METHOD FOR MANUFACTURING AN ANNULAR TURBOMACHINE CRANKCASE

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 turbomachine suspension element projecting from an external surface of said body, characterized in that step (ET1) of producing the body is carried out by rolling and turning, and in that step (ET2) of producing said at least one suspension element is carried out after step (ET1) of producing said body and comprises at least one substep (SET2) of attaching said body to at least one attached element carrying said at least one suspension element by welding. Figure 11 for the abstract.

Description

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

[0001] The invention relates to a method for manufacturing an annular housing for a turbomachine, in particular an annular housing forming an outer shell of an intermediate housing for a turbomachine, this annular housing comprising a suspension element intended to allow the attachment of the turbomachine to a pylon of an aircraft equipped with this turbomachine. Technical background

[0002] A turbofan engine for aircraft propulsion generally comprises an upstream fan delivering an annular airflow. The fan is contained within a fan casing. Downstream of the fan is an intermediate casing comprising an inner hub and an outer annular casing or annular ferrule joined by structural arms and outlet guide vanes, known by the English acronym "outlet guide vanes" or OGV.

[0003] The annular airflow 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 and is then ejected into the atmosphere while providing a significant fraction of the turbojet thrust.

[0004] The annular housing conventionally includes in its upper part, also called the "12 o'clock zone" by reference to the position of the hands on the dial of a clock, an interface for fixing to a pylon of the aircraft, including for example tabs or clevises for fixing to the pylon.

[0005] The annular housing is conventionally produced by welding together angular sectors of cast housing. These angular sectors are machined on their edges to allow for the most precise possible fit between the sectors, and some of them have tabs and mounting brackets, which have functional surfaces that must also be machined to receive additional pylon mounting elements.

[0006] This design is generally satisfactory but has several drawbacks.

[0007] Cast parts are heavy, due to the need to have sufficient structural rigidity and sufficient excess thickness for subsequent machining.

[0008] Cast parts represent a high cost and their machining by milling also results in high costs.

[0009] Finally, the casting, milling, fitting and welding stages of the different sectors, due to their cumulative durations, generate significant industrialization delays.

[0010] 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

[0011] The invention achieves this goal by proposing a new design of a casing made by rolling and turning on which the fixing elements are attached by a welding or brazing process.

[0012] To this end, the invention proposes a method for manufacturing an annular turbomachine housing, comprising:

[0013] - at least one step in the realization of an annular body,

[0014] - at least one step in the realization of at least one suspension element of the tower bomachine projecting from the external surface of said body,

[0015] characterized in that the body fabrication step is carried out by rolling and turning and in that the fabrication step of said at least one suspension member is carried out after the body fabrication step and includes at least one sub-step of fixing said body of at least one added element carrying said at least one suspension member by welding.

[0016] Compared to known methods of the art, replacing the molding, machining, and assembly operations of the body sectors with rolling and turning a single-piece body allows for both a significant material saving and a considerable time saving because it is no longer necessary to adjust or weld individual sectors. Furthermore, the manufacture of the housing is simplified because, since the suspension element is no longer initially part of the housing, the machining of its functional surfaces can be carried out during the rest of the process, independently of the manufacturing of the annular body.

[0017] According to other features of the process:

[0018] - the step of making said at least one suspension member includes a sub machining step of the body, prior to the fixing sub-step, during which at least one through opening is made in a radial direction with respect to a main axis of the body, and, during the fixing sub-step, said at least one added element, of dimensions complementary to those of said at least one opening, is welded or brazed into said at least one opening,

[0019] - said at least one added element comprises a plate of complete dimensions comments on those of at least one opening, which is welded into said at least one opening during the fixing substep, and said at least one component of the suspension comprises at least one tab which projects from said plate substantially in a radial direction with respect to a principal axis of the housing and which extends in a plane oriented perpendicularly to the axis of the housing,

[0020] - said at least one suspension member comprises two pairs of two legs pa parallels defining two symmetrically arranged caps on either side of a central tab,

[0021] - the method includes an additional step of milling at least one surface legs designed to cooperate with a complementary component of an aircraft pylon,

[0022] - the plate has a curvature, in a plane perpendicular to an axis of the housing, which is equal to that of the crankcase body,

[0023] - in the plane perpendicular to the axis of the housing, a thickness of the plate in its The middle is greater than the thickness of the longitudinal edges of the plate,

[0024] - during the annular body fabrication step, the following are formed by rolling annular elements projecting from the external surface of the body are then machined on a lathe.

[0025] - the annular elements are fixing flanges and / or stiffeners of said housing.

[0026] The invention also relates to a double-flow turbomachine comprising a fan and, downstream of said fan, a casing of the type described above. Brief description of the figures

[0027] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings in which:

[0028] [Fig-1] [Fig.1] is a cross-sectional view of a turbojet engine;

[0029] [Fig.2] [Fig.2] is an exploded perspective view of an annular housing according to the state of the technique;

[0030] [Fig. 3] [Fig. 3] is a perspective view of an intermediate housing comprising a annular housing according to the invention;

[0031] [Fig.4] [Fig.4] is a half-view in axial section of a body of an annular housing according to the invention;

[0032] [Fig. 5] [Fig. 5] is a perspective view of the body of the annular housing according to the invention;

[0033] [Fig.6] [Fig.6] is a perspective view of the annular housing according to the invention;

[0034] [Fig.7] [Fig.7] is a perspective view of the crankcase suspension components annular according to the invention;

[0035] [Fig.8] [Fig.8] is a half-view in axial section of the annular housing according to the invention;

[0036] [Fig.9] [Fig.9] is a detailed cross-sectional view of the annular housing according to the invention;

[0037] [Fig. 10] [Fig. 10] is a block diagram illustrating the steps of a manufacturing process according to the prior art; and

[0038] [Fig. 11] [Fig. 11] is a block diagram illustrating the steps of a manufacturing process according to the invention. Detailed description of the invention

[0039] Figure 1 shows a turbomachine 10 with a double-flow X-axis or turbojet 10. In a known manner, 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.

[0040] 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.

[0041] The secondary flow S circulates around a core 30 of the turbojet in a secondary channel 32.

[0042] The intermediate housing 14 comprises a hub 32 and an annular housing or ferrule 34 which are connected by outlet guide vanes, also known by the Anglo-Saxon acronym OGV for "outlet guide vanes" and by structural arms 36, which alone have been represented on [Fig.1].

[0043] 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 turbomachine suspension member 46 projecting on an external surface 48 of said body 44.

[0044] Conventionally, these two steps are concomitant and are the subject of a foundry operation.

[0045] 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.

[0046] As can be seen in [Fig. 2], the joining of the angular sectors determines the annular body 44 of the housing 34. One sector 40a of the sectors 40, which is arranged in the upper position of the main body 44 in a position known as the "12 o'clock position" by reference to the position of the hands of a clock at 12 o'clock, includes at least one suspension member 46 of the turbomachine, also cast, which projects onto a external surface 48 of body 44.

[0047] It will therefore be understood that, as illustrated in [Fig. 10], the housing 34 is produced during at least one step ET1 of production of an annular body 44 by casting of the sectors 40 which is concomitant with at least one step ET2 of production by casting of at least one suspension member 46.

[0048] In particular, at least one suspension member 46 comprises two pairs of two parallel lugs 46a defining two yokes 46b arranged symmetrically on either side of a central lug 46c. The yokes 46b and the central lug 46c allow the turbomachine to be suspended, in a known manner, via the intermediate casing 14 and its annular casing 34, from an aircraft pylon, either directly or via a lattice of connecting rods.

[0049] This design is generally satisfactory but has several drawbacks.

[0050] The angular sectors 40 produced by casting are heavy parts, due to the need for sufficient structural rigidity and adequate thickness for subsequent machining. Indeed, welding the edges 42 together requires a minimum thickness for these edges. Furthermore, since these parts are cast, they represent a high industrialization cost, and their machining by milling also entails high costs.

[0051] Finally, the casting, milling, fitting and welding stages of the various angular sectors 40, due to their cumulative durations, generate significant industrialization delays.

[0052] There is therefore a real need for a simplified design of the annular housing housing 34, allowing a reduction in costs and production times.

[0053] The invention remedies these drawbacks by proposing a method for manufacturing an annular housing 34 for a turbomachine, comprising, as before and as illustrated in [Fig. 1 1], at least one step ET1 for producing the annular body 44, and at least one step ET2 for producing at least one turbomachine suspension element 46 projecting from the external surface 48 of said body 44.*

[0054] However, unlike the prior art method, step ET1 of manufacturing the body 44 is carried out by rolling and turning, and step ET2 of manufacturing said at least one suspension member 46 is not carried out concurrently with step ET1 but is carried out after step ET1. Furthermore, step ET2 includes at least one substep SET2 of attaching said body 44 to at least one supporting element 50 of the at least one suspension member 46 by welding.

[0055] Figure 4 illustrates the axial cross-sectional profile of the body 44 of the annular housing 34 obtained after the rolling and turning step. Since this technology is widely known in the prior art, it will not be described further herein. invention. It allows the forming by rolling of annular elements 45 projecting from the external surface 48 of the body 44, then the machining on a lathe of these annular elements 45. These annular elements 45, also visible in [Fig.7], are fixing flanges and / or stiffeners of the housing 34.

[0056] A housing 34 obtained according to this process has been shown in Figures 3, 6 and 7. As can be seen in these figures, and more specifically in [Fig.7], the added element 50 comprises a plate 52 and, as previously described with reference to the prior art, said at least one suspension member 46 comprises at least one lug 46a which projects from said plate 52 substantially in a radial direction R with respect to a principal axis X of the housing and which extends in a plane P oriented perpendicular to the axis X of the housing.

[0057] Preferably, in the annular housing 34 according to the invention, at least one suspension member 46 comprises, as before, two pairs of two parallel tabs 46a defining two yokes 46b arranged symmetrically on either side of a central tab 46c.

[0058] The plate 52 could be fixed directly onto 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.

[0059] To this end, the manufacturing step ET2 of at least one suspension member includes a substep SET1 of machining the body, prior to the fastening substep SET2, during which at least one through opening 54 is made in the radial direction R with respect to the main axis X of the body 44. The plate 52 advantageously has dimensions complementary to the through opening 54 and is welded into the opening 54. Thus, during the fastening substep SET2, said at least one added element 50 is welded or brazed by welding or brazing its plate 52 into said at least one opening 54.

[0060] Fig. 5 illustrates the body 34 in which the through opening 54 has been made by machining, and Fig. 7 represents the added element 50 in position, its plate 52 being welded into the opening 54.

[0061] As can be seen in [Fig.8], 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 [Fig.9], 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.

[0062] In this way the plate 52 does not form an overthickness in relation to the body 44.

[0063] As illustrated in [Fig. 9], the plate 52 has a curvature in the plane P per pendulum to the X axis of the housing 34, which is equal to that of the housing 34. Furthermore, as illustrated in [Fig. 8], a thickness el of the plate 52 in its middle is su 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.

[0064] Advantageously, the plate can also play a role in structural reinforcement. In particular, it can include holes 62 allowing the passage of fixing screws for the upper structural arm 36, known as the "12 o'clock" arm.

[0065] Finally, advantageously, the manufacturing process includes an additional step ET3 of milling functional surfaces of at least one suspension member 46, i.e., the lugs 46a, 46c. More particularly, during this step, at least one surface of each lug 46a, 46c is milled, suitable for cooperating with a complementary member of the pylon or the connecting rod truss of the aircraft.

[0066] The invention therefore makes it possible to simplify the manufacture of an external annular housing 34 of an intermediate housing 14 of a turbomachine.

Claims

Demands

1. A method for manufacturing an annular housing (34) for 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 suspension element (46) for 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 element (46) is carried out after the step (ET1) of producing said body (44) and comprises at least one substep (SET2) of attaching said body to at least one attached element (50) carrying said at least one suspension element (46) by welding, and in that the step (ET2) of producing said at least one suspension element comprises a substep (SET1) of machining of the body (44), prior to the fixation sub-step (SET2),during which at least one through opening (54) is made in the radial direction (R) with respect to a principal axis (X) of the body, and in that, during the fixing sub-step (SET2), said at least one added element (50), of dimensions complementary to those of said at least one opening (54), is welded into said at least one opening (54).

2. A 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 into said at least one opening (54) during the substep (SET2) of fastening, 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) with respect to a principal axis (X) of the housing (34) and which extends in a plane (P) oriented perpendicular to the axis (X) of the housing (34).

3. A manufacturing method according to the preceding claim, characterized in that said at least one suspension member (46) comprises two pairs of two parallel tabs (46a) defining two yokes (46b) arranged symmetrically on either side of a central tab (46c).

4. A manufacturing process according to the preceding claim, characterized in which includes an additional step (ET3) of milling at least one surface of each leg (46a, 46c), said surface being intended to cooperate with a complementary component of an aircraft pylon.

5. A manufacturing method according to any one of claims 2 to 4, characterized in that the plate (52) has a curvature, in a plane (P) perpendicular to an axis (X) of the housing (34), which is equal to that of the body (44) of the housing.

6. A manufacturing method according to any one of claims 2 to 4, characterized in that, in the plane (P) perpendicular to the axis (X) of the housing (34), a thickness (el) of the plate in its middle is greater than a thickness (e2) of longitudinal edges (58) of the plate (60).

7. A method according to any one of the preceding claims, characterized in that, during the step (ET1) of making the annular body (44), annular elements (45) are formed by rolling in projection from the external surface (48) of the body, and then said annular elements (45) are machined on a lathe.

8. Method according to the preceding claim, characterized in that the annular elements (45) are fixing flanges and / or stiffeners of said housing (34).

9. Double-flow turbomachine (10) comprising a blower (12) and, downstream of said blower (12), an annular casing (34) obtained by a process according to one of the preceding claims.