METHOD FOR MANUFACTURING AN ANNULAR TURBOMACHINE CRANKCASE WITH BOSSINGS

Abstract

The invention relates to a method for manufacturing an annular turbomachine housing, comprising: - at least one step (ET1) of producing an annular body, - at least one step (ET2) of producing at least one protruding boss on the machined external surface of the body, characterized in that step (ET1) of producing the body is carried out by rolling and turning and in that step (ET2) of producing the at least one boss is carried out by additive manufacturing, subsequent to the step of producing said body. Figure for the abstract: Figure 6

Description

Description Title of the invention: METHOD FOR MANUFACTURING A TURBOMACHINE RING COVER WITH BOSSAGES Technical field of the invention

[0001] = The invention relates to a method for (manufacturing an annular casing of a tur- bomachine, in particular an annular casing forming an outer ferrule of a casing intermediate turbomachine, this annular housing having at least one boss suitable for receiving an interface for a turbomachine component. Technical background

[0002] = A turbofan engine for aircraft propulsion comprises gen- Approximately an upstream blower delivering an annular airflow. The blower is contained within a blower housing. Downstream of the blower is an intermediate housing. median comprising an internal hub and an annular casing or annular ferrule external arms joined by structural arms and guide vanes, known as the Anglo-Saxon acronym for "outlet guide vanes" or OGV.

[0003] — The annular airflow is divided, downstream of the blower, by the intermediate hub annular in a primary flow, which powers a motor driving the blower, and in a secondary flow that circulates around the engine and is then ejected into the atmosphere by providing a significant fraction of the turbojet's thrust.

[0004] The annular casing conventionally comprises, on its external surface bosses configured to form interfaces for attaching equipment or crankcase suspension brackets.

[0005] = The annular housing is conventionally produced by a welded assembly angular sectors of the crankcase, produced by casting. These angular sectors are machined on their edges to allow for the most precise possible adjustment of the sectors to each other and some of these have bosses created during the molding process, which must also be machined to form surfaces and openings allowing the fixing of equipment or suspension supports for the crankcase.

[0006] — This design is generally satisfactory but presents several incons- Venients.

[0007] Cast parts are heavy, due to the need to present a Sufficient structural rigidity and sufficient extra thickness for the subsequent machining.

[0008] Cast parts represent a high cost and their machining by milling also results in high costs. Finally, the casting, milling, fitting and welding stages of the different sectors, due to their cumulative durations, generate significant industrialization delays. There is therefore a real need for a simplified manufacturing of the annular housing of this housing, making it possible to reduce costs and production times. Summary of the invention The invention achieves this goal by proposing a new design of a casing made by rolling and turning on which the bosses are added by an additive manufacturing process. To this end, the invention proposes a method for manufacturing an annular turbomachine housing, comprising: - at least one step in the production of an annular body, - at least one step in creating at least one protruding boss on a machined external surface of the body, characterized in that the body production stage is carried out by rolling and turning and in that the production stage of said at least one boss is carried out by additive manufacturing, subsequent to the body production stage. According to other characteristics of the process: - the additive manufacturing is of the Laser Metal Deposition (LMD) type; -the process includes a subsequent machining and finishing step of said at least one boss; - the machining and finishing stage of said at least one boss includes at least the creation on said boss of a surface substantially perpendicular to a radial direction with respect to a principal axis of the housing, and the creation of at least one hole in said surface, oriented along said radial direction, - said at least one boss is configured to form an interface for attaching equipment or a suspension support to said housing, - said surface and said drilling are configured to cooperate with said equipment or said suspension support of said housing for their attachment - during the manufacturing stage of the annular body, annular elements projecting from the external annular surface of the body are formed by rolling, then these annular elements are machined on a lathe, and - the annular elements are fixing flanges and / or stiffeners of said casing. The invention also relates to a double-flow turbomachine comprising a blower and downstream of said blower an intermediate casing obtained by a process of the type described above. Brief description of the figures Other features and advantages of the invention will become apparent during the course of the Read the detailed description that follows, for an understanding of which refer to the attached drawings in which: [Fig.1] [Fig.1] is a cross-sectional view of a turbojet engine; [Fig.2] [Fig.2] is an exploded perspective view of an annular housing according to the prior art; [Fig.3] [Fig.3] is a half axial cross-sectional view of a body of an annular housing according to the invention; [Fig.4] [Fig.4] is a detailed perspective view of a boss made on an annular housing according to the invention; [Fig.5] [Fig.5] is a perspective view of the annular housing according to the invention; [Fig. 6] [Fig. 6] is a block diagram illustrating the steps of a manufacturing process according to the prior art; and [Fig.7] [Fig.7] is a block diagram illustrating the steps of a manufacturing process according to the invention. Detailed description of the invention Figure 1 shows a turbomachine 10 with a double-flow X-axis or turbojet 10. As is known, the turbojet 10 comprises, from upstream to downstream, a fan 12 surrounded by a casing 11 which draws in a main airflow F and downstream of this an intermediate casing 14 which subdivides the flow F into a primary flow P and a secondary airflow S. The primary flow circulates in a primary channel 16 and passes successively through a low-pressure compressor 18, a high-pressure compressor 20, a combustion chamber 22 where air is mixed with fuel and then ignited to provide high-energy gases, a high-pressure turbine 24, a low-pressure turbine 26, and a nozzle 28. The secondary flow S circulates around a nucleus 30 of the turbojet in a secondary channel 32. The intermediate casing 14 comprises a hub 32 and an annular casing or ferrule 34 which are connected by outlet guide vanes, also known by the Anglo-Saxon acronym OGV for "outlet guide vanes" (not shown in [Fig.1]) and by structural arms 36, Such an external annular housing 34 is obtained by a process comprising at least one step of making an annular body 44 and at least one step of making at least one boss 46 of the turbomachine projecting on an external surface 48 of said body 44. Conventionally, these two steps are concurrent and are the subject of a foundry operation. Indeed, as illustrated in [Fig.2], an external annular housing 34 or ferrule is made in the form of an assembly of angular sectors 40 of the housing which are cast and which are assembled by welding their edges 42 parallel to the axial direction X. As can be seen in [Fig.2], the union of the angular sectors determines the annular body 44 of the housing 34. At least one sector 40a, among the sectors 40, includes for example at least one boss 46 of the turbomachine, also cast, which protrudes on the external surface 48 of the body 44. Such a boss 46 is intended, after machining, to form an interface for fixing equipment or a suspension support for the crankcase. It will therefore be understood that, as illustrated in [Fig.6], the housing 34 is produced during at least one ET1 stage of production of an annular body 44 by casting of the sectors 40 which is concomitant with at least one ET2 stage of production by casting of at least one boss 46. This design is generally satisfactory but has several drawbacks. The angular sectors 40 and 40a, produced by casting, are heavy parts due to the need for sufficient structural rigidity and adequate material allowances for subsequent machining. Indeed, welding the edges 42 together requires a minimum thickness for these edges. Furthermore, these cast parts represent a high industrialization cost, and their machining by milling also entails significant costs. Finally, the casting, milling, fitting and welding stages of the various angular sectors 40, due to their cumulative durations, generate significant industrialization delays. There is therefore a real need for a simplified design of the annular housing 34, allowing for a reduction in costs and production times. The invention remedies these drawbacks by proposing a method for manufacturing an annular housing 34 of a turbomachine, comprising, as before and as illustrated in [Fig.7], at least one step ET1 of making the annular body 44, and at least one step ET2 of making at least one boss 46 of the turbomachine projecting on the external surface 48 of said body 44. However, unlike the process from the prior art, the ET1 step of producing the body 44 is carried out by rolling and turning and the ET2 step of producing said at least one boss 46 is not carried out concurrently with the ET1 step but is carried out after the ET1 step. Advantageously, during this ET2 step, the realization of at least one The bossing is done by additive manufacturing. Figure 3 illustrates the axial cross-sectional profile of the body 44 of the annular housing 34 obtained after the rolling and turning step. As this technology is widely known in the prior art, it will not be described further in the present invention. It allows for the forming by rolling of annular elements 45 projecting from the external surface 48 of the body 44, followed by the machining of these annular elements 45 on a lathe. These annular elements 45, also visible in Figure 5, are fixing flanges and / or stiffeners of the housing 34. A detail of a housing 34 obtained according to this process has been shown in [Fig.4]. In this figure, a boss 46, as added after additive manufacturing, is shown attached to the external surface 48 of the body 44. Preferably, the additive manufacturing carried out here is of the Laser Metal Deposition (LMD) type. According to this technology, a metal powder is projected and melted by a laser beam at the outlet of a high-pressure nozzle of a cladding head, in successive layers, to constitute each boss 46. In order that each boss can be used for the purpose of an interface for fixing equipment or a suspension support of said housing, as illustrated in [Fig.7], the method according to the invention advantageously includes a subsequent step ET3 of machining and finishing the boss 46. During this step ET3, as illustrated in [Fig.5], at least one surface 50 is made on the boss 46 substantially perpendicular to a radial direction R with respect to a principal axis X of the housing 34, and at least one orifice 52 is made in this surface 50, oriented along the radial direction R. The machined boss 46 provides a mounting interface for equipment or a suspension bracket for the housing, such as a pressure or speed sensor, or a suspension bracket for the housing 34 attached to a lattice of connecting rods linked to a pylon supporting the turbomachine. The equipment or suspension bracket can thus bear against the surface 50 and be locked against it by means of a locking system cooperating with the port 52, such as a screw-nut system or a flange. The invention therefore makes it possible to obtain an annular housing 34 equipped with bosses 46 at a reduced cost.

Claims

Demands

1. Method for manufacturing an annular housing (14) for a turbomachine, including: - at least one step (ET1) in the realization of an annular body (34), - at least one step (ET2) of creating at least one boss (46) in projection on a machined external surface of the body (44), characterized in that the body realization step (44) is carried out by rolling and turning and in that the step (ET2) of realization of the less one boss (46) is produced by additive manufacturing, post- later to the stage of realization of said body (44).

2. A manufacturing process according to the preceding claim, characterized in Additive manufacturing is of the Laser Metal Deposition (LMD) type.

3. A method according to any one of the preceding claims, characterized in that that it includes a subsequent machining and finishing step (ET3) of said at least one boss (46).

4. A manufacturing process according to the preceding claim, characterized in that the machining and finishing step (ET3) of said at least one boss (46) includes at least the creation on said boss of a surface (50) substantially perpendicular to a radial direction (R) with respect to to a main axis (X) of the housing, (34) and the realization of at least one orifice (52) in the surface (50), oriented along said radial direction (R).

5. A manufacturing method according to any one of the preceding claims, ca- characterized in that said at least one boss (46) is configured for to form an interface for attaching equipment or a support suspension of said crankcase (34).

6. Manufacturing method according to the preceding claim taken in com- combination with claim 4, characterized in that said surface (50) and said drilling (54) are configured to cooperate with said one equipment or said suspension support of said casing (34) for their fastening.

7. A method according to any one of the preceding claims, characterized in that that during step (ET1) of the production of the annular body, one forms by rolling the annular elements (45) protruding from the surface outer annular (48) of the body (34), then the said are machined on a lathe (45) annular elements.

8. A method according to the preceding claim, characterized in that the annular elements (45) are fixing flanges and / or stiffeners said crankcase. [Claim: Double-flow turbomachine (10) comprising a blower (12) and in downstream of said blower an intermediate casing (34) obtained by a method according to any one of claims 6 to 8.