FR3100468A1 - MANUFACTURING PROCESS OF AN AIRCRAFT TURBOMACHINE PART - Google Patents

Abstract

The invention provides a method of manufacturing a part (1) of an aircraft turbomachine, the part (1) comprising a body (2) of composite material and at least one metallic element (3). The method comprises the steps of (a) manufacturing the body (2) of composite material, (b) machining the body (2), and (c) assembling the body (2) with said at least one metallic element (3) . According to the invention, the method comprises the following step (d) of applying a fire protection layer (4) to the assembly comprising the body (2) and said at least one metallic element (3). Figure for the abstract: Figure 1

Description

METHOD FOR MANUFACTURING AN AIRCRAFT TURBOMACHINE PART

Technical field of the invention

The technical field of the invention is that of methods for manufacturing an aircraft turbomachine part comprising in particular a step of applying a fire protection layer.

Technical background

Many aeronautical items of equipment have parts comprising metal hydride/composite assemblies (in particular with an organic matrix) located in particular in a fire zone of the aircraft, such as for example a turbomachine of the aircraft.

In such an area, this type of part can be subjected to flames with temperatures around 1100°C. With the rise in temperature, the composite material of the part will reach the degradation temperature of the resin forming the organic matrix. Degradation will then begin and decomposition gases will be generated and may escape both to one side of the part exposed to the flame and to one side of the part not exposed to the flame (i.e. say by crossing the entire room). Thus, depending on the geometry of the part, the assembly and the porosity induced by the coverage rate of the fibers of the part and the degradation of the organic matrix, a certain concentration of gas will escape, including combustible gases that can either interact with the flame and fuel it, or diffuse into the environment of the room.

In order to be able to validate the various regulatory fire resistance requirements, it is necessary to limit these phenomena of degradation and gas release. It is known for this to apply a layer of fire protection such as paints or fabrics containing flame retardants. These fire protection layers are applied after machining of the composite material part and before assembly of the metal elements, i.e. only on an external surface of the composite material part presenting the main fire risk, without take into account the remote environment of the part in its final installation.

However, these fire protection layers do not completely prevent the phenomena of degradation and gas release. In addition, due to the convection of air from the "hot" fire zone to the "cold" zones farther from the fire zone and the good thermal conductivity properties of metals, the metal elements not protected by the protective layer at the fire will heat up. These metallic elements present around the zone exposed to the fire can thus reach a temperature which is higher than the ignition temperatures of the gases released by the composite material with an organic matrix in the environment of the part and an ignition of the combustible gases can then occur. A spread or resumption of fire is therefore possible, which is not authorized by the aeronautical regulatory requirements (AC20-135 of the FAA and CS-E 130 of the EASA).

Thus, the presence around the fire event of metallic elements with thermal properties and reactivities very different from those of composite materials, can give rise to greater degradation of the assemblies, the aggravating synergies of which are moreover difficult. to anticipate, even when the metal elements are not in contact with the composite elements directly subjected to the fire.

The object of the present invention is in particular to solve all or part of the aforementioned problems.

The invention proposes for this purpose a method of manufacturing an aircraft turbomachine part in which the part comprises a body made of composite material and at least one metallic element. The method comprises the steps of (a) fabricating the body of composite material, (b) machining the body, and (c) assembling the body with said at least one metallic element.

According to the invention, the method comprises a following step (d) of applying a fire protection layer to the assembly comprising the body and said at least one metallic element.

The invention proposes applying fire protection to the entire part, i.e. when the metal element(s) are already assembled with the composite material body. The invention thus provides protection from fire also for the metal element(s) of the part, including when they are not located in an area of the part directly subject to a fire risk. The invention therefore makes it possible to reduce the temperature rise of the metal elements of the part so as to reduce the risks of ignition of the combustible degradation gases released by the composite body during a fire and to satisfy the aforementioned regulatory requirements.

This technical solution represents an inversion of the order of the finishing steps in the usual industrial plan for the preparation of parts and assemblies which limits the application of the fire protection layer to the part of the part mainly subjected to fire, c ie the body made of composite material.

The process may include one or more of the following features and/or steps, taken alone with each other or in combination with each other:

• the protective layer is applied to the assembly by spraying;
• the protective layer is applied with a constant or non-constant thickness (variable thickness);
• the protective layer is an intumescent paint layer;
• the protective layer comprises the paint marketed by the Rescoll® company under the reference 0617;
• body is made of organic matrix composite;
• the body is made of epoxy matrix composite;
• at least one metal element is aluminum or titanium;
• between steps c) and d), the method includes a step of preparing the assembly by sandblasting, with or without application of primer; And
• the assembly comprises two zones including a main zone likely to be directly exposed to a fire, and a secondary zone, the fire protection layer being applied in step d) on the secondary zone only.

Brief description of figures

The invention will be better understood and other details, characteristics and advantages of the invention will appear more clearly on reading the following description given by way of non-limiting example and with reference to the attached drawing in which:

FIG. 1 is a schematic view of a method for manufacturing an aircraft turbomachine part according to the invention.

Detailed description of the invention

As illustrated in FIG. 1, the invention relates to a method for manufacturing a part 1 of an aircraft turbomachine, comprising a body 2 made of composite material and at least one metallic element 3. The body 2 is for example made of composite with an organic matrix and is in particular a composite with an epoxy matrix. The metallic element 3 is for example made of aluminum or titanium.

The process includes the steps of:

a) manufacture of the body 2 in composite material;

b) machining of body 2; And

c) assembly of the body 2 with said at least one metal element 3. The element 3 is for example mounted in a machined housing of the body.

According to the invention, the method further comprises a following step d) of applying a fire protection layer 4 to the assembly comprising the body 2 and said at least one metal element 3. It is understood here that the application of the fire protection layer 4 is carried out after the assembly of the body 2 with said at least one metallic element 3.

The protective layer 4 is for example applied to the assembly by spraying. This is, for example, a sprayable protection of the paint, mastic and/or foam type which can be used for their good thermal barrier properties and their ease of application.

The protective layer 4 is in particular applied with a thickness, preferably constant but which may not be as a variant. This makes it possible to avoid different deposited thicknesses of the fire protection layer and therefore to avoid variable levels of baking of the layer. A variable level of cooking is indeed to be avoided, in particular because it can lead to an altered resistance to external aggressions (for example to temperatures, fluids, humidity). The thickness deposited is therefore a critical point of the process and must be controlled during spraying, in particular by taking into account the angle of deposition, the geometry of the part, the way in which the operation is carried out (manual or robotic) , the distance between the means of application of the fire protection layer and the part, the flow rate and the speed of movement of the application.

Another difficulty comes from the fact that a spray application on parts of various nature and shape is not obvious. Indeed, by spraying the fire protection directly on the complete assembly comprising the composite body and the metal element(s), the fire protection layer must be applied correctly and with good adhesion to the different materials. One embodiment of the invention provides for this the use of a layer of intumescent paint and in particular a paint marketed by the company Rescoll® under the reference 0617, as fire protection layer 4. The intumescent paint is in fact, a paint that is particularly well suited, particularly in terms of adhesion, to direct application aimed at a part comprising a body made of composite material and at least one metallic element. It is a paint providing protection against fire by swelling under the effect of temperature.

In addition, the intumescent paint can be applied directly without primer on woven and laminated composite materials based on epoxy resin and on aluminum and titanium materials, sandblasted according to the usual recommendations. The method thus advantageously comprises a step of preparing the assembly by sandblasting, preferably without applying primer before applying the fire protection layer. However, the use of a primer is possible.

The invention can therefore be implemented by carrying out only a simple surface preparation of the part 1, such as sandblasting without applying a primer.

The assembly comprises for example two zones, including a main zone likely to be directly exposed to a fire, and a secondary zone, the fire protection layer 4 being applied in step d) on the secondary zone only. Sprayed applications of fire protection layer 4 can thus be carried out on the metal elements present in the environment close to the fire risk zone but not in direct contact with this zone, with the aim of reducing as much as possible the elevation in temperatures of the metallic elements and therefore reduce the risks associated with the ignition of the combustible gases released during the degradation of the organic matrix of the composite.

Claims (10)

Method for manufacturing an aircraft turbomachine part (1), this part (1) comprising a body (2) made of composite material and at least one metallic element (3), the method comprising the steps of:
a) manufacture of the body (2) in composite material,
b) machining of the body (2),
c) assembly of the body (2) with said at least one metallic element (3),
characterized in that it comprises a following step d) of applying a fire protection layer (4) to the assembly comprising the body (2) and the said at least one metallic element (3). Method according to Claim 1, in which the protective layer (4) is applied to the assembly by spraying. Method according to Claim 1 or 2, in which the protective layer (4) is applied with a constant thickness. Method according to one of the preceding claims, in which the protective layer (4) is an intumescent paint layer. Method according to claim 4, in which the protective layer (4) comprises the paint marketed by the company Rescoll® under the reference 0617. Method according to one of the preceding claims, in which the body (2) is made of a composite with an organic matrix. Method according to Claim 6, in which the body (2) is made of an epoxy matrix composite. Method according to one of the preceding claims, in which the said at least one element (3) is made of aluminum or titanium. Method according to one of the preceding claims, in which it comprises, between steps c) and d), a step of preparing the assembly by sandblasting, with or without application of primer. Method according to one of the preceding claims, in which the assembly comprises two zones including a main zone likely to be exposed directly to a fire, and a secondary zone, the fire protection layer (4) being applied to the step d) on the secondary zone only.