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

Abstract

The invention relates to 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 and the second connecting portion to overlap, a through-hole (14B) of the second connecting portion opening onto the first connecting portion, - forming a protective layer (18) on the side wall (14B3) of the through-hole, - forming a seal (19A) between the protective layer and the first connecting portion, and - forming, by additive manufacturing using spray deposition of metal powder driven by a cold gas, a fastening element (20) which extends into the through-hole, is fastened to the first connecting portion and encloses the second connecting portion.

Description

Method for assembling a first metallic part with a second part made of an organic matrix composite material, and the part resulting from such an assembly 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 assembly methods are very often improvable. Therefore, there is a need for improvement in this area. 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: - to overlap the first and second sections of the fitting, with a through hole in the second section opening into the first section of the fitting, the through hole having a lateral wall, - to form a protective layer at least on the side wall of the through hole, - to form a watertight seal between the protective layer and the first section of the connection, and - formed by additive manufacturing by deposition of metal powder propelled by a cold gas, also known by the acronym CGS for "Cold "Gas Spraying" in English, a fastening element 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" will be used. means "additive manufacturing by deposition by projection of metallic powder entrained by a cold gas".

[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, using prior art processes, 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 forming a seal between the protective layer and the first section of the fitting, the material sprayed during the CGS deposition can no longer escape, so that the fastener can be formed without defects at its joint with the first section of the fitting, and without damaging the second section of the connection. The mechanical strength of the assembly is significantly improved compared to assemblies obtained 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 fastening 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 portion and then deformed to conform to the shape of all or part of the second fitting portion, 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 portion. 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 portion of the fitting. For example, the metal sheet is a sheet of 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 of the type of additive manufacturing by metal arc-wire 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 metal arc-wire 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, one the first deposit being a metallic deposit of the type additive manufacturing by arc-wire metal deposition, and a second deposit being a deposit by cold gas-driven metal powder projection carried out on the first deposit, the second deposit being separate from the additive manufacturing step by cold gas-driven metal powder projection 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 different implementation methods. given as non-limiting examples. This description refers to the attached figure pages, on which:

[0029] [Fig. 1] Figure 1 represents a first step in the assembly process.

[0030] [Fig. 2A-2B] Figures 2A and 2B represent two variants of the assembly process respectively.

[0031] [Fig. 3A-3B] Figures 3A and 3B represent a second step in the assembly process, respectively for the two variants of Figures 2A and 2B, according to a first embodiment.

[0032] [Fig. 4A-4B] Figures 4A and 4B represent a third step in the assembly process, respectively for the two variants of Figures 2A and 2B, according to the first embodiment.

[0033] [Fig. 5A-5B] Figures 5A and 5B represent a fourth step in the assembly process, respectively for the two variants of Figures 2A and 2B, according to the first embodiment.

[0034] [Fig. 6A-6D] Figures 6A, 6B, 6C and 6D represent respectively three intermediate steps to simultaneously produce the protective layer and the sealing joint, respectively for the two variants of Figures 2A and 2B, according to a second embodiment.

[0035] [Fig. 7A-7B] Figures 7A and 7B represent a fifth step in the assembly process, respectively for the two variants of Figures 2A and 2B.

[0036] [Fig. 8] Figure 8 represents an external casing of a rocket engine combustion chamber, obtained using the assembly process according to the first or second embodiment.

[0037] [Fig. 9] Figure 9 represents a rocket engine equipped with the outer casing of the rocket engine combustion chamber from Figure 8. Description of the implementation methods

[0038] For clarity, 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 Figures 1 to 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 is noted that figures 2A, 2B, 3A, 3B, 4A, 4B, 5A, 5B, 6C and 6D are cross-sectional views along plane II of figure 1. The first and second steps of figures 1, 2A and 2B, as well as the fifth step of figures 7A and 7B, are common to the first and second embodiments, figures 3A, 3B, 4A, 4B, 5A and 5B being specific to the first embodiment while figures 6A, 6B, 6C and 6D are specific to the second embodiment.

[0039] 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.

[0040] 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.

[0041] In the first step shown in Figure 1, the first and second parts 12 and 14 are brought together along the axial direction X, as shown by arrows I, until the second part 14 cooperates against the shoulder 12C, so as to overlap the first portion of the connecting 12A and the second portion of the connecting 14A.

[0042] According to a first variant shown in Figure 2A, the second fitting portion 14A has 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, with the lateral wall 14B3 being uniformly inclined with respect to the axis Att, converging in the radial direction towards the first fitting portion 12A. Any other shape of through hole is possible. 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 in Figure 2B.

[0043] According to a second variant shown in 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 Figure 2A. The blind hole 12B has a geometric axis Atb which extends in the radial direction between an inlet 12B1 and a bottom 12B2, and has a lateral 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 section from the inlet 12B1 to the bottom 12B2. Any other shape of blind hole is conceivable. In one variant, the blind hole 12B is present before the first stage, but not the through hole 14B.

[0044] 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.

[0045] According to the first embodiment, in a second step, as shown in Figures 3A and 3B, a metal sheet 18A is placed on the second portion of the fitting 14A, opposite the first portion of the fitting 12A, and the metal sheet 18A is then pressed so that it conforms to the walls of the hole 14B (Figure 3A, first variant) or to the walls of holes 14B and 12B (Figure 3B, second variant). In Figures 2A and 2B, the pressed metal sheet 18A is shown with dashed lines. In this example, the sheet 18A is made of copper.

[0046] Subsequently, in a third step, the portion of the metal sheet 18B extending over the bottom of the hole is machined, in this example by milling, as shown in Figures 4A and 4B, so as to expose the first portion of the fitting 12A at the bottom of the holes. In other words, after machining, the bottoms 14B2 / 12B2 of the holes are formed by the first portion of the fitting 12A. In Figures 4A and 4B, the machined and removed portions of the metal sheet 18A are shown as dashed lines.

[0047] In Figure 4A, the first portion of the 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 portion of the fitting 12A. In Figure 4B, the first portion of the fitting 12A has a blind hole 12B (see 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.

[0048] Next, in a fourth step, a seal 19 is formed between the protective layer 18 and the first portion of the fitting 12A, as shown in Figures 5A (first variant) and 5B (second variant). In this example, the seal 19A is formed by arc-wire deposition between the metal foil 18A and the first portion of the fitting 12A. In this example, the metal used to form the seal is copper or a copper-based alloy.

[0049] 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. In Figures 5A and 5B, the machined and removed portions of the arc-wire coating are shown as dashed lines.

[0050] According to the second embodiment, shown in Figures 6A, 6B, 6C, and 6D, the protective layer 18 and a joint 19B are formed simultaneously by arc-wire deposition. More specifically, in this example, a first arc-wire deposition is carried out in the circumferential direction C, forming one or more annular bands 18B1 with the desired axial width, as shown in Figure 6A. This first deposit 18B1 is made of copper in this example. The lateral walls 14B3 of the through holes 14B are coated along their entire radial height. In this example, the surface of the first portion of the fitting 12A visible through the through holes 14B is also coated. A second arc-wire deposition is then carried out in the circumferential direction C, forming one or more annular bands 18B2 with the desired axial width, partially covering, in this example, the circumferential bands 18B1.The annular strip 18B2 extends over the entire outer periphery along the circumferential direction C of the second connecting portion 14A, as shown in Figure 6B, covering the lateral walls 14B3 of the through holes 14B along their entire radial height. In this example, the surface of the first connecting portion 12A visible 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. In an alternative embodiment, 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 bands, 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 depositions to form the annular bands, a sealing joint. 19B is formed simultaneously between layer 18B and the first portion of the fitting 12A, as shown in Figures 6C (first variant) and 6D (second variant). 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 extending over the bottom of the hole is then machined, in this example by milling, as shown in Figures 6C and 6D, so as to expose the first portion of the 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 the fitting 12A. During this operation, care is taken not to alter the portion 19B that forms the seal. In Figures 6C and 6D, the machined and removed portions are shown with dashed lines.

[0051] Finally, in a fifth step common to the first and second embodiments, a fastening element 20 is formed by CGS deposition, as shown in 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 should be noted that the fastening element 20 clamps the second portion of the fitting 14A, notably via the lateral 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 fixing element 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 connecting portion 14A extends in the vicinity of the through hole 14B, this vicinity forming part of the seat cooperating with the fastener 20. The fastener 20 also clamps the second connecting portion 14A in this vicinity. In one variant, there are as many point fasteners as there are through holes 14B. In another variant (not shown), a single fastener forming an annular flange extends all around the second connecting portion 14A in the circumferential direction C and through all the through holes 14B. In yet another variant... variant (not shown), the fixing element forms a bridge fixed to the first part 12 on one side on the first portion of fitting 12A via the through hole of the second portion of fitting (14A) and on the other side on a portion of the first part other than the first portion of fitting 12A (for example the portion of the first part 12 on the left in figures 7A and 7B).

[0052] Figure 8 shows 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, in this example, part of a manufacturing process for a rocket engine combustion chamber casing.

[0053] Figure 9 represents a rocket engine 100 comprising the combustion chamber casing 10 opening onto an ejection nozzle 30.

[0054] 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.

[0055] It is also evident that all the characteristics described with reference to a process are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a process.

Claims

Demands

1. A method for assembling a first metallic 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: - to overlap the first connecting portion (12A) and the second connecting portion (14A), a through hole (14B) of the second connecting portion (14A) opening onto the first connecting portion (21A), the through hole (14B) having a lateral wall (14B3), - to form a protective layer (18) at least on the side wall (14B3) of the through hole (14B), - to form a seal (19A, 19B) between the protective layer (18) and the first portion of the connection (12A), and - to form by additive manufacturing by deposition by projection of metallic powder entrained by a cold gas a fastening element (20) extending in the through hole (14B), fixed on the first portion of fitting (12A), and enclosing the second portion of fitting (12B).

2. 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. Assembly method according to claim 1 or 2, wherein the protective layer (18) is formed using a metal foil (ISA).

4. Assembly method according to claim 3, wherein the sealing joint (19A) is formed between the metal sheet and the first portion of the fitting by metal deposition of the type additive manufacturing by arc-wire metal deposition.

5. An assembly method according to claim 1 or 2, wherein the protective layer (18) and the joint are formed simultaneously sealing (19B) by at least one metallic deposit of the type additive manufacturing by metal arc-wire deposition.

6. Assembly method according to claim 5, the protective layer (18) and the sealing gasket (19B) are formed simultaneously by at least two metal deposits, a first deposit (18B1) being a metal deposit of the type additive manufacturing by wire arc metal deposition, and a second deposit (18B2) being a deposit by cold gas-entrained metal powder projection made on the first deposit (18B1), the second deposit being separate from the additive manufacturing step by cold gas-entrained metal powder projection to form the fastening element (20).

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

8. A part comprising a first metallic 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.