Manufacture of at least one portion of an object, corresponding assembly tool, method for controlling the tool, and resulting objects

Abstract

The invention relates to a method for manufacturing a thermoplastic-material portion of an object, this portion being intended to be assembled by resistance butt welding to a complementary thermoplastic-material portion of this object, comprising the following steps: a) providing an object portion made of thermoplastic material or additively manufacturing an object portion from thermoplastic material, which contains from 5% to 15% by volume of carbon fibres; and b) depositing, by additive manufacturing, a continuous carbon-fibre pattern onto the portion of step a), following a layout corresponding to the area intended to be heated during the assembly by resistance butt welding of the portion to the complementary portion and such that a voltage can be applied to two opposite ends of the continuous pattern during the assembly. The invention also relates to a corresponding assembly tool and a corresponding control method and to resulting objects.

Description

[0001] Description

[0002] Title: Manufacturing of at least one part of an object, corresponding assembly tool, method of controlling the tool and resulting objects

[0003] FIELD OF THE INVENTION

[0004]

[0001] The invention relates to a method for manufacturing a structure that can be implemented in space and a structure obtained by this method. The invention also relates to a machine for manufacturing such a structure.

[0005] STATE OF THE ART

[0006]

[0002] It is common to send and position space objects, such as satellites, antenna reflectors or optical mirrors, in space.

[0007]

[0003] The size and configuration of this type of object are very constrained by the launch conditions and in particular the characteristic dimensions of a launcher fairing.

[0008]

[0004] In addition, to be able to withstand the very severe mechanical, acoustic and thermodynamic constraints of a launch, structures are now oversized. This creates an increase in cost and mass that we are trying to avoid.

[0009]

[0005] In order to overcome these constraints, research efforts are being carried out to develop systems for manufacturing and assembling structures in space.

[0010]

[0006] For example, patent application US2017 / 0036783 discloses a solution for manufacturing structures in space based on the technique of additive manufacturing (or 3D printing) of thermoplastic materials, possibly reinforced with carbon fibers.

[0011]

[0007] According to this document, several material bonding mechanisms can be implemented within the framework of this additive manufacturing. These include fused deposition modeling and welding, and more particularly resistance welding.

[0012]

[0008] This latter technique has the advantage of being able to be used to weld composite materials reinforced by carbon fibers and of not imposing any major constraints in terms of size and geometry of the parts that can be welded.

[0013]

[0009] As taught for example by patent application WO2015 / 166227, it nevertheless requires the interposition of an interstitial part in the junction zone between the two components to be welded, in order to be able to melt the two components there by heating the interstitial part by applying a voltage to it. The installation of such a part is not easy on Earth, because it must be positioned very precisely at the location of the zone of the component to be heated, but obviously proves even more complicated to implement in space, in particular due to the absence of gravity.

[0014] PRESENTATION OF THE INVENTION

[0015]

[0010] The invention aims to at least partially overcome the drawbacks of the prior art.

[0011] For this purpose, the invention proposes a method for manufacturing at least one part of an object, made of thermoplastic material and intended to be assembled by resistance welding to a complementary part of this object, made of thermoplastic material, comprising the steps of: a) providing at least one part of the object made of thermoplastic material or producing by additive manufacturing at least one part of the object from thermoplastic material, the thermoplastic material containing from 5 to 15% by volume of carbon fibers; and b) depositing by additive manufacturing at least one continuous pattern of carbon fiber on said at least one part of step a), according to an implantation corresponding to the area intended to be heated during the assembly by resistance welding of said at least one part to the complementary part and so as to be able to apply a voltage to two opposite ends of the continuous pattern during said assembly.

[0016]

[0012] Thanks to these arrangements, additive manufacturing is not only used to very precisely position an interstitial part or component and thus very precisely delimit the welding / assembly zone (here one or more continuous carbon fiber patterns), but also to permanently fix it or them at the location of the heating zone.

[0013] These arrangements also have the advantage of being able to benefit from the installation of one or more continuous carbon fiber patterns as interstitial parts or components to reinforce the part thus produced. This is particularly interesting for space applications where vibrations can activate the vibration modes of the corresponding object part.

[0017]

[0014] Furthermore, carbon fibers have a low coefficient of thermal expansion, which is also beneficial in the space field, where benefiting from near insensitivity to the effects of thermal gradients is important.

[0018]

[0015] This method also proves useful in a terrestrial environment, particularly because it allows the interstitial part or component to be positioned very precisely.

[0019]

[0016] It will also be noted that it can be implemented to repair objects, complete them or reinforce them, both on Earth and in space and that it can be fully automated due to its simplicity of implementation. This latter characteristic is particularly interesting for manufacturing, assembly and maintenance processes in orbit where all tasks are automated with robotic means due to the lack of accessibility.

[0017] Advantageously, but optionally, the manufacturing method according to the invention can further comprise at least one of the following characteristics: the thermoplastic material contains 10% by volume of carbon fibers; the carbon fibers are short fibers having a length of 0.1 to 1 mm; the thermoplastic material is polyetherketoneketone (PEKK), polyetheretherketone (PEEK), low melting polyaryletherketone (LM-PAEK) and, preferably, polyetherketoneketone (PEKK);the deposition of the or each continuous carbon fiber pattern comprises the deposition of a carbon fiber prepreg impregnated with a thermoplastic material selected from polyetherketoneketone (PEKK), polyetheretherketone (PEEK) and low-melting polyaryletherketone (LM-PAEK), preferably polyetherketoneketone (PEKK); the prepreg is a mixture of at most 60% by volume, preferably 60% by volume, of continuous carbon fibers and at least 40% by volume of polyetherketoneketone (PEKK); the prepreg is in the form of a ribbon; the or at least one continuous carbon fiber pattern is made from a yarn formed from a plurality of continuous carbon fibers braided together or from a plurality of unidirectional continuous carbon fibers;step a) comprises the production by additive manufacturing of the complementary part of the object from thermoplastic material and a positioning imprint in this complementary part of a jaw used for clamping the two parts of the object against each other during assembly by resistance welding; step a) comprises the production by additive manufacturing from thermoplastic material of the two parts of the object, with on each part of the object a positioning imprint of the part of the object, of a shape complementary to the shape of the imprint of the complementary part, so that the two imprints cooperate by complementary shapes during said assembly by resistance welding;step a) comprises the production by additive manufacturing of the complementary object part from thermoplastic material and with at least one martyr protuberance, each configured to follow a continuous carbon fiber pattern and to come into contact with this continuous carbon fiber pattern before applying the resistance welding; the manufacturing method further comprises a step of assembling the two object parts by resistance welding by clamping the two parts against each other and applying a tension between the two ends of the or each continuous carbon fiber pattern; the assembly step takes place in space and the additive manufacturing step(s) before assembly, on Earth or in space.

[0018] Advantageously, step a) comprises the deposition by additive manufacturing of an alternation of layers of thermoplastic material and at least one continuous carbon fiber.;

[0020]

[0019] This alternation of layers makes it possible to provide, on the one hand, the part of the object produced with the method according to the invention, with rigidity thanks to the carbon fiber(s) while benefiting from its(their) low sensitivity to the thermal gradient due to its(their) low coefficient of thermal expansion (in addition of course to the formation of the resistance welding pattern) and, on the other hand, inter-layer cohesion thanks to the thermoplastic material.

[0020] The invention also relates to a part of an object or an object, in particular a space object, obtained by implementing the method as defined above. The space object is for example a satellite, an antenna reflector, an optical mirror or a satellite link structure of a satellite constellation.

[0021]

[0021] The manufacturing method according to the invention makes it possible to manufacture a structure, a part of the structure of such a space object and more generally all or part of an object intended to be used in space or on Earth (such as, for example, a part of a motor vehicle).

[0022]

[0022] Another object of the invention is a resistance welding assembly tool, in particular for implementing the assembly step as defined above, comprising two jaws configured to clamp two parts to be assembled against each other, at least two electrical contact elements arranged at the periphery of one of the two jaws so as to be able to apply a voltage between the opposite ends of at least one continuous pattern of carbon fiber carried by one of the two parts and a voltage source supplying the two electrical contact elements, the electrical contact elements being mounted in translation on a support of one of the two jaws, each by means of an axis secured to the support and carrying a compression spring interposed between the electrical contact element and this support.

[0023]

[0023] According to specific provisions of this tool, which can be combined: the jaws are each mounted on one of the branches of a robotic gripper, if necessary via the support; the assembly tool further comprises a remote communication interface adapted to receive control instructions from the ground.

[0024]

[0024] The invention also relates to a space object, in particular a satellite, comprising an assembly tool as defined above and optionally an additive manufacturing machine.

[0025]

[0025] The invention also relates to a method for controlling from the ground an assembly tool and, where appropriate, an additive manufacturing machine, comprising sending to the assembly tool and, where appropriate, to the additive manufacturing machine, a sequence of instructions configured for implementing the method as defined above.

[0026] DESCRIPTION OF FIGURES

[0027]

[0026] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings, in which: Figure 1 schematically represents a machine for assembling by resistance welding two portions of a structure, according to an embodiment of the invention, which is mounted on a satellite according to this embodiment; Figures 2a and 2b are respectively top and bottom views on a larger scale of detail II of Figure 1; Figure 3 schematically represents a part of the structure with a variant of a continuous carbon fiber pattern; Figure 4 schematically represents the main steps of the manufacturing method according to an embodiment of the invention;and figures 5a, 5b, 5c schematically represent positioning imprints of the object parts, according to an alternative embodiment of the invention.;

[0028] DETAILED DESCRIPTION OF THE INVENTION

[0029]

[0027] A method of manufacturing a structure 10, such as that shown in FIG. 1, will now be described with reference to these figures. This is a framework of a space object, such as for example a reflector consisting of two sub-structures 10a, 10b each produced by additive manufacturing then assembled to each other by resistance welding, using the manufacturing method according to the invention.

[0030]

[0028] This method therefore firstly comprises a step 100 of producing each of these sub-structures 10a, 10b by additive manufacturing from thermoplastic material.

[0031]

[0029] Advantageously, the thermoplastic material is a thermoplastic material reinforced with carbon fibers. Advantageously, for reasons of manufacturing convenience, the carbon fibers of this type of material are cut or ground carbon fibers, commonly called short fibers. Their length is generally 0.1 to 1 mm, here of the order of 0.1 - 0.5 mm, as observed by micrometric cutting of the material.

[0032]

[0030] This is for example a thread comprising 90% by volume of polyetherketone ketone (PEKK) as thermoplastic material and 10% by volume of short carbon fibers, such as in particular the PEKK Carbon Gray filament marketed by the company Kimya.

[0033]

[0031] The manufacturing method according to the invention comprises a second step 200 of depositing by additive manufacturing at least one continuous pattern of carbon fiber on the part or parts of one of the sub-structures 10a, 10b produced in step 100, intended to be assembled to one or more respective complementary parts of the other sub-structure produced in step 100, by resistance welding during a subsequent step of this manufacturing method, described below.

[0034]

[0032] Alternatively, it is possible to distribute carbon fiber patterns over parts of the two substructures 10a, 10b.

[0035]

[0033] Each continuous carbon fiber pattern deposited as a final pattern layer is intended to serve as an interstitial component between the parts of the substructures 10a, 10b to be assembled by resistance welding. It in fact forms an electrical conductor equivalent to a resistance when an electric current passes through it and, therefore, will dissipate thermal energy capable of melting the thermoplastic material of the parts of substructures 10a, 10b to be assembled, with a view to welding them to each other.

[0036]

[0034] For this purpose, each continuous carbon fiber pattern is deposited according to an implantation corresponding to the zone intended to be heated during assembly by resistance welding and so as to be able to be consequently put under tension during this assembly.

[0037]

[0035] In the case of the embodiment illustrated in Figures 1, 2a and 2b, two carbon fiber patterns 11a, 11b are successively deposited on a part 12 of the lower substructure 10b (here a part of a base triangle of the reflector), parallel to each other and following a general U-shaped configuration. Other configurations and number of patterns are of course conceivable depending on the assembly to be carried out. An example of another configuration 11' produced on a part 12' of a substructure similar to part 12 is shown in Figure 3.

[0038]

[0036] This U is partially housed in a hollow 13 (see figure 1) produced by additive manufacturing during the first step 100 of the manufacturing process, in order to delimit a positioning imprint of the complementary part 18 of substructure 10a intended to be assembled to the part 12. The pressure applied during the assembly step by resistance welding described in more detail below, being concentrated on this hollow 13, the latter in practice also delimits the material melting zone during this assembly. Here too, various forms of imprints can be produced as needed depending on the assembly to be carried out.

[0039]

[0037] The ends 14a-14d of each of the patterns 11a, 11b also protrude from the central zone 15 of the part 12 so as to be able to be put under tension during assembly by resistance welding. These ends 14a-14d are for this purpose left exposed on support arms 16a, 16b projecting from the central zone, as is each of the patterns 11a, 11b in the part of the central zone 15 where pressure is applied during the assembly step by resistance welding, for optimal heat transfer. For the rest, the patterns 11a, 11b are covered with a layer of thermoplastic material, in order to anchor them to the underlying thermoplastic material. Alternatively, the end sections of the patterns 11a, 11b may be flush with the surface of the part 12 or the ends 14a-14d may be made accessible by one or more passages provided in the part 12.

[0040]

[0038] It will be observed in this regard that the carbon fiber patterns 11a, 11b have been shown seen in transparency in figures 1, 2a (partially) and 2b (totally).

[0041]

[0039] Advantageously, for reasons of manufacturing convenience, the deposition of each carbon fiber pattern 11a, 11b comprises the deposition of a carbon fiber pre-impregnated with a thermoplastic material, preferably polyetherketoneketone (PEKK). This carbon fiber pre-impregnated, commonly called a carbon fiber prepreg, is for example a mixture of 60% by volume of continuous carbon fibers and 40% by volume of polyetherketoneketone (PEKK). A high proportion of continuous fibers is in this respect favorable to the mechanical and thermoelastic properties of the pre-impregnated.

[0042]

[0040] This proportion of continuous carbon fibers ensures the presence of bare continuous carbon fibers at the above-mentioned locations (electrical contact and heat transfer) of the interstitial component layer, despite the presence of thermoplastic impregnation material.

[0043]

[0041] In the field of composite materials, continuous fibers are understood to mean fibers having a length greater than 50 mm. Depending on the part to be manufactured, fibers having an intermediate dimension between short and continuous fibers, i.e. having a length of between 1 and 50 mm and called long fibers in this field, can also be used.

[0044]

[0042] Preferably, the prepreg comprises a plurality of unidirectional fibers.

[0045]

[0043] Each carbon fiber in the case of the present embodiment is also presented, for example, in the form of a thread grouping together several thousand elementary filaments (typically from 3,000 to 48,000) measuring, for example, from 6 to 10 μm in diameter. This type of fiber is known under the name of rovings.

[0046]

[0044] A pattern of continuous carbon fibers, in the form of a pre-impregnated material or not, can also, as a variant, be organized in a different manner, for example in the form of a thread of fibers braided together, a textile obtained by weaving strands, or even a mat (non-woven sheet of loose fibers).

[0047]

[0045] The pre-impregnated material is in practice in the form of a ribbon, for example 1 mm wide and 0.2 mm thick.

[0048]

[0046] Preferably, the first additive manufacturing step 100 comprises the deposition by additive manufacturing of an alternation of layers of thermoplastic material (here PEKK reinforced with carbon fibers) and of carbon fibers (here the carbon fiber pre-impregnated). In other words, one or more continuous carbon fibers are interposed between layers of thermoplastic material, in addition to the one(s) forming the layer serving as interstitial component(s).

[0049]

[0047] This alternation of layers makes it possible, as mentioned above, to provide, on the one hand, to the part of the substructure produced with the method according to the invention, rigidity thanks to the carbon fiber(s) of the pre-impregnated while benefiting from its(their) low sensitivity to the thermal gradient due to its(their) low coefficient of thermal expansion (in addition of course to the formation of the resistance welding pattern) and, on the other hand, inter-layer cohesion thanks to the thermoplastic material.

[0050]

[0048] Furthermore, the presence of short carbon fibers not only makes it possible to reinforce the thermoplastic material with structural elements, but also to bring the coefficient of thermal expansion of this material and that of the prepreg closer together. If they are too far apart, this in fact induces high internal stresses in the assembly after cooling of the manufactured part of the object. In other words, the thermoplastic material filled with short carbon fibers must have a coefficient of thermal expansion as close as possible to the material filled with continuous carbon fibers, otherwise, when the part cools, the two materials do not compress each other as much and high shear stresses can be induced in the part. It is therefore recommended to have between 5 and 15% by volume of short fibers in the first thermoplastic material.

[0051]

[0049] To manufacture parts of objects or less resistant objects it is nevertheless possible, as a variant, not to implement such an alternation, or even not to reinforce the thermoplastic material at all.

[0052]

[0050] Alternatively, the first additive manufacturing step can be carried out separately from that of depositing the continuous carbon fiber pattern(s).

[0053]

[0051] In the case of the present embodiment, additive manufacturing takes place on Earth, while the assembly of the parts thus produced takes place in space after having been brought there by a launcher.

[0054]

[0052] By "in space" is meant the part of the universe located beyond the Earth's atmosphere.

[0055]

[0053] The additive manufacturing machine used to produce these two substructures, commonly called a 3D printer, is in the case of the present embodiment a commercially available manufacturing machine, such as for example that marketed by the company 9TLabs under the reference Red Series Build Module (RSBM).

[0056]

[0054] Such a machine is capable of depositing molten wire of thermoplastic material reinforced with carbon fibers as well as a molten ribbon of carbon fiber pre-impregnation.

[0057]

[0055] Alternatively, the additive manufacturing machine may comprise a multi-axis robot for depositing the wire and the ribbon and a laser for melting the latter, such as for example that marketed by the company Coriolis under the reference Coriolis C1.

[0056] In the case of the implementation of an existing part made of thermoplastic material, reinforced or not with carbon fibers, it is sufficient to use a commercial manufacturing machine which is capable of depositing carbon fiber.

[0058]

[0057] In other embodiments, additive manufacturing also takes place in space, in which case additive manufacturing machines adapted to this environment are implemented. This is for example a machine of the type described in the patent application US2017 / 0036783 mentioned above, in the patent application US2015 / 0075732 or in the patent application WO2015 / 060923. Where appropriate, they are adapted to be able to deposit wire and ribbon, in the manner of those commercially available and identified above for additive manufacturing on Earth.

[0059]

[0058] The method according to the present embodiment further comprises a third step 300 of assembling in space the two sub-structures 10a and 10b by resistance welding by clamping against each other the two parts of the sub-structures 10a, 10b intended to be welded to each other and by applying a tension between the two ends of the or each continuous pattern 11a, 11b of carbon fiber. There is thus a duality of mechanical force and electrical tension (and therefore heat treatment).

[0060]

[0059] For this purpose, there is provided, as illustrated in Figure 1 and for a part 12 to be assembled different from that of Figures 2a and 2b, an assembly tool 20 by resistance welding comprising two jaws 21a, 21b configured to clamp the two parts to be welded against each other, at least two electrical contact elements, only one of which is visible in Figure 1 and bears the numerical reference 22, arranged on either side of one of the two jaws 21a, 21b, here the jaw 21a, to apply a tension between the ends of the or each continuous pattern of carbon fiber, and a tension source, not visible in Figure 1 because here housed in a housing 23 of a robotic gripper 24. This housing 23 is also used for mounting the assembly tool 20 on a robotic arm 31 of a satellite structure 30, both shown very schematically in Figure 1.

[0061]

[0060] This voltage source is nevertheless shown schematically in Figures 2a and 2b and bears the numerical reference 25.

[0062]

[0061] The jaws 21 a, 21 b are each mounted on one of the branches 26a, 26b of the robotic gripper 24 by means of a support 27a, 27b made of thermally and electrically insulating material.

[0063]

[0062] The electrical contact elements 22 are in the case of the present embodiment in the form of rectangular parallelepipeds, for example made of copper, each mounted on one of the two supports 27a, 27b.

[0064]

[0063] Each electrical contact element 22 is advantageously mounted in translation on the support 27a, 27b, by means of axes 28 integral with the latter and carrying a compression spring 29 interposed between the electrical contact element 22 and this support 27a, 27b, for the benefit of optimal electrical contact with the ends 14a-14d of the continuous carbon fiber pattern(s), thanks to the elastic stress exerted by the springs 29.

[0065]

[0064] It will also be observed that each support 27a, 27b has, for mounting the electrical contact elements 22, at least in part a generally stirrup-shaped cross-section, the branches of which extend on either side of the associated jaw 21a, 21b and carry, for one of the two supports 27a, 27b, here the support 27a, the electrical contact elements 22.

[0066]

[0065] Furthermore, a hollow 17 is also made in the part 18 of the substructure 10a complementary to the part 12 of the substructure 10b, by additive manufacturing during the first step 100 of the manufacturing method, in order to delimit a positioning imprint of the jaw 21a of the resistance welding tool 20, that is to say that located between the two electrical contact elements 22. This imprint 17 serves to have a good positioning of the jaw 21a relative to the part 18 to be welded and thus in particular to compensate for the uncertainties of positioning of the resistance welding tool 20 when the latter is in the form of a robot, at the time of its approach to the part 18, and above all to guarantee that the two electrical contact elements 22 of the resistance welding tool 20 properly contact the bare fibers of the part 12.For this purpose, the imprint 17 has a base 17a whose shape and dimensions correspond to the shape and dimensions of the jaw 21a (here a U) and a top 17b which widens to guide the jaw 21a towards the base 17a.

[0067]

[0066] Alternatively, the flare 17b may, for example, be replaced by a chamfer.

[0068]

[0067] Returning to the hollow 13 visible in FIG. 1, this is also bordered by a rounded portion 19 to guide an imprint of the part 18, of a shape complementary to that of the hollow 13, towards the latter.

[0069]

[0068] Alternatively, as shown in Figures 5a to 5c, other shapes of male / female positioning imprints may be provided, so that the 12” and 18” parts cooperate by complementarity of shapes of their imprints in order to guarantee good positioning before the resistance welding comes to guarantee the maintenance in position. Here, the complementary shapes of the imprints have a trapezoidal cross-section. Other polygonal or curved shapes are of course also conceivable here.

[0070]

[0069] As can also be seen in these figures 5a to 5c, a martyr protuberance 41 can also be provided, that is to say a protuberance which is subsequently sacrificed, on the area of ​​the complementary part 18” (male) which is welded onto the continuous pattern 11” of carbon fiber of the female part 12”. This protuberance 41 follows the pattern 11”.

[0071]

[0070] In fact, when the carbon fiber(s) of the pattern 11” are under tension and very hot, it is necessary to be sure that they will come into contact with the complementary part 18” and that contact is not missed because of a small asperity outside the pattern 11”. As the martyr protuberance 41 (preferably of small thickness, i.e. approximately 0.2 to 0.4 mm, like the thickness of the carbon fiber) on the complementary part 18” (made of thermoplastic material advantageously reinforced with short fibers) follows the pattern 11” of carbon fiber, it makes it possible to ensure contact at this precise location where the heat density is the greatest (see figure 5b). Once this martyr protuberance 41 has melted, it spreads and flattens out in order to guarantee a good weld of the two parts 12” and 18”, and the two flat surfaces of these male / female parts 12”, 18” are in good contact, as initially planned (see figure 5c).

[0072]

[0071] The assembly tool 20 is advantageously autonomous or controllable from the ground to allow remote implementation of the manufacturing method described above. In this regard, the assembly tool preferably comprises a control unit comprising a computer, a memory, and a communication interface with the ground, preferably comprising an antenna for transmitting and receiving radio waves. This control unit is housed in the housing 23 and therefore not visible in FIG. 1, with the exception of the communication interface 28, which partially projects therefrom in the case of the present embodiment.

[0072] The communication interface is adapted to receive control instructions from the tool, said instructions being processed by the computer for implementing the method.The computer is adapted to control the operation of the tool components according to the control instructions received to implement the method. Thus, the tool can be controlled remotely for the manufacture of an object in space, by sending instructions to the tool from a ground control center.

[0073]

[0073] Preferably, the assembly tool 20 is advantageously energy-autonomous, to eliminate any power supply cable. In this respect, it may comprise a battery and / or one or more photovoltaic sensors (not shown).

[0074]

[0074] When additive manufacturing takes place in space, one or more articulated arms (not shown) may also be provided on the outer wall of the satellite to grasp and move the substructures produced by additive manufacturing from the manufacturing machine to the assembly tool 20.

[0075]

[0075] In practice, the assembly by resistance welding with this assembly tool 20 is carried out as follows (see also FIG. 1, where the continuous patterns 11 a, 11 b of carbon fiber are shown visible by transparency):

[0076] • The two substructures 10a, 10b are placed between the jaws 21a, 21b and in contact at the level of their parts to be welded to each other;

[0077] • Pressure is applied by the jaws 21 a, 21 b to ensure contact and good welding; • The voltage source 24 comes into contact with the two ends of patterns 11 a, 11 b constituting the welding pattern, via the electrical contact elements 22;

[0078] • The source 24 is energized to allow current to pass through the carbon fiber patterns 11a, 11b so that they heat up;

[0079] • The material melts and mixes between the two parts to be joined for a few minutes after reaching the melting temperature (in the case of this embodiment between 350°C and 400°C);

[0080] • The power supply is cut off and the material cools;

[0081] • Once below the glass transition temperature, the pressure is released and the assembly is complete.

[0082]

[0076] Many other variants are possible depending on the circumstances and it is recalled in this regard that the present invention is not limited to the examples shown and described.

Claims

Claims 1. Method for manufacturing at least one part of an object, made of thermoplastic material and intended to be assembled by resistance welding to a complementary part of this object, made of thermoplastic material, comprising the steps of: a) providing at least one part of the object made of thermoplastic material or producing by additive manufacturing at least one part of the object from thermoplastic material, the thermoplastic material containing from 5 to 15% by volume of carbon fibers; and b) depositing by additive manufacturing at least one continuous pattern of carbon fiber on said at least one part of step a), following an implantation corresponding to the area intended to be heated during the assembly by resistance welding of said at least one part to the complementary part and so as to be able to apply a tension to two opposite ends of the continuous pattern during said assembly.

2. The method of claim 1, wherein the thermoplastic material contains 10% by volume of carbon fibers.

3. A method according to claim 1 or 2, wherein the carbon fibers of the thermoplastic material are short fibers having a length of 0.1 to 1 mm.

4. A method according to any one of the preceding claims, wherein the thermoplastic material is polyetherketoneketone (PEKK), polyetheretherketone (PEEK), low melting polyaryletherketone (LM-PAEK) and, preferably, polyetherketoneketone (PEKK).

5. A method according to any one of the preceding claims, wherein the deposition of the or each continuous carbon fiber pattern comprises the deposition of a carbon fiber prepreg impregnated with a thermoplastic material selected from polyetherketoneketone (PEKK), polyetheretherketone (PEEK) and low melting polyaryletherketone (LM-PAEK), preferably polyetherketoneketone (PEKK).

6. The method of claim 5, wherein the prepreg is a mixture of at most 60% by volume, preferably 60% by volume, continuous carbon fibers and at least 40% by volume polyetherketoneketone (PEKK).

7. Method according to any one of the preceding claims, in which step a) comprises the production by additive manufacturing of the complementary part of the object from thermoplastic material and of a positioning imprint in this complementary part of a jaw used for clamping the two parts of the object against each other during assembly by resistance welding.

8. Method according to any one of the preceding claims, in which step a) comprises the production by additive manufacturing from thermoplastic material of the two parts of the object, with on each part of the object a positioning imprint of the part of an object, of a shape complementary to the shape of the imprint of the complementary part, so that the two imprints cooperate by complementarities of shapes during said assembly by resistance welding.

9. Method according to any one of the preceding claims, in which step a) comprises the production by additive manufacturing of the complementary part of object from thermoplastic material and with at least one martyr protuberance, each configured to follow a continuous pattern of carbon fiber and to come into contact with this continuous pattern of carbon fiber before applying the resistance welding.

10. A method according to any preceding claim, further comprising a step of assembling the two object parts by resistance welding by clamping the two parts against each other and applying tension between the two ends of the or each continuous carbon fiber pattern.

11. Method according to claim 10, in which the assembly step takes place in space and the additive manufacturing step(s) before assembly, on earth or in space.

12. Method according to any one of the preceding claims, in which step a) comprises the deposition by additive manufacturing of an alternation of layers of thermoplastic material and at least one continuous carbon fiber.

13. Part of an object (12) or object (10), in particular a spatial object, obtained by implementing the method according to one of the preceding claims.

14. Assembly tool (20) by resistance welding, in particular for implementing the assembly step of claim 10 or 11, characterized in that it comprises two jaws (21 a, 21 b) configured to clamp two parts to be assembled against each other, at least two electrical contact elements (22) arranged at the periphery of one of the two jaws so as to be able to apply a tension between the opposite ends of at least one continuous pattern of carbon fiber carried by one of the two parts, and a voltage source (25) supplying the electrical contact elements, and in that the electrical contact elements are mounted in translation on a support of one of the two jaws, each by means of an axis (28) integral with the support and carrying a compression spring (29) interposed between the electrical contact element and this support.

15. Tool according to claim 14, characterized in that the jaws are each mounted on one of the branches (26a, 26b) of a robotic gripper (24), where appropriate via the support.

16. Tool according to one of claims 14 and 15, characterized in that it further comprises a remote communication interface (28) adapted to receive control instructions from the ground.

17. Space object, in particular satellite (30), comprising an assembly tool according to one of claims 14 to 16 and optionally an additive manufacturing machine.

18. Method for controlling from the ground an assembly tool according to one of claims 14 to 16 and, where appropriate, an additive manufacturing machine, comprising sending to the assembly tool and, where appropriate, to the additive manufacturing machine, a sequence of instructions configured for implementing the method according to one of claims 1 to 12.

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