Securing counter plates to composite flanges with rivets and assembly by male-female type fit

Abstract

Counterplate retention on composite flanges with rivets and assembly by male-female type fit. Housing part (10) made of composite material having radial (11) and longitudinal (12) flanges each equipped with radial (13) and longitudinal (14) counterplates respectively, the flanges (11, 12) and counterplates (13, 14) having through holes (15, 16) for the passage of a screw (17) of a bolted assembly intended to assemble the housing part (10) with another part. At least one of the backing plates (13, 14) is fixed by rivets (20), screws (30), or bolts (31) to the flange (11, 12) it equips, while the radial (13) and longitudinal (14) backing plates each have an end (21, 22), these ends (21, 22) of the radial (13) and longitudinal (14) backing plates being mutually assembled by a mechanical fastener (23). Figure to be published with the abbreviation: Figure 4

Description

Title of the invention: Securing plywood to composite flanges with rivets and assembly by male-female fit. TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of turbomachinery for aircraft, for example that of turbojets, turboprops and turbomotors.

[0002] The present invention relates to the retention of plywood on composite flanges of a one-piece housing. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] Aircraft turbomachinery usually includes several casing parts which can serve to protect internal components, provide structural support to the various components, guide and channel airflow, reduce noise and contribute to engine thermal management.

[0004] An example of a casing component 1 is schematically illustrated in [Fig. 1] where the remainder of a turbojet engine 2 is shown in ghost lines. As can be seen in this figure, several casing components 1, usually two, can be joined together to form a substantially tubular casing. Such a casing is generally attached upstream and downstream to other casings or to other components 3, 4 of the turbojet engine 2.

[0005] In order to assemble several casing parts 1 together and with other parts 3, 4 of the turbojet engine 2, the casing parts 1 and the other adjacent parts 3, 4 are provided with mounting flanges 5 which are joined by bolted assemblies, the bolts of which penetrate through through holes 6 distributed along said mounting flanges 5. Among the mounting flanges 5 of the casing parts 1, longitudinal flanges 5a and radial flanges 5b are distinguished. The longitudinal flanges 5a are usually substantially straight or slightly curved, while the radial flanges 5b are usually in the shape of a curvilinear or polygonal arc.

[0006] When the housing parts 1 are made of composite material, the flanges 5 are not directly bolted together. Instead, a piece of plywood 7 having substantially the same shape and dimensions as the mounting flanges 5 is interposed between a flange 5 and a screw or nut of a bolted assembly in order to sandwich the flange 5, as schematically illustrated in [Fig. 2] and [Fig. 3]. The screws of the bolted assemblies (not shown for clarity) enter through through holes 8 distributed along the plywood 7. Naturally, when a piece of plywood 7 is positioned in supported against a flange 5, the through holes 6 and 8 of these are aligned to allow the passage of the screws of the bolted assemblies. For the sake of simplicity, the bolted assemblies are not shown in [Fig. 1] to [Fig. 3].

[0007] As with the mounting flanges 5, longitudinal plywood 7a and radial plywood 7b are distinguished. These plywood 7 hold the mounting flanges 5 together and ensure the mechanical resistance to deformation of the composite mounting flanges 5 at the bolted connections, i.e., under the screw heads and nuts. As a reminder, deformation is a localized plastic deformation of the material under the effect of high pressure.

[0008] Nowadays, the plywood 7 is fixed to the mounting brackets 5 by gluing. The object of the invention is to eliminate the need for glue for this fixing. Summary of the invention

[0009] The invention offers a solution to the problems mentioned above, by allowing not only the plywood to be fixed against the mounting flanges without using glue, but also the plywood to be joined together.

[0010] One aspect of the invention relates to a turbomachine casing component for an aircraft, said casing component being made of composite material and equipped with at least one radial flange and at least one longitudinal flange, said radial and longitudinal flanges each having a first face intended to be fixed against the flange of another part of the turbomachine, and a second face against which a plywood panel is fixed, the at least one radial flange thus being equipped with a radial plywood panel while the at least one longitudinal flange is equipped with a longitudinal plywood panel, the radial and longitudinal flanges as well as the radial and longitudinal plywood panels all having through holes for the passage of a screw of a bolted assembly intended to assemble the casing component with said other part of the turbomachine, the casing component being such that: • a plywood panel, chosen from among the radial and longitudinal plywood panels, is fixed by rivets, screws, or bolts against the respective radial or longitudinal flange it equips, said rivets, screws, or bolts not protruding beyond the first face of said respective radial or longitudinal flange; and • the radial and longitudinal plywood each have one end, these ends of the radial and longitudinal plywood being mutually assembled by a mechanical assembly.

[0011] Fastening a piece of plywood to a composite material flange with rivets, screws, or bolts advantageously eliminates the need for any glue in this fastening. Furthermore, mechanically joining two pieces of plywood at their The mutually contacting ends advantageously allow for the formation of a plywood assembly that can be handled as a single unit during turbomachine maintenance operations. This reduces the number and duration of handling operations when installing and removing the plywood from a composite housing component. Indeed, riveting, screwing, or bolting a plywood piece to a flange serves to hold it against the flange during maintenance operations when bolted assemblies are removed. Finally, when these mutually assembled plywood pieces are installed on a composite housing component, their through-holes are advantageously positioned opposite the through-holes of the flanges against which they rest or in their immediate vicinity.

[0012] According to one aspect of the invention, only one of the radial and longitudinal plywood pieces is fixed by rivets, screws, or bolts to the respective radial or longitudinal flange with which it is fitted. Thus, when one of the two mutually assembled plywood pieces is riveted, screwed, or bolted to a composite material flange, the second plywood piece is also positioned against a composite material flange, without it being necessary to rivet, screw, or bolt it to the first, which notably saves time and reduces the number of rivets, screws, or bolts used, resulting in further savings in material and weight.

[0013] According to another aspect of the invention, the housing part comprises two radial flanges each equipped with a radial plywood and two longitudinal flanges each equipped with a longitudinal plywood, only the two radial plywoods being fixed by rivets, screws or bolts against the radial flanges, each end of the radial plywoods being assembled with one end of the longitudinal plywoods by a mechanical assembly.

[0014] According to a further aspect of the invention, the housing part comprises two radial flanges each equipped with a radial plywood and two longitudinal flanges each equipped with a longitudinal plywood, only the two longitudinal plywoods being fixed by rivets, screws or bolts against the longitudinal flanges, each end of the radial plywoods being assembled with one end of the longitudinal plywoods by a mechanical assembly.

[0015] These two embodiments each allow only two out of four plywood pieces to be riveted, screwed, or bolted, thus providing the advantages described above. Indeed, all the plywood pieces that are not riveted, screwed, or bolted form a single unit that can be advantageously handled as a single piece, and once this unit is placed on a composite housing component, all the plywood pieces are correctly positioned with respect to their Each flange is positioned so that the through holes in all the plywood pieces are aligned with the through holes in their respective flanges for bolting. The entire assembly is then secured to the housing, even if only every other plywood piece is riveted, screwed, or bolted.

[0016] According to one aspect of the invention, a mechanical assembly is a male-female fit, wherein the end of one of the radial and longitudinal plywood pieces has a male portion, and wherein the end of the other plywood piece in contact between the radial and longitudinal pieces has a corresponding female portion to form a mechanical connection between the radial and longitudinal pieces when the male portion is received into the female portion. This type of assembly is advantageously simple, reliable, and quick to implement, and provides an assembly with sufficient mechanical strength to form a plywood unit that can be handled as a single piece.

[0017] According to another aspect of the invention, a mechanical joint is of the mortise and tenon or dovetail type. Indeed, surprisingly, this type of joint, known in the field of woodworking, can advantageously be adapted within the scope of the invention for the assembly of metal plywood.

[0018] According to a further aspect of the invention, a plywood panel fixed by rivets to a flange has through holes for the passage of a rivet equipped with a head. Each of these through holes has a counterbore for a rivet head, the depth of which is such that the rivet head does not protrude beyond these through holes. This counterbore advantageously prevents the rivet head from being damaged, for example, when the plywood panels are machined to bring the flanges back into the desired plane tolerances. It should be noted that usually, only radially mounted plywood panels are machined. During this machining, the plywood panels not riveted to a flange are, for example, held in position by means of clamping clips.

[0019] According to one aspect of the invention, the screws of the bolted assemblies each have a collar located between a head and a threaded shank, and the radial and longitudinal through-holes in the plywood for the passage of a screw in a bolted assembly each have a counterbore for said collar. This counterbore of the bolt holes in the plywood advantageously makes it possible to obtain the best possible flatness for the radial flanges.

[0020] According to another aspect of the invention, each rivet comprises a shank equipped with a head at one end and a tail at the other end, the tail being capable of being deformed in order to be flared or flattened to increase its diameter. This type of rivet is advantageously easy, simple, and quick to install and deform in order to join two parts.

[0021] Another aspect of the invention relates to an aircraft turbomachine equipped with a casing, in which said casing comprises at least one casing part according to the invention as described above.

[0022] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0023] The figures are presented for illustrative purposes only and are not in any way limiting to the invention.

[0024] [Fig.1] is a schematic exploded view of two crankcase parts according to the prior art where the rest of a turbojet engine is represented in ghost lines.

[0025] [Fig.2] is a schematic exploded view of two housing parts according to the prior art, the radial and longitudinal flanges of which are each fitted with plywood.

[0026] [Fig.3] is a schematic detail view at their downstream junction of two housing pieces according to the prior art, the radial and longitudinal flanges of which are each equipped with plywood.

[0027] [Fig.4] is a schematic detail view of an example of a housing part according to the invention, at the junction of a radial plywood with a longitudinal plywood by a mechanical dovetail type assembly.

[0028] [Fig.5] is a schematic detail view of the junction area between the radial flange and the longitudinal flange of the example housing part of [Fig.4].

[0029] [Fig.6] is a schematic detail view of the dovetail type mechanical assembly of the plywood of [Fig.4].

[0030] [Fig.7] is a schematic detail view of an example of a housing part according to the invention, at the junction of a radial plywood with a longitudinal plywood by a mechanical mortise-tenon type assembly.

[0031] [Fig.8] is a schematic detail view of the tenon-mortise type mechanical assembly of the plywood of [Fig.7].

[0032] [Fig.9] is a schematic detail view of an example of a crankcase part according to the invention, at the level of a rivet by which a plywood is fixed against a flange.

[0033] [Fig. 10] is a schematic cross-sectional view along the plane shown in ghost lines on [Fig.9].

[0034] [Fig. 11] is a schematic detail view of an example of a crankcase part according to the invention, at the level of a screw of a bolted assembly by which a flange equipped with plywood is able to be fixed against the flange of another neighboring part (not shown).

[0035] [Fig. 12] is a schematic cross-sectional view along the plane shown in ghost lines on [Fig. 11].

[0036] [Fig. 13] is a schematic detail view of an example of a crankcase part according to the invention, at the level of a screw by which a piece of plywood is fixed against a flange.

[0037] [Fig. 14] is a schematic detail view of an example of a crankcase part according to the invention, at the level of a bolted assembly by which a plywood is fixed against a flange. DETAILED DESCRIPTION

[0038] Unless otherwise specified, the same element appearing on different figures has a unique reference.

[0039] In this application, the terms "upstream" and "downstream" are defined with respect to the direction of airflow in the turbomachine. Similarly, by convention in this application, the terms "inside" and "outside," "lower" and "upper," and "internal" and "external" are defined radially with respect to the longitudinal axis of the turbomachine. Thus, a cylindrical part extending along the engine axis has an inner face facing the longitudinal axis of the turbomachine and an outer surface opposite its inner surface.

[0040] The invention relates to a housing component 10 made of composite material for an aircraft turbomachine. Conventionally, the housing component 10 is equipped with at least one radial mounting flange 11 and at least one longitudinal mounting flange 12. Preferably, it is equipped with two radial mounting flanges 11 and two longitudinal mounting flanges 12. As illustrated in [Fig. 5], the radial and longitudinal flanges 11, 12 are usually integral with the rest of the housing component 10.

[0041] A part of the crankcase 10 according to the invention is partially shown in [Fig.4] and [Fig.7].

[0042] Each radial flange 11 has a first face lia intended to be fixed against the flange of another part of the turbomachine (not shown) by a bolted assembly, and a second face 11b opposite the first face 1 la and equipped with a radial plywood 13 (cf. [Fig.5]).

[0043] Each longitudinal flange 12 has a first face 12a intended to be fixed against the flange of another part of the housing (not shown) by a bolted assembly, and a second face 12b opposite the first face 12a and equipped with a longitudinal plywood 14 (see [Fig.5]).

[0044] Thus, in a conventional manner, the housing piece 10 is equipped with at least one radial plywood 13 and at least one longitudinal plywood 14. It is preferably equipped with two radial plywood 13 and two longitudinal plywood 14.

[0045] In this application, "plywood" means a flange plywood having substantially the same shape and dimensions as the mounting flange against which it is positioned to serve as a support for the screw or nut of a bolted assembly fixing said mounting flange against a mounting flange of another adjacent part, whether that other part is a casing part or another part of the turbomachine.

[0046] As illustrated in [Fig.4], [Fig.6], [Fig.7] and [Fig.8], the radial and longitudinal plywood 13, 14 are separate parts, intended to be mechanically assembled before being placed against their respective flange 11, 12.

[0047] In a conventional manner, the radial flanges 11 and longitudinal flanges 12 have through holes 15. Similarly, the radial plywood 13 and longitudinal flanges 14 have through holes 16, these through holes 16 being located opposite the through holes 15 of the radial flanges 11 and longitudinal flanges 12 for the passage of a screw 17 of the aforementioned bolted assembly.

[0048] A screw 17 of a bolted assembly has a head 17a at one end and a threaded shank 17b extending from this head 17a to the other end, this threaded shank 17b being designed to receive a nut (not shown). A screw 17 of a bolted assembly may also have a collar 17c located between the head 17a and the threaded shank 17b.

[0049] According to a preferred embodiment of the invention illustrated in [Fig.9], [Fig.10], [Fig.11] and [Fig.12], the through holes 16 for the passage of a screw 17 in the flanges 11,12 have a counterbore 29 for the collar 17c of the screws 17. This counterbore 29 ensures the correct flatness of the bearing surface of the collar 17c.

[0050] It will be noted that on [Fig.9] to [Fig. 12], the flange shown can indifferently be a radial flange 11 or longitudinal flange 12, the plywood shown then being respectively a radial plywood 13 or longitudinal plywood 14.

[0051] In addition, the radial flange 11 and longitudinal flange 12 have other through holes 18, and the radial plywood 13 and longitudinal flange 14 have other through holes 19, these through holes 18, 19 being located opposite each other for the passage of the shank 20c of a rivet 20 or the shank 30c of a screw 30.

[0052] By way of example, on [Fig.4] and [Fig.5], only the radial flanges 11 and the radial plywood 13 have through holes 18, 19 for rivet 20 or for screw 30.

[0053] According to another variant not shown, only the longitudinal flanges 12 and the longitudinal plywood 14 have through holes 18, 19 for rivet 20 or for screw 30.

[0054] According to an additional variant, not shown, all the flanges 11, 12 and all the plywood 13, 14 have through holes 18, 19 for rivet 20 or for screw 30.

[0055] The housing part 10 according to the invention is distinguished in that at least one plywood 13, 14 among the radial plywood 13 and longitudinal plywood 14 is fixed by rivets 20, screws 30 or bolts 31 against the radial flange 11 or longitudinal flange 12 respectively which it equips.

[0056] According to one embodiment, only the radial flanges 11 and the radial plywood 13 are joined by rivets 20, screws 30 or bolts 31.

[0057] According to another embodiment, only the longitudinal flanges 12 and the longitudinal plywood 14 are joined by rivets 20, screws 30 or bolts 31.

[0058] According to an additional embodiment, each radial flange 11 and each longitudinal flange 12 is secured to a radial plywood 13 and longitudinal plywood 14 respectively by rivets 20, screws 30 or bolts 31.

[0059] The rivets 20, screws 30 or bolts 31 do not protrude outside the first face 1 of the radial flange 11 or longitudinal flange 12 which they equip so as not to constitute an obstacle between said radial flange 11 or longitudinal flange 12 and the flange of another part of the turbomachine against which it is in contact.

[0060] A rivet 20 comprises a shank 20c equipped with a head 20a at one end and a tail 20b at the other end. This tail 20b is preferably able to be deformed in order to be flared or flattened to increase its diameter. Thus, the tail 20b of the rivets 20 is preferably located on the side of the first face 11a or 12a of the radial flange 11 or longitudinal flange 12 with which they are fitted, while the head 20a of the rivets 20 is preferably located on the side of the second face 11b or 12b of said flange 11, 12.

[0061] According to a preferred embodiment of the invention illustrated in [Fig. 9] to [Fig. 11], the through holes 19 for the passage of a rivet 20 in the plywood 13, 14 have a counterbore 28 for the head 20a of the rivets 20. The depth of these counterbores 28 is chosen so that the head 20a of the rivets 20 does not protrude outside the through holes 19. Indeed, the plywood 13, 14 are usually machined after their assembly on a flange 11, 12, and these counterbores 28 prevent the head 20a of the rivets 20 from being damaged during this machining step of the plywood 13, 14.

[0062] According to variants illustrated on [Fig. 13] and [Fig. 14], the radial plywood 13 and / or longitudinal 14 can also be assembled with the radial flanges 11 and / or longitudinal flanges 12 by a screw 30 or a bolt 31 inserted into the through holes 18, 19, instead of a rivet 20.

[0063] According to the variant illustrated on [Fig. 13], a screw 30, for example of type FHC and / or with a countersunk head 30a, has a shank 30c having an external thread 30b which is complementary to an internal thread 18a, 19a provided in the through holes 18, 19 of the flanges 11, 12 and the plywood 13, 14. Thus, screwing a screw 30 into the through holes 18, 19 of the flanges 11, 12 and the plywood 13, 14 allows these elements to be assembled together.

[0064] According to the variant illustrated in [Fig. 14], the through holes 18, 19 of the flanges 11, 12 and of the plywood 13, 14 do not necessarily have internal threads 18a, 19a, and a threaded nut 32 of a bolt 31 is screwed onto the free end of the screw 30 of said bolt 31. Although it may be similar, this bolted assembly should not be confused with that intended to assemble a part of the housing 10 with another part of the turbomachine.

[0065] According to these two variants, the first face 1 la or 12a of the radial flange 11 or longitudinal flange 12 preferably has a countersink 33 or a counterbore provided to house the head 30a of the screws 30, so that the latter does not protrude outside the through holes 18 of the flanges 11, 12.

[0066] At least one radial plywood 13 and one longitudinal plywood 14 each have an end 21, 22 respectively which are in mutual contact.

[0067] The housing part 10 according to the invention is further distinguished in that its ends 21, 22 are mutually assembled by a mechanical assembly 23. This mechanical assembly 23 is, for example, a male-female type fit, comprising a male part 24 received in a female part 25.

[0068] According to an example of an embodiment illustrated on [Fig.6], the end 22 of a longitudinal plywood 14 has a male part 24, while the end 21 of a radial plywood 13 has a corresponding female part 25 to form a mechanical link between these radial 13 and longitudinal 14 plywoods when the male part 24 is received in the female part 25.

[0069] According to another embodiment illustrated on [Fig.8], it is the end 21 of a radial plywood 13 which has a male part 24, while the end 22 of a longitudinal plywood 14 has a corresponding female part 25.

[0070] Each mechanical assembly 23 can for example be of the tenon-mortise type 27 (see [Fig.7] and [Fig.8]), of the dovetail type 28 (see [Fig.4] and [Fig.6]) or of any other type of male-female fit.

[0071] The invention also relates to an aircraft turbomachine equipped with a casing comprising at least one casing part 10 according to the invention.

[0072] Within such a turbomachine, the casing part 10 according to the invention can for example be a constituent part of a half-shell of a casing made up of two half-shells.

[0073] The housing component 10 according to the invention is, for example, a constituent part of a fan housing or an annular cowling, for example provided between an intermediate housing and an exhaust housing. In this case, its upstream radial flange 11 is bolted to the intermediate housing and its downstream radial flange 11 is bolted to the exhaust housing.

[0074] Although described through a number of examples, variants and embodiments, the crankcase part and the turbomachine according to the invention include various variants, modifications and improvements which will be obvious to a person skilled in the art, it being understood that these variants, modifications and improvements are part of the scope of the invention.

Claims

Demands

1. A turbomachine housing component (10) for an aircraft, said housing component (10) being made of composite material and equipped with at least one radial flange (11) and at least one longitudinal flange (12), said radial flange (11) and longitudinal flange (12) each having a first face (1a) intended to be fixed against the flange of another component of the turbomachine, and a second face (11b) against which a plywood panel (13, 14) is fixed, the at least one radial flange (11) thus being equipped with a radial plywood panel (13) while the at least one longitudinal flange (12) is equipped with a longitudinal plywood panel (14), the radial flange (11) and longitudinal flange (12) as well as the radial plywood panels (13) and longitudinal plywood panels (14) all having through holes (15, 16) for the passage of a screw (17) of a bolted assembly intended to join the housing part (10) with said other part of the turbomachine,The housing part (10) is characterized in that: - a plywood piece (13, 14) from among the radial (13) and longitudinal (14) plywood pieces is fixed by rivets (20), screws (30) or bolts (31) against the radial (11) or longitudinal (12) flange respectively with which it is fitted, said rivets (20), screws (30) or bolts (31) not protruding outside the first face (11a) of said radial (11) or longitudinal (12) flange respectively; and - the radial (13) and longitudinal (14) plywood pieces each have an end (21, 22), these ends (21, 22) of the radial (13) and longitudinal (14) plywood pieces being mutually assembled by a mechanical assembly (23).

2. Casing part (10) according to claim 1, characterized in that a single plywood (13, 14) among the radial (13) and longitudinal (14) plywood is fixed by rivets (20), screws (30) or bolts (31) against the radial (11) or longitudinal (12) flange respectively with which it is fitted.

3. A housing part (10) according to claim 1, characterized in that it comprises two radial flanges (11), each equipped with a radial plywood strip (13), and two longitudinal flanges (12), each equipped with a longitudinal plywood strip (14), only the two radial plywoods (13) being fixed by rivets (20), screws (30) or bolts (31) against the radial flanges (11), each end of the radial plywoods (13) being assembled with one end of the longitudinal plywoods (14) by a mechanical assembly (23).

4. A housing part (10) according to claim 1, characterized in that it comprises two radial flanges (11) each equipped with a radial plywood (13) and two longitudinal flanges (12) each equipped with a longitudinal plywood (14), only the two longitudinal plywoods (14) being fixed by rivets (20), screws (30) or bolts (31) against the longitudinal flanges (12), each end of the radial plywoods (13) being assembled with one end of the longitudinal plywoods (14) by a mechanical assembly (23).

5. A housing part (10) according to any one of the preceding claims, characterized in that a mechanical assembly (23) is a male-female type fit, wherein the end (22, 23) of one of the radial (13) and longitudinal (14) plywoods has a male part (24), and wherein the end (23, 22) of the other plywood (13, 14) in contact among the radial (13) and longitudinal (14) plywoods has a corresponding female part (25) to form a mechanical link between the radial (13) and longitudinal (14) plywoods when the male part (24) is received in the female part (25).

6. Crankcase part (10) according to the preceding claim, characterized in that a mechanical assembly (23) is of the tenon-mortise (26) type or of the dovetail (27) type.

7. A casing part (10) according to any one of the preceding claims, characterized in that a plywood (13, 14) fixed by rivets (20) against a flange (11, 12) has through holes (19) for the passage of a rivet (20) having a head (20a), each of these through holes (19) having a counterbore (28) for a rivet head (20a) of (20) the depth of which is such that the head (20a) of the rivets (20) does not protrude outside of these through holes (19).

8. A housing part (10) according to any one of the preceding claims, characterized in that the screws (17) of the bolted assemblies each have a collar (17c) located between a head (17a) and a threaded rod (17b), and in that the through holes (16) of the radial (13) and longitudinal (14) plywood for the passage of a screw (17) of a bolted assembly have a counterbore (29) for said collar (17c).

9. Crankcase part (10) according to any one of the claims previous, characterized in that the rivets (20) each have a shank (20c) equipped with a head (20a) at one end and a tail (20b) at the other end, the tail (20b) being able to be deformed in order to be flared or flattened in order to increase its diameter.

10. Turbomachine for aircraft equipped with a casing, characterized in that that said housing comprises at least one housing part (10) according to any one of the preceding claims.

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