METHOD FOR ASSEMBLING A FIRST METAL PART WITH A SECOND PART MADE OF AN ORGANIC MATRIX COMPOSITE MATERIAL AND PART MADE FROM SUCH AN ARRANGEMENT

Description

Technical Field

[0001] This presentation concerns a method for assembling two parts of a component, one part being metallic and the other being made of an organic matrix composite material. For example, such a component could be a rocket engine combustion chamber casing, but not exclusively. Previous technique

[0002] Methods for joining a metallic part to a part made of an organic matrix composite material are known. However, these joining methods are very often improvable. Therefore, there is a need for improvements. GB 2 550 966 A describes a joining method using in-situ formed fasteners. EP 3 498 410 A1 describes a joining structure. EP 3 159 525 A1 describes a propulsion chamber and a manufacturing method. US 5 570 573 A describes a combustion chamber for a propellant with a leak-proof connection between an end wall and a composite tubular structure. Description of the invention

[0003] One embodiment relates to a method for assembling a first metallic part with a second part made of an organic matrix composite material, the first part having a first connecting portion and the second part having a second connecting portion, the method comprising the steps of: overlap the first and second fitting portions, a through hole in the second fitting portion opening into the first fitting portion, the through hole having a side wall, form a protective layer at least on the side wall of the through hole, form a seal between the protective layer and the first fitting portion, and form by additive manufacturing by cold gas-entrained metal powder deposition, also known by the acronym CGS for " Cold Gaz Spraying "In English, a fastener extending into the through hole, fixed to the first portion of the fitting, and clamping the second portion of the fitting.

[0004] It is understood that the connecting portion of a part is the portion that is configured to be in contact and cooperate directly with the other part. Thus, a portion of a part that does not cooperate with the other part, for example, that is not superimposed on, or does not overlap, the connecting portion of the other part, is not part of the connecting portion of said part.

[0005] It is also understood that the second connecting portion has one or more through holes. Hereafter, and unless otherwise specified, "the through hole" means "at least one through hole." According to one variation, the hole is formed upstream of the process implementation, with the second connecting portion having the through hole before the two connecting portions overlap. According to a second variation, the second connecting portion does not have a through hole upstream of the process implementation, the through hole being formed during an intermediate step after the two connecting portions overlap. In this case, a blind hole may also be formed in the first connecting portion during this intermediate step, but not necessarily. It is understood that a blind hole is a hole with only one opening and a concave shape.Such a blind hole improves the grip of the fastener on the first section of the connection. In the case of a blind hole, the protective layer can, for example, also extend onto the lateral walls of the blind hole, and a seal can be formed between the protective layer and the bottom of the blind hole.

[0006] It is understood that additive manufacturing by cold gas-driven metal powder deposition is a manufacturing method where the metal is deposited at a temperature below its melting point. This deposition method is particularly well-suited to the assembly of the second part because it ensures that the metal temperature during deposition remains below the deterioration temperature of the organic matrix composite material of the second part. Hereafter, and unless otherwise specified, "CGS deposition" refers to "additive manufacturing by cold gas-driven metal powder deposition."

[0007] For example, the fastener may be made of the same metal as the first part, but not necessarily. The fastener partially or completely encloses the second portion of the fitting. In other words, the second portion of the fitting is sandwiched, in whole or in part, between the fastener and the first portion of the fitting. The fastener can have various shapes. For example, it can be shaped like a pin, a bridge, an annular flange, etc.

[0008] It is understood that the protective layer is a layer that protects the second part during the CGS deposition of the fastener. It is understood that the sealing gasket creates a watertight seal between the protective layer and the first portion of the fitting. Naturally, at least a portion of the surface of the first portion of the fitting remains uncovered (i.e., not covered by the sealing gasket or the protective layer) from the through hole so that the fastener can be formed directly on this uncovered surface, thus securing the fastener to the first portion of the fitting. Hereafter, and unless otherwise specified, "gasket" refers to "sealing gasket."

[0009] The inventors observed that during the formation of the fastener by CGS deposition, in prior art processes such as that described in document GB 2 550 966 A, some of the sprayed material could escape between the first and second sections of the fitting. This leads, on the one hand, to abrasion of the second section (the escaping metal particles attacking the composite material of the second section), and on the other hand, to defects in the fastener, particularly at the interface between the fastener and the first section of the fitting. The inventors found that this weakens the mechanical strength of the assembly.

[0010] By creating a seal between the protective layer and the first section of the fitting, the material sprayed during the CGS deposition process can no longer escape. This allows the fastener to be formed flawlessly at its junction with the first section of the fitting, without damaging the second section. The mechanical strength of the assembly is significantly improved compared to assemblies produced using prior art processes.

[0011] For example, the parts can be plates, flat or curved, and the fastening portions can form flanges, flat or curved.

[0012] For example, the first and second parts each form a plate extending in a first and a second direction, and having a thickness in a third direction perpendicular to the first and second directions. The first and second parts are arranged side by side in the first direction, with at least one through hole extending in the third direction. The first and second connecting portions overlap in the first and second directions. The first and / or second direction may be straight or curved, similar to directions defined in a Cartesian, cylindrical, or spherical coordinate system.

[0013] In some embodiments, the protective layer extends over the entire interface between the second connecting portion and the fastener element.

[0014] For example, the fastener can interact with the second part on surfaces other than the lateral surface of the hole. In this case, a protective layer as defined above allows the second part to be perfectly protected on all surfaces configured to interact with the fastener during the formation of the fastener.

[0015] In some embodiments, the protective layer is formed using a metallic sheet.

[0016] For example, the metal sheet, initially flat, is applied to the second fitting section and then deformed to conform to the shape of all or part of the second fitting section, particularly the side wall of the hole. For example, the metal sheet is then machined, for instance by milling, to allow free access to the bottom of the hole, i.e., to the first fitting section. For example, the metal sheet is made of a metal that is more easily plastically deformed than the material of the first and / or second fitting section. For example, the metal sheet is gold, silver, aluminum, copper, etc.

[0017] In some embodiments, the sealing joint between the metal sheet and the first portion of the fitting is formed by metal deposition using additive manufacturing by wire arc metal deposition or " metal arc wire " in English.

[0018] Unless otherwise specified, the term "arc-wire deposition" hereafter refers to "additive manufacturing by arc-wire metal deposition." This type of deposition is very gentle on the substrate, both thermally and in terms of abrasion, and is particularly well-suited for the secondary component and the metal layer. This ensures the integrity of both the metal layer and the secondary component, ultimately guaranteeing the strength of the assembly.

[0019] An arc-wire deposit allows for direct application of soft metal, making it easy to fill gaps / spaces and form a robust and reliable seal.

[0020] For example, the arc-wire coating covers all the walls of the hole, including the bottom. A portion of the bottom of the hole is then machined, for example by milling, to allow free access to the bottom of the hole, i.e., to the first section of the fitting, while preserving a portion of the arc-wire coating extending from the metal foil to the first section of the fitting. This portion forms the sealing gasket. For example, the metal of the arc-wire coating may be the same as the metal of the metal foil, but not necessarily. This can allow for satisfactory adhesion between the metal foil and the arc-wire coating.

[0021] In some embodiments, the protective layer and the sealing joint are formed simultaneously by at least one metallic deposit of the type additive manufacturing by wire arc metal deposition or " metal arc wire " in English.

[0022] Forming the protective layer and the seal in a single step saves time. Furthermore, reducing the number of steps also reduces the number of interventions and therefore the risk of damaging the first and / or second section of the connection.

[0023] In some embodiments, the protective layer and the sealing joint are formed simultaneously by at least two metallic deposits, a first deposit being a metallic deposit of the type additive manufacturing by metal arc-wire deposition, and a second deposit being a deposit by projection of metallic powder entrained by a cold gas made on the first deposit, the second deposit being separate from the additive manufacturing step by projection of metallic powder entrained by a cold gas to form the fixing element.

[0024] In other words, the protective layer and the gasket are formed in at least two passes: at least one first pass by arc-wire deposition and at least one second pass by continuous surface deposition (CSG). For example, the metal from the first and second deposits is removed from the bottom of the hole (while leaving a portion forming the seal between the first and second fitting sections) before forming the fastener. In other words, the gasket and the protective layer can, in this example, form a single continuous element. For example, the same material, such as copper, is used for both the first and second deposits, but this is not necessarily the case. For example, in the case of a rotationally symmetrical part, the first and / or second layer can be a circumferential continuous surface deposition.

[0025] An embodiment relates to a method for manufacturing a rocket engine combustion chamber casing comprising the assembly method according to any one of the embodiments described in this presentation.

[0026] The assembly process described herein is particularly well suited for the manufacture of rocket engine combustion chamber casings.

[0027] An embodiment relates to a part comprising a first metallic part and a second part made of organic matrix composite material assembled together by the assembly process according to any of the embodiments described in this presentation. Brief description of the drawings

[0028] The purpose and advantages of this presentation will be better understood upon reading the detailed description below of various embodiments given as non-limiting examples. This description refers to the attached figure pages, on which: [ Fig. 1 ] There figure 1 represents the first step in the assembly process. Fig. 2A-2B ] THE figures 2A et 2B represent two variants of the assembly process, respectively. Fig. 3A-3B ] THE figures 3A et 3B represent a second step in the assembly process, respectively for the two variants of figures 2A et 2B , according to a first embodiment. [ Fig. 4A-4B ] THE figures 4A et 4B represent a third step in the assembly process, respectively for the two variants of figures 2A et 2B , according to the first embodiment. [ Fig. 5A-5B ] THE figures 5A et 5B represent a fourth step in the assembly process, respectively for the two variants of figures 2A et 2B , according to the first embodiment. [ Fig. 6A-6D ] THE figures 6A, 6B, 6C et 6D represent three intermediate steps respectively for simultaneously creating the protective layer and the seal, for the two variants of the figures 2A et 2B , according to a second embodiment. [ Fig. 7A-7B ] THE figures 7A et 7B represent a fifth step in the assembly process, respectively for the two variants of figures 2A et 2B . [ Fig. 8 ] There figure 8 represents an external casing of a rocket engine combustion chamber, obtained using the assembly process according to the first or second embodiment. Fig. 9 ] There figure 9 represents a rocket engine equipped with the outer casing of the rocket engine combustion chamber of the figure 8 . Description of the implementation methods

[0029] For the sake of clarity in this presentation, it should be noted that the views in the figures are highly schematic. The assembly process of a first metallic part 12 with a second part 14 made of an organic matrix composite material is described with reference to the figures 1 à 7 For example, the first part 12 is made of a metallic alloy, for example a nickel-based alloy, while the second part 14 is made of an organic matrix composite material of the thermoplastic or thermosetting type. It should be noted that the figures 2A, 2B , 3A, 3B , 4A, 4B, 5A, 5B , 6C et 6D are cross-sectional views according to plane II of the figure 1 The first and second stages of figures 1, 2A et 2B , as well as the fifth stage of the figures 7A et 7B are common to the first and second embodiments, figures 3A, 3B , 4A, 4B, 5A et 5B being specific to the first embodiment, while the figures 6A, 6B, 6C et 6D are specific to the second embodiment.

[0030] In this example, the first and second parts, 12 and 14, are rotationally symmetric parts. More specifically, the first and second parts, 12 and 14, each have an essentially annular plate shape extending along an axial direction X (axis of rotational symmetry), a radial direction R, and a circumferential direction C. The radial direction R is perpendicular to the X-axis. The azimuthal or circumferential direction C corresponds to the direction describing a ring around the axial direction X. The three directions—axial, radial, and azimuthal—correspond respectively to the directions defined by the ridge, radius, and angle in a cylindrical coordinate system.

[0031] The first part presents a first connecting portion 12A comprising a shoulder 12C. The shoulder 12C extends transversely to the axial direction X. In other words, in this example, the shoulder 12C extends along the radial direction R and circumferential direction C. The first connecting portion 12A thus forms a step receiving a second connecting portion 14A from the second part 14.

[0032] During the first stage shown on the figure 1 , we bring the first and second parts 12 and 14 together along the axial direction X, as indicated by the arrows I, until the second part 14 cooperates against the shoulder 12C, so as to overlap the first portion of the fitting 12A and the second portion of the fitting 14A.

[0033] According to a first variant shown on the figure 2A The second fitting portion 14A is provided with at least one through hole 14B before the first step. The through hole 14B extends in the radial direction R and opens onto the first fitting portion 12A. In this example, the through hole 14B is frustoconical in shape, with the lateral wall 14B3 being uniformly inclined with respect to the axis Att, forming a convergent point in the radial direction towards the first fitting portion 12A. Any other shape of through hole is conceivable. In this example, the first fitting portion 12A does not have a blind hole, but could include a blind hole, formed before the first step, or after the first step as described below with reference to the second variant of the figure 2B .

[0034] According to a second variant shown on the figure 2B The second portion of the fitting 14A has no through hole before the first step. At least one through hole 14B is formed after the first step, for example, using a drill bit F. In this example, when drilling the through hole 14B in the second portion of the fitting 14A, a blind hole 12B is also drilled in the first portion of the fitting 12A, extending from the through hole 14B. The through hole 14B and the blind hole 12B extend in the radial direction R. The through hole 14B is similar to the one described with reference to the figure 2A The blind hole 12B has a geometric axis Atb extending radially between an inlet 12B1 and a bottom 12B2, and a side wall 12B3 extending between the inlet 12B1 and the bottom 12B2. In this example, the blind hole 12B is frustoconical in shape, with the side wall 12B3 uniformly inclined with respect to the axis Atb, forming a convergent line from the inlet 12B1 to the bottom 12B2. Any other blind hole shape is conceivable. In one variant, the blind hole 12B is present before the first stage, but the through hole 14B is not.

[0035] A protective layer 18 is then formed on the lateral wall 14B3 of the through hole 14B. The protective layer 18 can, for example, be formed according to the first embodiment or according to the second embodiment described below.

[0036] According to the first embodiment, for example, during a second step, as shown in the figures 3A et 3B , a metal sheet 18A on the second portion of fitting 14A, opposite the first portion of fitting 12A, and then the metal sheet 18A is stamped so that it fits the walls of hole 14B ( figure 3A , first variant) or the walls of holes 14B and 12B ( figure 3B (second variant). On the figures 2A et 2B The stamped 18A metal sheet is represented by dashed lines. In this example, the 18A sheet is made of copper.

[0037] Subsequently, in a third step, the portion of the 18B metal sheet extending over the bottom of the hole is machined, in this example by milling, as shown in the diagram. figures 4A et 4B , so as to reveal the first portion of fitting 12A at the bottom of the holes. In other words, after machining, the 14B2 / 12B2 bottoms of the holes are formed by the first portion of fitting 12A. On the figures 4A et 4B The machined and removed parts of the 18A metal sheet are represented in dashed lines.

[0038] On the figure 4A The first section of fitting 12A does not have a blind hole (see first variant) and the protective layer 18 extends over the entire radial height of the through hole 14B, up to the first section of fitting 12A. On the figure 4B the first portion of fitting 12A has a blind hole 12B (cf second variant) and the protective layer 18 extends over the entire radial height of the through hole 14B and the blind hole 12B, up to the bottom 12B2 of the blind hole 12B.

[0039] Next, in a fourth step, a sealing joint 19 is formed between the protective layer 18 and the first portion of the fitting 12A, as shown in the figures 5A (first variant) and 5B (second variant). In this example, the joint 19A is formed by arc-wire deposition, the joint 19A between the metal sheet 18A and the first part of the fitting 12A. In this example, the metal used to form the joint is copper or a copper-based alloy.

[0040] With the arc-wire coating covering the bottom 14B2 / 12B2 of the holes, the arc-wire coating is then machined, similarly to the third step above, to expose the first portion of the fitting 12A at the bottom of the holes, taking care not to damage the seal 19A extending between the metal sheet 18A and the first portion of the fitting 18A. For example, the diameter of the cutter used for this step is smaller than that of the cutter used for the third step. On the figures 5A et 5B The machined and removed parts of the arc-wire deposit are represented by dashed lines.

[0041] According to the second embodiment, represented on the figures 6A, 6B, 6C et 6D , the protective layer 18 and a joint 19B are formed simultaneously by arc-wire deposition. More precisely, in this example, a first arc-wire deposition is carried out along the circumferential direction C, forming one or more annular bands 18B1 according to the desired axial width, as shown in the figure 6A This first deposit 18B1 is, in this example, made of copper. The lateral walls 14B3 of the through holes 14B are coated along their entire radial height. In this example, the surface of the first visible portion of the fitting 12A through the through holes 14B is also coated. A second CGS deposit is then made along the circumferential direction C, forming one or more annular bands 18B2 of the desired axial width, partially covering, in this example, the circumferential bands 18B1. The annular band 18B2 extends over the entire outer periphery along the circumferential direction C of the second portion of the fitting 14A, as shown in the figure. figure 6B by covering the lateral walls 14B3 of the through holes 14B along their entire radial height. In this example, the surface of the first visible portion of the fitting 12A through the through holes 14B, covered by the strip 18B1, is also covered by the strip 18B2. The second coating 18B2 is copper in this example. According to an alternative, the annular strip 18B2 completely covers the axial strips 18B1. In this second embodiment, the protective layer 18 is therefore formed by a coating layer 18B, resulting from the strips 18B1 and 18B2. By forming such strips, the protective layer 18 also extends to the vicinity of the through hole 14B, opposite the first portion of the fitting 12A. During both arc-wire and CGS deposition to form the annular strips, a sealing joint 19B is simultaneously created between layer 18B and the first portion of the joint 12A, as shown in the figures 6C (first variant) and 6D (second variant). Indeed, the protective layer 18B is formed in contact with the first portion of the fitting 12A. Similar to the first embodiment, the portion of layer 18B that extends over the bottom of the hole is then machined, in this example by milling, as shown in the diagrams. figures 6C et 6D , so as to reveal the first portion of fitting 12A at the bottom of the holes. In other words, the bottoms 14B2 / 12B2 of the holes are formed by the first portion of fitting 12A. During this operation, care is taken not to alter portion 19B, which forms the joint. On the figures 6C et 6D The machined and removed parts are represented by dashed lines.

[0042] Finally, in a fifth step common to the first and second embodiments, a fixing element 20 is formed by CGS deposition, as shown in the figures 7A (first variant) and 7B (second variant). For example, the fastening element 20 is made of a metal alloy, for example, a nickel-based alloy. The fastening element 20 extends through the through hole 14B, is fixed to the first portion of the fitting 12A (i.e., on the ends 14B2, 12B2), and, together with the first portion of the fitting 12A, clamps the second portion of the fitting 14A. In particular, it is noted that the fastening element 20 clamps the second portion of the fitting 14A, notably via the side wall 14B3 of the through hole 14B, which is inclined with respect to the axis Att of the through hole 14B. In other words, the side wall 14B3 forms a seat for the fastener 20 which allows the first part 12 to be fixed to the second part 14. In this example, the interface between the fastener 20 and the second portion of the fitting 14A extends in the vicinity of the through hole 14B, this vicinity being part of the seat cooperating with the fastener 20.The fastening element 20 also clamps the second fastening portion 14A in this vicinity. According to one variant, there are as many point fastening elements as there are holes through 14B. According to another variant (not shown), a single fastening element forms an annular flange extending all around the second connecting portion 14A in the circumferential direction C and through all the holes through 14B. According to yet another variant (not shown), the fastening element forms a bridge fixed to the first part 12 on one side to the first connecting portion 12A via the through hole of the second connecting portion (14A) and on the other side to a portion of the first part other than the first connecting portion 12A (for example, the portion of the first part 12 on the left of the . figures 7A et 7B ).

[0043] There figure 8 represents part 10 resulting from the assembly described above. In this example, there are as many fasteners 20 as there are through holes. In this example, part 10 is a rocket engine combustion chamber casing. The assembly process described above is part of a manufacturing process for a rocket engine combustion chamber casing in this example.

[0044] There figure 9 represents a rocket engine 100 comprising the combustion chamber casing 10 opening onto an ejection nozzle 30.

[0045] Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various embodiments illustrated / mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims

1. A method for assembling a first metal part (12) with a second part (14) made of an organic matrix composite material, the first part (12) having a first connecting portion (12A) and the second part (14) having a second connecting portion (14B), the method comprising the steps of: - causing the first connecting portion (12A) and the second connecting portion (14A) to overlap, a through-hole (14B) of the second connecting portion (14A) opening onto the first connecting portion (21A), the through-hole (14B) having a side wall (14B3), characterized in that the method comprises the steps of: - forming a protective layer (18) at least on the side wall (14B3) of the through-hole (14B), - forming a seal (19A, 19B) between the protective layer (18) and the first connecting portion (12A), and - forming, by additive manufacturing using cold gas spray deposition of metal powder, a fastening element (20) which extends into the through-hole (14B), fastened to the first connecting portion (12A) and enclosing the second connecting portion (12B).

2. The assembly method according to claim 1, wherein the protective layer (18) extends over the entire interface between the second connecting portion (14A) and the fastening element (20).

3. The assembly method according to claim 1 or 2, wherein the protective layer (18) is formed using a metal sheet (18A).

4. The assembly method according to claim 3, wherein the seal (19A) is formed between the metal sheet and the first connecting portion by metal disposition by metal arc wire additive manufacturing.

5. The assembly method according to claim 1 or 2, wherein the protective layer (18) and the seal (19B) are formed simultaneously by at least one metal deposition by metal arc wire additive manufacturing.

6. The assembly method according to claim 5, wherein the protective layer (18) and the seal (19B) are formed simultaneously by at least two metal depositions, a first deposition (18B1) being a metal deposition by metal arc wire additive manufacturing, and a second deposition (18B2) being a cold gas spray deposition of metal powder carried out on the first deposition (18B1), the second deposition being distinct from the step of additive manufacturing using cold gas spray deposition of metal powder, in order to form the fastening element (20).

7. The method for manufacturing a rocket engine combustion chamber jacket (10) comprising the assembly method according to any one of claims 1 to 6.

8. A piece comprising a first metal part (12) and a second part (14) made of organic matrix composite material assembled together by the assembly method according to any one of claims 1 to 6.