FR3153280A1 - Composite aeronautical part comprising an overmolded portion - Google Patents

Abstract

Aeronautical part (10) comprising a body (11) made of composite material which has a portion that is at least partially impregnated with a thermoplastic-type impregnation material (30) and a protective element (34, 44) comprising a thermoplastic-type construction material which is added by overmolding onto the portion. Method for manufacturing such a part. Figure for abstract: Figure 10

Description

Composite aeronautical part comprising an overmolded portion

The invention relates to an aeronautical part such as a turbomachine blade such as for example an industrial gas turbine, an aeronautical turbine of an aircraft or helicopter engine, or an auxiliary power unit (APU). The invention applies in particular to fan, turbine and OGV rectifier blades.

STATE OF THE PRIOR ART

In a turbojet engine, marked 1 in the FIG. 1 , the air is admitted into an inlet sleeve 2 to pass through a blower 3 before splitting into a central primary flow and a secondary flow surrounding the primary flow.

The primary flow is compressed by low pressure 4 and high pressure 5 compressors before reaching a combustion chamber 6, after which it expands by passing through a high pressure turbine 7 and a low pressure turbine 8, before being evacuated, generating auxiliary thrust. The secondary flow is propelled directly by the fan to generate main thrust.

Each turbine 7, 8, as well as the fan 3, comprises crowns of blades oriented radially and regularly spaced around an axis of rotation AX, an external casing 9 surrounding the crowns of blades.

Each blade 10 carries a blade 12. The blade 12 comprises a body 11 made of composite material. The blade 10 comprises a root P by which it is mounted to a cell of a rotating disk of the turbojet engine. The root P is extended by a blade 12 extending in a main direction EV, called the span direction. This blade 12 is the aerodynamic part of this blade, and it is terminated by a tip. It comprises a leading edge 13 substantially parallel to the span direction EV and located upstream AM, relative to the direction of circulation of the gases in the turbomachine and a trailing edge 14 substantially parallel to the leading edge 13 and spaced from it along the axis AX to be downstream AV of the blade. The blade 12 is terminated by a tip S. A metal leading edge element 15 is attached by gluing to the leading edge 13 in order to improve its resistance to shocks and abrasion. Assembling by gluing is prohibited for the production of critical aeronautical parts and the production of the leading edge element in metal limits the possibility of acting on its geometry to improve its performance. Finally, such a leading edge element adds mass to a part moving at high speed.

Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various carbon emission restrictions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new aircraft types and those already in operation, requiring the implementation of technological solutions to ensure their compliance with current regulations. Civil aviation has been mobilizing for several years now to contribute to the fight against climate change.

Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental consequences with the aim of improving the energy efficiency of aircraft.

Consequently, the Applicant is constantly working to reduce its negative climate impact by using methods and operating virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

This sustained research and development work focuses on new generations of aircraft engines, the weight reduction of aircraft, particularly through the materials used and lighter on-board equipment, the development of the use of electrical technologies to ensure propulsion, and, as an essential complement to technological progress, aeronautical biofuels.

To this end, the invention is the result of technological research aimed at very significantly improving the performance of aircraft and, in this sense, contributes to reducing the environmental impact of aircraft. For this purpose, the invention relates to an aeronautical part comprising a body made of composite material which has a portion which is at least partially impregnated with a thermoplastic-type impregnation material and a protective element comprising a thermoplastic-type construction material which is added by overmolding to the portion.

This results in a part with improved durability that has a lightweight body made of thermosetting resin composite, a portion of which is reinforced with a protective element made of a lightweight, strong and economical material to shape. Overmolding the protective element improves durability and allows this type of reinforcement to be extended to parts, such as blades, which are considered critical. Finally, thermoplastic injection allows the protective element to perfectly match the contour of the part and ensure a reliable connection regardless of the geometry of the part when an added part may have shape tolerances that are detrimental to assembly (by gluing for example).

For the purposes of this application, an aeronautical part is a part which is implemented in an aircraft and which is generally subject to normative safety requirements. The invention applies more particularly to composite engine parts having an aerodynamic profile.

• la pièce aéronautique est une pale de turbomachine comprenant un corps de pale en matériau composite s’étendant selon une direction principale, le corps ayant un intrados et un extrados reliés en une partie amont du corps par un bord d’attaque et en une partie aval du corps d’autre part par un bord de fuite, les parties amont et aval étant situées de part et d’autre de la direction principale. La portion qui est au moins partiellement imprégnée d’un matériau d’imprégnation de type thermoplastique la portion qui est au moins partiellement imprégnée d’un matériau d’imprégnation de type thermoplastique est une portion d’un bord choisi parmi le bord d’attaque et le bord de fuite ;

According to other particular, non-exclusive and optional embodiments of the invention:

• the aeronautical part is a turbomachine blade comprising a blade body made of composite material extending in a main direction, the body having a lower surface and an upper surface connected in an upstream part of the body by a leading edge and in a downstream part of the body on the other hand by a trailing edge, the upstream and downstream parts being located on either side of the main direction. The portion which is at least partially impregnated with a thermoplastic type impregnation material the portion which is at least partially impregnated with a thermoplastic type impregnation material is a portion of an edge chosen from the leading edge and the trailing edge;

- the protective element has serrations;

- the impregnation material is chosen from the following types of materials: Polyetherimide, Polyetheretherketone, Polyetherketone;

- the leading edge portion has a thickness substantially equal to a strand of a fiber of the composite material;

- the trailing edge is impregnated with another thermoplastic type impregnation material and the blade body comprises a trailing edge element comprising another thermoplastic type construction material and which is attached to the trailing edge by overmolding.

The invention also relates to a turbomachine comprising a blade as described above as well as a method of manufacturing a turbine blade comprising the following steps:

- a step of prefabricating a fiber preform of a blade body comprising a leading edge and a trailing edge;

- a step of impregnating at least part of one of the two edges using a first thermoplastic type impregnation material;

- a resin injection step;

- a step of injecting a thermoplastic material to form a protective element on the part by overmolding.

Advantageously, the impregnation step includes the following steps:

- a step of positioning a film in the first thermoplastic material on the edge;

- a step of applying impregnation pressure to the thermoplastic film;

- and/or a heating step at an impregnation temperature of the thermoplastic film.

Preferably, the impregnation step comprises a step of monitoring the impregnation pressure and/or the impregnation temperature as well as a step of stopping the impregnation when the impregnation pressure and/or the impregnation temperature is lower than a predefined value.

According to a particular embodiment, the resin injection step is carried out using the resin transfer molding process and/or the prefabrication, impregnation and resin injection steps take place in a single tool mold kept closed during all of these steps.

Other characteristics and advantages of the invention will appear on reading the following description of a particular non-limiting embodiment of the invention.

Reference will be made to the attached figures, including:
FIG. 1 There FIG. 1 is a schematic longitudinal sectional view of an aircraft engine;
FIG. 2 There FIG. 2 is a schematic perspective view of a turbomachine blade;
FIG. 3 There FIG. 3 is a partial schematic cross-sectional view of the first and second steps of the method according to a first embodiment of the invention;
FIG. 4 There FIG. 4 is a partial schematic cross-sectional view of a fourth step of the method according to the first embodiment of the invention;
FIG. 5 There FIG. 5 is a partial schematic cross-sectional view of a fifth step of the method according to the first embodiment of the invention;
FIG. 6 There FIG. 6 is a partial schematic cross-sectional view of a sixth step of the method according to the first embodiment of the invention;
FIG. 7 There FIG. 7 is a partial schematic cross-sectional view of a seventh step of the method according to the first embodiment of the invention;
FIG. 8 There FIG. 8 is a partial schematic view of detail in side view of a blade according to the first embodiment of the invention;
FIG. 9 There FIG. 9 is a partial schematic cross-sectional view of an eighth step of the method according to the first embodiment of the invention;
FIG. 10 There FIG. 10 is a schematic perspective view of a turbomachine blade according to the first embodiment of the invention.
FIG. 11 There FIG. 11 is a partial schematic cross-sectional view of an eighth step of the method according to a second embodiment of the invention;
FIG. 12 There FIG. 12 is a schematic perspective view of a turbomachine blade according to the second embodiment of the invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

The method for manufacturing a turbine blade 12 according to the invention will be described with reference to Figures 1 to 9. According to a first prefabrication step, a fiber preform 20 of the body 11 of the blade 12 is manufactured. This preform 20 is here made of carbon fiber with 3D woven plies. In all of the figures and for the sake of clarity, the body 11 of the blade 12 has been partially represented in the form of an upstream portion of a leading edge 13 composed of fifteen strands 21.

According to a second impregnation step, a continuous film 30 made of Polyetherketone (PEK) is positioned in a first tool mold 25. The film 30 is, here, made up of two portions 31 and 32 intended to be applied respectively to a portion of the intrados 16 and a portion of the extrados 17 of the body 11 to cover the leading edge 13 over the entire height of the blade 12. According to a third step shown in FIG. 3 , the preform 20 is introduced into the mold 25 to come into contact with the film 30. The mold 25 is then closed. According to a fourth step shown in FIG. 4 , two jaws 26 and 27 of the mold 25 are activated to apply an impregnation pressure to the film 30. The jaws 26 and 27 are also heated to an impregnation temperature of, here, between three hundred and four hundred degrees centigrade. During this fourth step, a fifth step of monitoring the impregnation pressure and the impregnation temperature is implemented. When the impregnation pressure and/or the impregnation temperature becomes lower than a predefined value, the impregnation step is stopped by stopping the application of pressure and heat to the film 30 ( FIG. 5 ).

The various pressure and temperature parameters as well as the predefined values for these parameters are chosen so that the portion 13.1 of the leading edge 13 which is impregnated has a thickness e _13.1 substantially equal to the diameter of a strand 21 ( FIG. 5 )

According to a sixth resin injection step shown in FIG. 6 , a polyimide type epoxy resin 33 is injected into the mold 25 using the resin transfer molding process. The mold 25 is then opened, and the preform 20—thus injected with epoxy resin 33 and a portion of the leading edge 13 of which is impregnated with PEK—is extracted from the mold 25.

According to a seventh presentation step represented in FIG. 7 , the leading edge 13 impregnated with the film 30 is positioned in a second tooling mold 40. The second mold 40 is a thermoplastic injection overmolding mold and has a first overmolding volume 41 of a leading edge element 34

According to an eighth assembly step represented in FIG. 9 , a thermoplastic material - here Polyetheretherketone (PEEK) - is injected into the mold 40 which forms the leading edge element 34 which is then attached to the leading edge 13 of the blade 12 by overmolding.

The first overmolding volume 41 is shaped so that the leading edge 34 obtained after overmolding has serrations 35, also called serrations ( FIG. 8 ).

A blade 12 is thus obtained comprising a blade body 11 made of carbon fiber/epoxy resin composite material 33 extending in a main direction EV. The body 11 has a lower surface 16 and an upper surface 17 connected in an upstream part of the body 11 by a leading edge 13 and in a downstream part of the body 11 on the other hand by a trailing edge 14. The upstream and downstream parts are located on either side of the main direction EV and the leading edge 13 comprises a leading edge portion 13 which is at least partially impregnated with PEK. The blade 12 comprises a leading edge element 34 made of PEEK added by overmolding on the blade body 11 ( FIG. 10 ).

According to a second embodiment of the invention shown in figures 11 and 12, and in a manner homologous to the leading edge 13, the trailing edge 14 of the blade 12 is also impregnated with PEK according to a method identical to that described previously. The second tooling mold 40 comprises, according to this second embodiment, a second overmolding volume of a trailing edge element 44 which has serrations 45. A blade 12 is then obtained comprising a blade body 11 made of carbon fiber/epoxy resin composite material 33 extending in a main direction EV. The body 11 has a lower surface 16 and an upper surface 17 connected in an upstream part of the body 11 by a leading edge 13 and in a downstream part of the body 11 on the other hand by a trailing edge 14. The upstream and downstream parts are located on either side of the main direction EV and the leading edge 13 comprises a leading edge portion 13 which is at least partially impregnated with PEK. The blade 12 comprises a leading edge element 34 and a trailing edge element 44, both made of PEEK, and which are added by overmolding on the blade body 11 ( FIG. 12 ).

Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

• bien qu’ici la préforme soit constituée de fibres de carbone à plis tissés, l’invention s’applique également à d’autres types de préforme comme par exemple une préforme constituée de fibre de verre ou d’aramide, partiellement ou totalement co-tissées ou non. La préforme fibreuse peut être de type interlock, ou à plis unidirectionnels 1D ou 2D rapportés ;
• bien qu’ici le film appliqué sur le bord d’attaque soit en Polyetherketone, l’invention s’applique également à d’autres types de premier matériau thermoplastique comme par exemple le Polyétherétherketone ou le Polyétherimide ;
• bien qu’ici l’imprégnation se fasse à l’aide d’un film continu appliqué sur toute la hauteur de la pale, l’invention s’applique également à d’autres types d’imprégnation, par exemple à l’aide d’un film discontinu ou d’un dépôt par pulvérisation ou au pinceau, ou d’une imprégnation discontinue pouvant également ne pas s’étendre sur toute la hauteur de la pale ;
• bien qu’ici le film soit en Polyimide, l’invention s’applique également à d’autres types de résines, préférentiellement thermodurcissables, comme par exemple une résine de type Bismaléimide ;
• bien qu’ici l’élément de bord d’attaque soit en Polyetheretherketone, l’invention s’applique également à d’autres types de matériau de construction de type thermoplastique comme par exemple du Polyetherimide ou du Polyetherketone. L’élément de bord d’attaque peut ne pas être composé exclusivement du matériau thermoplastique de construction mais comprendre un mélange de matériau comprenant au moins un matériau de type thermoplastique ;
• bien qu’ici le film appliqué sur le bord de fuite soit en Polyetherketone, l’invention s’applique également à d’autres types d’autre matériau thermoplastique d’imprégnation comme par exemple le Polyétherétherketone ou le Polyétherimide ;
• bien qu’ici l’élément de bord de fuite soit en Polyetheretherketone, l’invention s’applique également à d’autres types d’autre matériau de construction de de type thermoplastique comme par exemple du Polyetherimide ou du Polyetherketone ;
• bien qu’ici la pièce soit une pale de turbine de turbomachine, l’invention s’applique également à d’autres types de pièces aéronautiques portant un élément de protection comme par exemple une pale de distributeur OGV ;
• bien qu’ici la pièce soit une pale de turbine de turbomachine, l’invention s’applique également à d’autres types de pièces aéronautiques comme par exemple les carters, les plateformes,
• bien qu’ici la pale possède un bord de fuite et un bord d’attaque portant un élément de protection rapporté par surmoulage, l’invention s’applique également à d’autres types de pales comme par exemple une pale comprenant un corps en matériau composite possédant un bord d’attaque métallique , pouvant être recouvert de matériau thermoplastique formant un élément de protection de bord d’attaque, et un bord de fuite sur lequel est rapporté un élément de protection supplémentaire ;

Especially,

• although here the preform is made of carbon fibers with woven plies, the invention also applies to other types of preform such as for example a preform made of glass fiber or aramid, partially or totally co-woven or not. The fiber preform can be of the interlock type, or with added 1D or 2D unidirectional plies;
• although here the film applied to the leading edge is made of Polyetherketone, the invention also applies to other types of first thermoplastic material such as for example Polyetheretherketone or Polyetherimide;
• although here the impregnation is carried out using a continuous film applied over the entire height of the blade, the invention also applies to other types of impregnation, for example using a discontinuous film or deposition by spraying or brushing, or discontinuous impregnation which may also not extend over the entire height of the blade;
• although here the film is made of Polyimide, the invention also applies to other types of resins, preferably thermosetting, such as for example a Bismaleimide type resin;
• although here the leading edge element is made of Polyetheretherketone, the invention also applies to other types of thermoplastic construction material such as for example Polyetherimide or Polyetherketone. The leading edge element may not be composed exclusively of the thermoplastic construction material but comprise a mixture of material comprising at least one thermoplastic material;
• although here the film applied to the trailing edge is made of Polyetherketone, the invention also applies to other types of other thermoplastic impregnation material such as for example Polyetherketone or Polyetherimide;
• although here the trailing edge element is made of Polyetheretherketone, the invention also applies to other types of other thermoplastic construction material such as for example Polyetherimide or Polyetherketone;
• although here the part is a turbomachine turbine blade, the invention also applies to other types of aeronautical parts carrying a protective element such as for example an OGV distributor blade;
• although here the part is a turbomachine turbine blade, the invention also applies to other types of aeronautical parts such as for example casings, platforms,
• although here the blade has a trailing edge and a leading edge carrying a protective element added by overmolding, the invention also applies to other types of blades such as for example a blade comprising a body made of composite material having a metallic leading edge, which can be covered with thermoplastic material forming a leading edge protective element, and a trailing edge on which an additional protective element is added;

the leading edge element may not be composed exclusively of the second thermoplastic material but comprise a mixture of material comprising at least one thermoplastic-type material.

Claims (12)

Aeronautical part (10) comprising a body (11) made of composite material which has a portion (13, 14) which is at least partially impregnated with an impregnation material (30) of thermoplastic type and a protective element (34, 44) comprising a construction material of thermoplastic type which is added by overmolding onto the portion. Aeronautical part (10) according to claim 1, in which the aeronautical part (10) comprises a turbomachine blade (12) comprising:

• a body (11) of a blade (12) made of composite material extending in a main direction (EV), the body (11) having a lower surface (16) and an upper surface (17) connected in an upstream part of the body (11) by a leading edge (13) and in a downstream part of the body (11) on the other hand by a trailing edge (14), the upstream and downstream parts being located on either side of the main direction (EV);
• the portion which is at least partially impregnated with an impregnating material (30) of thermoplastic type is a portion of an edge chosen from the leading edge (13) and the trailing edge (14);
• the protective element (34,44) is a leading edge element (34) or a trailing edge element (44).

Aeronautical part (10) according to claim 2, in which the protective element (34, 44) has serrations (35). Aeronautical part (10) according to one of the preceding claims, in which the impregnation material is chosen from the following types of materials: PolyEtherimide, Polyetheretherketone, Polyetherketone. Aeronautical part (10) according to any one of the preceding claims, in which the portion has a thickness substantially equal to the diameter of a strand (21) of a fiber of the composite material. Aeronautical part (10) according to any one of the preceding claims, in which the composite material is at least partially impregnated with a thermosetting resin. Aeronautical part (10) according to any one of the preceding claims, in which the protective element (34, 44) comprises at least one metal reinforcement. Method for manufacturing an aeronautical part (10) comprising the following steps:

• a step of prefabricating a fiber preform (20) of a body (11) of an aeronautical part (10) comprising a portion (13, 14) such as a leading edge (13) or a trailing edge (14);
• a step of impregnating at least part of the portion (13, 14) using a thermoplastic type impregnation material;
• a resin injection step (33);
• a step of injecting a thermoplastic material to form a protective element (34, 44) on the portion (13, 14) by overmolding.

A manufacturing method according to claim 8, wherein the impregnation step comprises the following steps:

• a step of positioning a film (30) of the thermoplastic impregnation material on the portion (13, 14);
• a step of applying an impregnation pressure to the film (30);
• and/or a heating step at a film impregnation temperature (30).

Manufacturing method according to claim 9, wherein the impregnation step comprises a step of monitoring the impregnation pressure and/or the impregnation temperature as well as a step of stopping the impregnation when the impregnation pressure and/or the impregnation temperature is lower than a predefined value. Manufacturing method according to any one of claims 8 to 10, wherein the resin injection step (33) is carried out according to the resin transfer molding method. Manufacturing method according to any one of claims 8 to 11, in which the steps of prefabrication, impregnation and resin injection take place in a single tool mold (25) kept closed during all these steps.