one of the preceding claims, comprising at least one temperature sensor (11), in particular a pyrometer, configured to measure the surface temperature of the composite part (P), at least in said zone predetermined (Z).

8. Apparatus (1) according to any one of the preceding claims, wherein the control member (5) is configured to control the heating device (2) according to a heating cycle comprising at least one temperature rise ramp (R) and optionally a stage (E), the heating cycle preferably lasting less than or equal to 3 min, in particular less than or equal to 2 min, more preferably less than or equal to 1 min and 30 s, or even less than or equal to 1 min.

9. Installation for supplying material allowing the localized supply of at least one thermoplastic polymer, on a predetermined zone (Z) of a composite part (P), the installation comprising a heating device (1) according to the any one of the preceding claims and an apparatus for supplying material, in particular by overmolding or welding, to allow the supply of said at least one thermoplastic polymer, chosen to be compatible with the thermoplastic polymer of the composite part (P), in said predetermined area (Z) after heating the same with the heater (1).

10. Installation according to the preceding claim, comprising a mold arranged to support the composite part (P) during or after the localized thermal activation, said mold being a stamping mold for the 3D shaping of the composite part (P ) or an injection mold having a cavity for the composite part (P).

11. Heating method for the localized thermal activation of a predetermined zone (Z) of a composite part (P) with a thermoplastic polymer matrix, in particular implementing a heating apparatus (1) according to any one of claims 1 to 8, the method comprising the following steps:

(a) Step a: positioning at a non-zero distance from the composite part (P) a mask (3) comprising at least one perforated zone (4), so as to at least partially superimpose said at least one perforated zone (4) with said predetermined zone (Z), (b) Step b: heating, using a heating device (2) with an infrared emitter(s) (6) separated from the composite part (P) by said mask (3), through said au at least one perforated zone (4), said predetermined zone (Z) of the composite part (P) at a temperature greater than or equal to the melting point of the thermoplastic polymer of the composite part (P), the other zones (Za) of the composite part (P) being preserved from the deconsolidation temperature of the composite part (P) with a thermoplastic polymer matrix.

12. Method according to the preceding claim, in which step b is controlled by a control member (5) of the heating device (2) according to a heating cycle that is predetermined or adapted in particular according to the composite part (P), the heating cycle comprising in particular a temperature rise ramp (R) and a plateau (E), the duration of the heating cycle being preferably less than or equal to 3 min, in particular less than or equal to 2 min, preferably even less or equal to 1 min 30s.

13. Process for supplying material allowing the localized supply of at least one thermoplastic polymer to a composite part (P) heated in a localized manner using the heating process according to one of claims 11 and 12, in particular using an installation according to claim 9 or 10, comprising the step consisting in carrying out the addition of said at least one thermoplastic polymer, in particular by overmolding or welding.

14. Method according to the preceding claim, said at least one thermoplastic polymer being of the same nature as that of the matrix of the composite part or being at least compatible with the latter, being filled or not.