FR3136010A1 - METHOD FOR MANUFACTURING AN ANNULAR TURBOMACHINE HOUSING - Google Patents

Abstract

The invention relates to a method of manufacturing an annular turbomachine casing, comprising: - at least one step (ET1) of producing an annular body, - at least one step (ET2) of producing at least one member suspension of the turbomachine projecting from an external surface of said body, characterized in that the step (ET1) of producing the body is carried out by rolling and turning and in that the step (ET2) of producing said at least a suspension member is carried out after the step (ET1) of producing said body and comprises at least one sub-step (SET2) of fixing to said body at least one added element carrying said at least one suspension member by welding . Figure for abstract: Figure 11.

Description

METHOD FOR MANUFACTURING AN ANNULAR TURBOMACHINE HOUSING Technical field of the invention

The invention relates to a method of manufacturing an annular turbomachine casing, in particular an annular casing forming an outer shell of an intermediate turbomachine casing, this annular casing comprising a suspension member intended to allow the attachment of the turbomachine to a pylon of an aircraft equipped with this turbomachine.

Technical background

A turbojet engine for propelling an aircraft generally includes an upstream fan delivering an annular air flow. The fan is contained in a fan housing. Downstream of the fan is an intermediate casing comprising an internal hub and an annular casing or external annular shroud joined by structural arms and outlet guide vanes, known by the acronym "outlet guide vanes" or OGV .

The annular air flow is divided, downstream of the fan, by the annular intermediate hub into a primary flow, which powers a motor driving the fan, and into a secondary flow which circulates around the motor then which is ejected into the atmosphere while providing a significant fraction of the turbojet thrust.

The annular casing conventionally comprises in its upper part also called "12h zone" with reference to the position of the hands on the dial of a clock, an interface for fixing to a pylon of the aircraft, comprising for example lugs or yokes fixing to the pylon.

The annular casing, conventionally, is produced by assembling by welding angular sectors of the casing from the foundry. These angular sectors are machined on their edges to allow as precise a fit as possible of the sectors to each other and some of these have fixing lugs and clevises, which have functional surfaces which must also be machined in order to receive complementary fixing members of the pylon.

This design is generally satisfactory but has various drawbacks.

Foundry parts are heavy, due to the need to have sufficient structural rigidity and to have sufficient excess thickness for subsequent machining.

Foundry parts represent a high cost and their machining by milling also entails high costs.

Finally, the foundry, milling, adjustment and welding stages of the different sectors, due to their cumulative duration, generate significant industrialization times.

There is therefore a real need for simplified manufacturing of the annular casing of this casing, making it possible to reduce costs and production times.

The invention achieves this goal by proposing a new design of a casing produced by rolling and turning on which the fixing members are attached by a welding or soldering process.

For this purpose, the invention proposes a method of manufacturing an annular turbomachine casing, comprising:

- at least one step of producing an annular body,

- at least one step of producing at least one suspension member of the turbomachine projecting on the external surface of said body,

characterized in that the step of producing the body is carried out by rolling and turning and in that the step of producing said at least one suspension member is carried out subsequent to the step of producing said body and comprises at least one sub -step of fixing to said body at least one added element carrying said at least one welding suspension member.

Compared to the processes known in the art, the replacement of the operations of molding, machining and assembly of the sectors of the body by the rolling and turning of a single-piece body allows both a significant saving of material, and a considerable time saving because it is no longer necessary to adjust or weld individual sectors. In addition, the manufacturing of the casing is simplified because the suspension member is no longer initially part of the casing, the machining of its functional surfaces can be carried out in hidden time independently of the manufacturing of the annular body.

According to other characteristics of the process:

- the step of producing said at least one suspension member comprises a sub-step of machining the body, prior to the fixing sub-step, during which at least one through opening is produced in the radial direction relative to a main axis of the body, and, during the fixing sub-step, said at least one attached element is welded or brazed, with dimensions complementary to those of said at least one opening, in said at least one opening,

- said at least one added element comprises a plate of dimensions complementary to those of the at least one opening, which is welded in said at least one opening during the fixing sub-step, and said at least one suspension member comprises at least one tab which projects from said plate substantially in a radial direction relative to a main axis of the casing and which extends in a plane oriented perpendicular to the axis of the casing,

- said at least one suspension member comprises two pairs of two parallel legs defining two yokes arranged symmetrically on either side of a central leg,

- the method comprises an additional step of milling at least one surface of the legs intended to cooperate with a complementary member of an aircraft pylon,

- the plate has a curvature, in a plane perpendicular to an axis of the casing, which is equal to that of the body of the casing,

- in the plane perpendicular to the axis of the casing, a thickness of the plate in its middle is greater than a thickness of the longitudinal edges of the plate,

- during the stage of producing the annular body, annular elements projecting from the external surface of the body are formed by rolling, then said annular elements are machined on a lathe,

- the annular elements are fixing flanges and/or stiffeners of said casing.

The invention also relates to a dual-flow turbomachine comprising a fan and, downstream of said fan, a casing of the type described above.

Brief description of the figures

Other characteristics and advantages of the invention will appear during reading of the detailed description which follows, for the understanding of which we will refer to the appended drawings in which:

there is a sectional view of a turbojet engine;

there is an exploded perspective view of an annular casing according to the state of the art;

there is a perspective view of an intermediate casing comprising an annular casing according to the invention;

there is a half-view in axial section of a body of an annular casing according to the invention;

there is a perspective view of the body of the annular casing according to the invention;

there is a perspective view of the annular casing according to the invention;

there is a perspective view of the suspension members of the annular casing according to the invention;

there is a half-view in axial section of the annular casing according to the invention;

there is a detailed cross-sectional view of the annular casing according to the invention;

there is a block diagram illustrating the steps of a manufacturing process according to the state of the art; And

there is a block diagram illustrating the steps of a manufacturing process according to the invention.

Detailed description of the invention

We represented at the a turbomachine 10 with double flow of axis here an intermediate casing 14 which subdivides the flow F into a primary flow P and a secondary air flow S.

The primary flow circulates in a primary vein 16 and successively passes through a low pressure compressor 18, a high pressure compressor 20, a combustion chamber 22 where the air is mixed with fuel then ignited to provide high energy gases, a turbine high pressure 24, a low pressure turbine 26, and a nozzle 28.

The secondary flow S circulates around a core 30 of the turbojet in a secondary stream 32.

The intermediate casing 14 comprises a hub 32 and an annular casing or shroud 34 which are connected by outlet guide vanes, also known by the acronym OGV for "outlet guide vanes" and by structural arms 36, who alone were represented on the .

Such an external annular casing 34 is obtained by a process comprising at least one step of producing an annular body 44 and at least one step of producing at least one member 46 for suspending the turbomachine projecting on an external surface 48 of said body 44.

Conventionally, these two stages are concomitant and are the subject of a foundry operation.

Indeed, as illustrated by , an external annular casing 34 or ferrule is produced in the form of an assembly of angular casing sectors 40 which come from the foundry and which are assembled by welding their edges 42 parallel to the axial direction X.

As can be seen on the , the meeting of the angular sectors determines the annular body 44 of the casing 34. A sector 40a of the sectors 40, which is arranged in the upper position of the main body 44 in a position called "at 12 o'clock" with reference to the position of the hands of a clock at 12 o'clock, comprises at least one suspension member 46 of the turbomachine, also from a foundry, which projects from an external surface 48 of the body 44.

We will therefore understand that, as illustrated by , the casing 34 is produced during at least one step ET1 of producing an annular body 44 by casting sectors 40 which is concomitant with at least one step ET2 of producing by casting the at least one suspension member 46.

In particular, the at least one suspension member 46 comprises two pairs of two parallel legs 46a defining two yokes 46b arranged symmetrically on either side of a central leg 46c. The yokes 46b and the central tab 46c allow, in a known manner, the suspension of the turbomachine via the intermediate casing 14 and its annular casing 34, to a pylon of the aircraft, directly or via a latticework of connecting rods.

This design is generally satisfactory but has various drawbacks.

The angular sectors 40 from foundry are heavy parts, due to the need to have sufficient structural rigidity and to have sufficient excess thickness for subsequent machining. Indeed, the assembly of the edges 42 by welding requires a minimum thickness thereof. In addition, these parts, since they come from a foundry, represent a high industrialization cost and their machining by milling also entails high costs.

Finally, the stages of foundry, milling, adjustment and welding of the different angular sectors 40, due to their cumulative durations, generate significant industrialization times.

There is therefore a real need for a simplified design of the annular casing 34, making it possible to reduce costs and production times.

The invention remedies these drawbacks by proposing a method of manufacturing an annular casing 34 of a turbomachine, comprising, as previously and as illustrated by , at least one step ET1 of producing the annular body 44, and at least one step ET2 of producing the at least one member 46 for suspending the turbomachine projecting on the external surface 48 of said body 44.*

However, unlike the process from the state of the art, step ET1 of producing the body 44 is carried out by rolling and turning and step ET2 of producing said at least one suspension member 46 is not carried out concomitantly with step ET1 but is carried out after step ET1. In addition, step ET2 comprises at least one sub-step SET2 of fixing to said body 44 of at least one carrying insert 50 of the at least one suspension member 46 by welding.

There illustrates the profile in axial section of the body 44 of the annular casing 34 obtained at the end of the rolling and turning step. This technology being widely known from the state of the art, it will not be further described in the present invention. It allows the forming by rolling of annular elements 45 projecting from the external surface 48 of the body 44, then the lathe machining of these annular elements 45. These annular elements 45, also visible at the , are fixing flanges and/or stiffeners of the casing 34.

A casing 34 obtained according to this process has been shown in Figures 3, 6 and 7. As can be seen in these figures, and more precisely in , the added element 50 comprises a plate 52 and, as previously described with reference to the state of the art, said at least one suspension member 46 comprises at least one tab 46a which projects from said plate 52 substantially according to a radial direction R relative to a main axis X of the casing and which extends in a plane P oriented perpendicular to the axis X of the casing.

Preferably, in the annular casing 34 according to the invention, the at least one suspension member 46 comprises as before two pairs of two parallel legs 46a defining two yokes 46b arranged symmetrically on either side of a central leg 46c .

The plate 52 could be fixed directly on the external surface 48 of the body 44. However, preferably the plate 52 is arranged in continuity with the external surface 48 of the body 44.

For this purpose, the step ET2 of producing the at least one suspension member comprises a sub-step SET1 of machining the body, prior to the fixing sub-step SET2, during which at least one opening is produced. through 54 in the radial direction R with respect to the main axis the fixing sub-step SET2 welds or brazes said at least one added element 50 by welding or brazing its plate 52 in said at least one opening 54.

There illustrates the body 34 in which the through opening 54 has been produced by machining, and the represents the added element 50 in position, its plate 52 being welded in the opening 54.

As can be seen on the , its transverse edges 54 of the plate 52, oriented parallel to the plane P, are welded edge to edge with edges 56 of the opening 54. As can be seen in the , longitudinal edges 58 of the plate 52, oriented parallel to the axis X, are welded edge to edge with edges 60 of the opening 54.

In this way the plate 52 does not form any extra thickness compared to the body 44.

As illustrated by , the plate 52 has a curvature, in the plane P perpendicular to the axis , a thickness e1 of the plate 52 in its middle, is greater than the thickness e2 of its longitudinal edges 58. The thickness of the plate 52 decreases as it approaches the longitudinal edges 58 with a determined slope.

Advantageously, the plate can also play a role of structural reinforcement. It may in particular include holes 62 allowing the passage of fixing screws of the upper structural arm 36, called the “12 o’clock” arm.

Finally, advantageously, the manufacturing process comprises an additional step ET3 of milling functional surfaces of the at least one suspension member 46, that is to say the lugs 46a, 46c. More particularly during this step, at least one surface of each tab 46a, 46c is milled, capable of cooperating with a complementary member of the pylon or the connecting rod lattice of the aircraft.

The invention therefore makes it possible to simplify the manufacture of an external annular casing 34 of an intermediate casing 14 of a turbomachine.

Claims (10)

Method of manufacturing an annular casing (34) of a turbomachine (10), comprising at least:
- a step (ET1) of producing an annular body (44),
- at least one step (ET2) of producing at least one member (46) for suspending the turbomachine projecting from an external surface (48) of said body (44),
characterized in that the step (ET1) of producing the body (44) is carried out by rolling and turning, and in that the step (ET2) of producing said at least one suspension member (46) is carried out after the step (ET1) of producing said body (44) and comprises at least one sub-step of fixing (SET2) to said body of at least one attached element (50) carrying said at least one suspension member (46) by welding. Manufacturing method according to the preceding claim, characterized in that the step (ET2) of producing said at least one suspension member comprises a sub-step (SET1) of machining the body (44), prior to the sub-step of fixing (SET2), during which at least one through opening (54) is produced in the radial direction (R) relative to a main axis (X) of the body, and in that, during the sub-step ( SET2) for fixing, said at least one added element (50), of dimensions complementary to those of said at least one opening (54), is welded or brazed, in said at least one opening (54), Manufacturing method according to the preceding claim, characterized in that said at least one added element (50) comprises a plate (52) of dimensions complementary to those of the at least one opening (54), which is welded in said at least an opening (54) during the fixing sub-step (SET2), and in that said at least one suspension member (46) comprises at least one tab (46a, 46c) which projects from said plate (52) substantially in a radial direction (R) relative to a main axis (X) of the casing (34) and which extends in a plane (P) oriented perpendicular to the axis (X) of the casing (34) . Manufacturing method according to the preceding claim, characterized in that said at least one suspension member (46) comprises two pairs of two parallel legs (46a) defining two yokes (46b) arranged symmetrically on either side of a leg central (46c). Manufacturing method according to the preceding claim, characterized in that it comprises an additional step (ET3) of milling at least one surface of each tab (46a, 46c), said surface being intended to cooperate with a complementary member of an aircraft pylon. Manufacturing method according to one of claims 3 to 5, characterized in that the plate (52) has a curvature, in a plane (P) perpendicular to an axis (X) of the casing (34), which is equal to that of the body (44) of the casing, Manufacturing method according to the preceding claim, 3 to 5, in that, in the plane (P) perpendicular to the axis (X) of the casing (34), a thickness (e1) of the plate in its middle is greater than a thickness (e2) of longitudinal edges (58) of the plate (60). Method according to one of the preceding claims, characterized in that, during step (ET1) of producing the annular body (44), annular elements (45) projecting from the external surface (48) are formed by rolling. ) of the body, then said annular elements (45) are machined on a lathe. Method according to the preceding claim, characterized in that the annular elements (45) are fixing flanges and/or stiffeners of said casing (34). Dual-flow turbomachine (10) comprising a fan (12) and, downstream of said fan (12), an annular casing (34) obtained by a method according to one of the preceding claims.