Method for manufacturing a tubular fibrous preform for a part made of composite material
The method of three-dimensional weaving and shaping fibrous skins with specific dimensions and debonding mechanisms addresses the challenge of inserting and adapting tubular preforms into sleeves with variable cross-sections, enabling efficient production of tubular parts for complex engine designs.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- SAFRAN SA
- Filing Date
- 2024-11-22
- Publication Date
- 2026-05-29
AI Technical Summary
Existing methods struggle to insert tubular fibrous preforms into sleeves with variable cross-sections while allowing them to unfold and adapt to different cross-sectional changes, particularly in the production of tubular parts for new generation unfaired engines with variable pitch blades.
A method involving three-dimensional weaving of fibrous skins with specific width and length parts, shaping these skins to form tubular preforms with compact shapes that can be inserted through the smallest section of a sleeve, and deploying to fit larger sections, using debonding mechanisms and beveled edges for flexibility.
Enables easy insertion and deployment of tubular fibrous preforms into sleeves with varying cross-sections, ensuring a compact fit and adaptability for complex engine designs, facilitating the production of tubular parts with enhanced structural integrity.
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Abstract
Description
Title of the invention: Method for manufacturing a tubular fibrous preform for a part made of composite material. Technical field
[0001] The present invention relates to the field of fibrous preforms used to produce parts made of composite material. It relates more particularly to the production of fibrous blanks enabling the manufacture of tubular parts made of composite material. Previous technique
[0002] Tube-shaped composite material parts are used in the aeronautical field. For example, the new generation of unfaired engines (known as "open fan" or "open rotor" engines) requires more compact blade roots. This need arises from the necessity of being able to rotate the blade around its vertical axis in order to adapt its angle of attack to the flight regime (variable pitch blade).
[0003] For this purpose, the feet of the new generation blades have an axisymmetric or substantially axisymmetric shape and reduced dimensions like the blade disclosed in document WO 2023 / 209289.
[0004] The blade foot is formed from a tubular foot preform portion produced by three-dimensional weaving and comprising an internal housing. The foot preform portion is shaped by introducing a metallic internal core into the internal housing of the foot preform portion. An external metallic sleeve is further fixed to the external surface of the foot preform portion.
[0005] Inserting the foot preform part into the external sleeve does not pose a problem when the sleeve has an internal section corresponding to the diameter of the foot preform part.
[0006] However, a new blade design with an external sleeve of variable cross-section is envisaged. In this case, the sleeve comprises at least two parts having different cross-sections. The foot preform portion must therefore be able to adapt to the different cross-sections of the sleeve once it is inserted into the sleeve. In other words, the preform must have a first portion intended to be shaped in the part of the sleeve with the larger cross-section and a second portion intended to be shaped in the part of the sleeve with the smaller cross-section.
[0007] Furthermore, still according to the new blade design envisaged, the portion of the foot preform intended to be shaped in the sleeve portion having the largest cross-section is inserted from the part of the sleeve with the smallest cross-section.
[0008] There is, therefore, a need for a tubular fibrous preform which can be easily inserted into a sleeve through the smallest section thereof while being able to unfold once inserted into the sleeve. Description of the invention
[0009] To this end, the present invention proposes a method for manufacturing a tubular fibrous preform intended to form the fibrous reinforcement of a tubular part made of composite material or of a tubular part of a part made of composite material, the method comprising at least:
[0010] - the realization by three-dimensional weaving of at least the first and second fibrous skins each extending lengthwise along a longitudinal direction and widthwise along a transverse direction, the first and second fibrous skins each comprising at least a first part and a second part adjacent along the longitudinal direction, the first part respectively of the first and second fibrous skins having a width greater than the width of the second part respectively of the first and second fibrous skins, the width of the first and second parts of the first fibrous skin being further less than the external perimeter of a cylinder of predetermined diameter,
[0011] - shaping the first fibrous skin so as to form a first tubular fibrous preform part comprising a first portion of the outer shell of the cylinder of predetermined diameter,
[0012] - shaping the second fibrous skin so as to form a second tubular fibrous preform part comprising a second portion of the outer shell of the cylinder of predetermined diameter, the second portion corresponding to a median portion of the second skin extended on each side by remaining portions of said second skin,
[0013] - the fitting of the second part of the tubular fibrous preform into the first part of tubular fibrous preform so as to form a tubular fibrous preform having an external surface corresponding to the union of the first and second portions of the external envelope of the cylinder of predetermined diameter, the remaining portions of the second skin being folded inside the tubular fibrous preform.
[0014] The tubular fibrous preform thus obtained has a compact shape contained within the cylinder C, the diameter of which can be determined to correspond to the smallest section of an external sleeve into which it is intended to be inserted, while retaining excess lengths suitable for deployment in a portion of outer sleeve having a larger cross-section than the smaller cross-section passage of the latter.
[0015] According to another embodiment of the process of the invention, the first part of the first fibrous skin includes a debonding separating said first part into two layers while the second part of the second fibrous skin includes a debonding separating said second part into two layers.
[0016] According to a particular feature of the process of the invention, the first and second fibrous skins have longitudinal edges in the shape of a bevel.
[0017] According to another particular feature of the process of the invention, the tubular fibrous preform corresponds to a part of the foot preform of a blade or propeller.
[0018] The invention also relates to a method for manufacturing a tubular part comprising:
[0019] - the production of a tubular fibrous preform according to the process of manufacturing according to the invention, the tubular fibrous preform having a determined diameter,
[0020] - the insertion of an internal sleeve into the tubular fibrous preform,
[0021] - the insertion of the fibrous preform into an external shell comprising at least a first section having a first diameter corresponding to the determined diameter of the tubular fibrous preform and a second section having a second diameter greater than the first diameter,
[0022] - the deployment of the first parts of the first and second fibrous skins in the second section of the outer shell,
[0023] - the densification of the tubular fibrous preform with a matrix.
[0024] The invention also relates to a tubular fibrous preform intended to form the fibrous reinforcement of a tubular part made of composite material or of a tubular part of a part made of composite material, the tubular fibrous preform forming a cylinder of determined diameter comprising:
[0025] - a first part of tubular fibrous preform forming a first portion of the outer shell of the cylinder of determined diameter, the first part of tubular fibrous preform having first and second circumferential edges delimiting a space between them,
[0026] - a second part of tubular fibrous preform forming a second portion of the outer envelope of the cylinder of determined diameter present in the space delimited by the first and second circumferential edges of the first part of tubular fibrous preform, the second portion of the outer envelope of the cylinder of predetermined diameter extending on each side by extension portions folded inside the first part of tubular fibrous preform.
[0027] The tubular fibrous preform of the invention has a compact shape contained within a cylinder whose diameter can be determined to correspond to the smallest section of an external sleeve into which it is intended to be inserted while retaining excess lengths suitable for being deployed in a portion of the external sleeve having a larger cross-section than the reduced cross-section passage of the latter.
[0028] According to a particular feature of the preform of the invention, the first part of the tubular fibrous preform includes a debonding separating said first part into two layers while the second part of the tubular fibrous preform includes a debonding separating said second part into two layers.
[0029] According to another particular feature of the preform of the invention, the first and second parts of the tubular fibrous preform have longitudinal edges in the shape of a bevel.
[0030] According to another particular feature of the preform of the invention, the first and second parts of the tubular fibrous preform each have a three-dimensional weave.
[0031] The invention further relates to a tubular part made of composite material comprising a tubular fibrous preform according to the invention densified by a matrix. Brief description of the drawings
[0032] [Fig-1] Fig. 1 is a schematic view of a first fibrous skin used for the manufacture of a tubular preform according to an embodiment of the invention,
[0033] [Fig.2] Fig.2 is a schematic view of a second fibrous skin used for manufacturing a tubular preform according to one embodiment of the invention.
[0034] [Fig.3] The [Fig.3] is a schematic view from below of the first fibrous skin of the [Fig.1],
[0035] [Fig.4] The [Fig.4] is a schematic top view of the second fibrous skin of the [Fig.2],
[0036] [Fig.5] Fig.5 is a schematic perspective view showing the formation of a first part of the tubular preform from the first fibrous skin of Figures 1 and 3,
[0037] [Fig.6] [Fig.6] is a schematic perspective view showing the compaction of the first part of the tubular preform of [Fig.5],
[0038] [Fig.7] Fig.7 is a schematic perspective view of a first part of a tubular preform,
[0039] [Fig-8] Fig. 8 is a schematic perspective view of a second part of a tubular preform.
[0040] [Fig. 9] Fig. 9 is a schematic perspective view of a tubular fibrous preform formed with the first and second preform parts of Figures 7 and 8,
[0041] [Fig. 10] Fig. 10 is a schematic perspective view of a first tubular preform part according to another embodiment,
[0042] [Fig. 11] Fig. 11 is a schematic perspective view of a second part of a tubular preform according to another embodiment,
[0043] [Fig. 12] The [Fig. 12] is a schematic perspective view of a tubular fibrous preform formed with the first and second preform parts of Figures 10 and 11. Description of the implementation methods
[0044] The invention applies generally to the manufacture of fibrous blanks intended to form fibrous preforms or parts of tubular preforms that serve as reinforcements for tubular parts or parts of parts made of composite material. The invention finds an advantageous, but not exclusive, application in the manufacture of blade roots or propellers for unfaired rotating wheels, such as those found in so-called "open rotor" aircraft engines.
[0045] In the following description, the embodiments are described in relation to the manufacture of a blade or propeller for unshod, rotating wheels of a turbomachine. However, the embodiments also apply to tubular parts intended for other applications.
[0046] Figures 1 to 4 show very schematically first and second fibrous skins 100 and 200 intended to form the tubular fibrous preform to be produced.
[0047] The fibrous skins 100 and 200 are obtained by three-dimensional (3D) weaving carried out in a known manner using a Jacquard-type loom on which a bundle of warp yarns or strands is arranged in a plurality of layers, the warp yarns being linked by weft yarns. The fibrous skins 100 and 200 are woven in a single piece. The 3D weave may, in particular, be an interlock weave. By interlock weave, we mean a weave structure in which each layer of weft yarns links several layers of warp yarns with all the yarns in the same weft column having the same movement in the plane of the weave. Other known types of three-dimensional weaves may be used, such as those described in document WO 2006 / 136755. The fibrous blank according to the invention may be woven, in particular, from carbon fiber yarns or ceramic yarns such as silicon carbide.
[0048] The fibrous skins 100 and 200 each have a flat shape. In the example described here, the first fibrous skin 100 comprises first and second parts 110 and 120 adjacent along the longitudinal direction DL (Figures 1 and 3). The first part 110 extends over a length Ln0 along the longitudinal direction DL and over a first width l110 along the transverse direction DT, while the second part 120 extends over a length Li20 along the longitudinal direction DL and over a second width li20 along the transverse direction DT. The second width li20 is less than the first width l110.
[0049] Similarly, in the example described here, the second fibrous skin 200 comprises first and second parts 210 and 220 adjacent along the longitudinal direction DL (Figures 2 and 4). The first part 210 extends over a length L2i0 along the longitudinal direction DL and over a first width l2i0 along the transverse direction DT, while the second part 220 extends over a length L220 along the longitudinal direction DL and over a second width l220 along the transverse direction DT. The second width l220 is less than the first width l2i0.
[0050] The fibrous skins may comprise more than two parts, the number of parts being defined in particular according to the geometry and dimensions of the part in composite material to be produced.
[0051] In the example described here, the first and second parts 110 and 120 of the first fibrous skin have longitudinal edges 111, 112, 121, and 122 in the shape of a bevel, also called a "scarf" in English. Similarly, the first and second parts 210 and 220 of the second fibrous skin have longitudinal edges 211, 212, 221, and 222 in the shape of a bevel, also called a "scarf" in English. This beveled shape is obtained during the weaving of the skins by progressively bringing layers of warp yarns out at the lateral edges of the fibrous skins. Each beveled lateral edge of one of the fibrous skins is designed to cooperate with a beveled lateral edge of the other fibrous skin in order to maintain continuity in the thickness of the formed fibrous preform.The invention is not limited, however, to longitudinal edges in the shape of a bevel; these can also be straight or have other complementary shapes, for example stepped, allowing for overlap of the edges in contact.
[0052] The first and second fibrous skins 100 and 200 are intended to form respectively the first and second parts of a tubular fibrous preform.
[0053] Figure 7 shows a first part 310 of tubular fibrous preform obtained by shaping the first fibrous skin 100. As illustrated in Figures 5 and 6, the first fibrous skin 100 is shaped in a tool 400. The first skin 100 is first wound onto a counter-form 450 before being placed in the tooling 400. The tooling 400 includes a lower wedge 410, an upper wedge 420, a first lateral wedge 430 and a second lateral wedge 440 between which the first fibrous skin 100 and the counter-form 450 are placed. In the example described here, the lower wedge 410, the upper wedge 420, the first lateral wedge 430 and the second lateral wedge 440 each have a groove-shaped cavity 411, 421, 421 and 441 respectively, cooperating with a portion of the outer surface of the first fibrous skin 100 or of the counter-form 450 (for the upper wedge 420).
[0054] Once the tooling 400 is assembled around the first fibrous skin 100 and the counter-form 450, the shaping of the first part 310 of the tubular fibrous preform is completed while being compacted as illustrated in [Fig. 6]. For this purpose, a compaction pressure Pc is applied to each of the shims, which allows the preform part 310 to be compacted in four directions. The shims are designed with reference marks to determine their exact position relative to the fibrous preform and thus control the level of compaction applied and, consequently, the fiber volume fraction in the preform. The compaction force can be applied by using presses on the shims or by clamping the shims. As an example, the compaction pressure Pc applied to each shim can be 15 bar, which makes it possible to achieve a fiber volume fraction of approximately 60%.
[0055] The first fibrous skin 100 is moistened with water before compaction, i.e. before or after placement around the counter-form 450. The water acts as a lubricant which facilitates sliding between the yarns, which reduces disturbances or disruptions to the initial weave during shaping and compaction.
[0056] The first portion of the tubular fibrous preform, held in its shape and compacted state within the holding tooling, is placed in an oven or similar device to dry it, for example, at a temperature of 120°C for a 12-hour cycle. In addition to facilitating sliding between the fibers during compaction, moistening the first portion of the preform allows the sizing present in the fibers to dissolve and diffuse into the blank. Drying the first portion of the tubular fibrous preform removes the water present within it and solidifies it in its compacted state through the hardening of the sizing, even after its removal from the tooling.
[0057] As illustrated in [Fig. 7], a first portion 310 of tubular fibrous preform is obtained which fits within a cylinder C of a determined diameter D. The cylinder C corresponds to the intended template for the tubular fibrous preform, the diameter D of the cylinder C corresponding to the smallest cross-section of an external sleeve (not shown in [Fig. 7]) through which the tubular fibrous preform is intended to pass during its insertion into the sleeve. In other words, the first part 310 of tubular fibrous preform forms a first portion 314 of the outer envelope of the cylinder C. The first part 310 of tubular preform comprises a first partially cylindrical part 311 corresponding to the first part 110 of the shaped fibrous skin 100 and a second partially cylindrical part 312 corresponding to the second part 120 of the first shaped fibrous skin 100.
[0058] The first part 311 of the first part 310 of the tubular preform comprises two circumferential edges 3111 and 3112 corresponding to the lateral edges 111 and 112 of the first fibrous skin 100 and delimiting between them a space E. The second part 312 of the first part 310 of the tubular preform comprises two circumferential edges 3121 and 3122 corresponding to the lateral edges 221 and 222 of the first fibrous skin 100 and delimiting between them a space E. The space E is variable between the first and second parts 311 and 312 of the first part 310 of the fibrous preform.
[0059] Figure 8 shows a second part 320 of a tubular fibrous preform obtained by shaping the second fibrous skin 200. The second fibrous skin 100 is shaped in a tool similar to the tool 400 described previously (not shown in Figure 8). As explained previously for shaping the first skin 100, the second skin 200 is first wound onto a counter-form (not shown in Figure 8) before being placed in the tool, which, like the tool 400, comprises a lower wedge, an upper wedge, a first lateral wedge, and a second lateral wedge between which the second fibrous skin and the counter-form are placed. Once the tool is assembled around the second fibrous skin and the counter-form, the shaping of the second part 320 of the tubular fibrous preform is completed while simultaneously compacting it.As an example, the compaction pressure applied to each of the wedges can be 15 bars, which makes it possible to achieve a fiber volume percentage of approximately 60%.
[0060] The second fibrous skin 200 is moistened with water before compaction, i.e., before or after being placed around the counter-form. The water acts as a lubricant that facilitates sliding between the fibers, thus reducing disturbances or disruptions to the initial weave during shaping and compaction.
[0061] The second part of the tubular fibrous preform, held in shape and compacted within the holding tooling, is placed in an oven or similar device to dry it, for example, at a temperature of 120°C for a 12-hour cycle. In addition to facilitating sliding between the fibers during compaction, moistening the second part of the preform allows the sizing present in the fibers to dissolve and diffuse into the blank. The drying of the second part The tubular fibrous preform allows the water present in it to be removed and it to be fixed in its compacted state by the hardening of the sizing even after its removal from the tooling.
[0062] As illustrated in [Fig. 8], a second portion 320 of tubular fibrous preform is obtained, which fits into the cylinder C. As indicated above, this cylinder C corresponds to the intended template for the tubular fibrous preform. The diameter D of the cylinder C corresponds to the smallest cross-section of an external sleeve (not shown in [Fig. 8]) through which the tubular fibrous preform is intended to pass during its insertion into the sleeve. The second portion 320 of tubular preform comprises a first portion 321 corresponding to the first portion 210 of the second shaped fibrous skin 200 and a second portion 322 corresponding to the second portion 220 of the second shaped fibrous skin 200.
[0063] The first portion 321 of the second portion 320 of the tubular fibrous preform comprises a median portion 3210 forming a cylindrical section. Similarly, the second portion 322 of the second portion 320 of the tubular fibrous preform comprises a median portion 3220 forming a cylindrical section. The median portions 3210 and 3220 together form a second portion 324 of the outer shell of the cylinder C. The median portion 3210 is extended on each side by folded first and second extension portions 3211 and 3212 corresponding respectively to the remaining portions of the first portion 210 of the second fibrous skin 200.
[0064] Once the first and second parts 310 and 320 of the tubular fibrous preform have been formed and compacted, the second part 320 is fitted into the first part 310 so as to form a tubular fibrous preform 300 as shown in [Fig. 9]. The tubular fibrous preform 300 has an external surface corresponding to the union of the first portion 314 of the outer shell of cylinder C formed by the first part 310 and the second portion 324 of the outer shell of cylinder C formed by the middle portions 3210 and 3220 of the second part 320 of the preform.
[0065] The tubular fibrous preform 300 thus obtained has a compact shape contained within the cylinder C, the diameter of which has been determined to correspond to the smallest cross-section of an external sleeve into which it is intended to be inserted, while retaining excess lengths suitable for deployment in a portion of the external sleeve having a larger cross-section than the reduced cross-sectional passage of the latter. In the example described here, the first portion 310 of the tubular fibrous preform 300 is intended to be placed and deployed in the portion of an external sleeve having the largest cross-section thereof, while the second portion 320 of The tubular fibrous preform is intended to be placed in the part of the outer sleeve having a smaller cross-section.
[0066] Thus, and as shown in [Fig. 9], the tubular fiber preform 300 comprises the first and second extension parts 3211 and 3212 of the second part 320 folded inside the tubular fiber preform 300, as well as the first and second extension parts 3113 and 3114 of the first part 310 also folded inside the tubular fiber preform 300. Once the preform 300 is fully inserted into the outer sleeve, the extension parts 3113, 3114, 3211 and 3212 can be deployed to conform to a portion of the sleeve having a cross-section larger than the diameter D of the cylinder C.
[0067] Figures 10 and 11 show, respectively, a first portion 510 of a tubular fibrous preform and a second portion 520 of a tubular fibrous preform according to another embodiment. The first and second portions 510 and 520 of the tubular fibrous preform differ from the first and second portions 310 and 320 of the tubular fibrous preform in that they each have a debonding mechanism allowing separation into two layers. More specifically, the first portion 511 of the first portion 510 of the preform has a debonding mechanism d1 that separates said first portion 511 into two layers 5110 and 5111 ([Fig. 10]). Similarly, the first portion 521 of the second portion 520 of the preform has a debonding mechanism d2 that separates said first portion 521 into two layers 5211 and 5212 ([Fig. 11]).
[0068] The unbindings d1 and d2 are made during the weaving of the fibrous fibers from which the first and second parts 510 and 520 of the tubular fibrous preform are formed. In a known manner, an unbinding can be formed during 3D weaving between two sets of warp yarn layers. Layers of warp yarns are bound together by weft yarns forming a first set of yarn layers, while other layers of warp yarns are bound together by two weft yarns forming a second set of yarn layers. The weft yarns present in the first set of yarn layers do not extend into the warp yarn layers of the second set of yarn layers, and vice versa, which ensures an unbinding that separates the sets of yarn layers from each other. Two woven portions, independent of each other, are thus formed on either side of the unbinding.
[0069] In accordance with the invention and as described above, the first portion 510 of the tubular fiber preform comprises first and second portions 511 and 522 which form a first portion 514 of the outer shell of a cylinder C ([Fig. 10]). The second portion 520 of the tubular fiber preform comprises first and second portions 521 and 522 which also fit within the cylinder C ([Fig. 11]), which corresponds to the intended template for the tubular fiber preform so that it can pass through the smallest cross-section of an outer sleeve. The first Part 521 of the second part 520 of the tubular fibrous preform includes a central portion 5210 forming a cylindrical portion. Similarly, the second part 522 of the second part 520 of the tubular fibrous preform includes a central portion 5220 forming a cylindrical portion. The central portions 5210 and 5220 together form a second portion 524 of the outer shell of the cylinder C. The central portion 5210 is extended on each side by folded first and second extension portions 5213 and 5214.
[0070] Once the first and second parts 510 and 520 of the tubular fibrous preform have been formed and compacted, the second part 520 is fitted into the first part 510 so as to form a tubular fibrous preform 500 as shown in [Fig. 12]. The tubular fibrous preform 500 has an external surface corresponding to the union of the first portion 514 of the outer shell of the cylinder C formed by the first part 510 and the second portion 524 of the outer shell of the cylinder C formed by the middle portions 5210 and 5220 of the second part 520 of the preform.
[0071] The tubular fibrous preform 500 thus obtained has a compact shape contained within the cylinder C, the diameter of which has been determined to correspond to the smallest cross-section of an external sleeve into which it is intended to be inserted, while retaining excess lengths suitable for deployment in a portion of the external sleeve having a larger cross-section than the reduced cross-sectional area of the latter. In the example described here, the first portion 510 of the tubular fibrous preform 500 is intended to be placed and deployed in the portion of the external sleeve having the largest cross-section, while the second portion 520 of the tubular fibrous preform is intended to be placed in the portion of the external sleeve having a smaller cross-section.
[0072] Thus, and as shown in [Fig. 12], the tubular fibrous preform 500 comprises the first and second extension portions 5213 and 5214 of the second portion 520 folded inside the tubular fibrous preform 500, as well as the first and second extension portions 5113 and 5114 of the first portion 510 also folded inside the tubular fibrous preform 500. Once the preform 500 is fully inserted into the outer sleeve, the extension portions 5113, 5114, 5213 and 5214 can be deployed to conform to a portion of the sleeve having a cross-section larger than the diameter D of the cylinder C.
[0073] Furthermore, thanks to the presence of the dl and d2 debonds, an object, such as a ring, can be placed between, on the one hand, layers 5111 and 5212 and layers 5110 and 5211, on the other hand.
[0074] The tubular fiber preform 300 or 500 can be used to produce a tubular part made of composite material. For this purpose, the tubular fiber preform 300 or 500 is densified to obtain a tubular part made of composite material. The densification of the fibrous preform intended to form the fibrous reinforcement of the part to be manufactured consists of filling the porosity of the preform, in all or part of its volume, with the material constituting the matrix.
[0075] This densification can be achieved, in a known manner, by the liquid-based process (LBC, "LCM" in English). The liquid-based process consists of impregnating the preform with a liquid composition containing a precursor of the matrix material. The precursor is usually in the form of a polymer, such as a high-performance epoxy resin, possibly diluted in a solvent.
[0076] The transformation of the precursor into a matrix, namely its polymerization, is carried out by heat treatment, generally by heating the injection tooling, after removal of any solvent and crosslinking of the polymer, the preform always being held in the molding cavity having a shape corresponding to that of the part to be produced.
[0077] According to one aspect of the invention, the densification of the fibrous preform can be achieved by the well-known resin transfer molding (RTM) process. According to the RTM process, the fibrous preform is placed in a mold having the external shape of the part to be produced. A thermosetting resin is injected into the internal space of the mold containing the fibrous preform. A pressure gradient is generally established in this internal space between the point where the resin is injected and the resin discharge ports in order to control and optimize the impregnation of the preform by the resin.
[0078] The resin used can be, for example, an epoxy resin with a temperature class of 180 °C (maximum temperature that can withstand it without loss of properties). Resins suitable for RTM processes are well known. They preferably have a low viscosity to facilitate their injection into the fibers. The choice of temperature class and / or the chemical nature of the resin is determined according to the thermomechanical stresses to which the part must be subjected. Once the resin has been injected throughout the reinforcement, it is polymerized by heat treatment according to the RTM process.
[0079] After injection and polymerization, the part is demolded. Finally, the part can be trimmed to remove excess resin and the chamfers are machined.
[0080] Other known densification and / or matrix precursor processes can also be used to manufacture the part in composite material.
[0081] In the example described here, the fibrous tube preform 300 or 500 is intended for manufacturing a blade or propeller root made of composite material for unfaired turbine wheels of a turbomachine. In this case, the fibrous preform may be a portion of the root preform located in the extension of a portion of the blade preform of a fibrous blade or propeller preform. Also in the case of manufacturing a blade or propeller root from composite material for unfaired turbine wheels of a turbomachine, a metallic internal core is introduced into the internal cavity of the tube preform. Furthermore, the tubular preform with its internal core is then inserted into an external sleeve, for example, made of metal, to allow the blade or propeller to be integrated into a rotor disk. The preform with its internal core and external sleeve is then densified as described above.
Claims
1. Demands A method for manufacturing a tubular fibrous preform (300) intended to form the fibrous reinforcement of a tubular part made of composite material or of a tubular portion of a part made of composite material, the method comprising at least: - the realization by three-dimensional weaving of at least the first and second fibrous skins (100, 200) each extending lengthwise along a longitudinal direction (DL) and widthwise along a transverse direction (DT), the first and second fibrous skins each comprising at least a first part (110, 210) and a second part (120, 220) adjacent along the longitudinal direction, the first part (110, 210) respectively of the first and second fibrous skins having a width (ln0, l2io) greater than the width (l^o, l220) of the second part (120, 220) respectively of the first and second fibrous skins (100, 200), the width of the first and second parts of the first fibrous skin being further less than the external perimeter of a cylinder (C) of predetermined diameter (D), - shaping the first fibrous skin (100) so as to form a first part (310) of tubular fibrous preform comprising a first portion (314) of the outer shell of the cylinder of predetermined diameter, - shaping the second fibrous skin (200) so as to form a second part (320) of tubular fibrous preform comprising a second portion (324) of the outer shell of the cylinder of predetermined diameter, the second portion (324) corresponding to a median portion (3210) of the second skin (200) extended on each side by remaining portions (3211, 3212) of said second skin, - the fitting of the second part (320) of tubular fibrous preform into the first part (310) of tubular fibrous preform so as to form a tubular fibrous preform (300) having an external surface corresponding to the union of the first and second portions (314, 324) of the external envelope of the cylinder (C) of predetermined diameter (D), the remaining portions (3211, 3212) of the second skin (200) being folded inside the tubular fibrous preform.
2. A method according to claim 1, wherein a first part of the first fibrous skin comprises a debonding separating said first part into two layers while the second part of the second fibrous skin comprises a debonding separating said second part into two layers.
3. A method according to claim 1 or 2, wherein the first and second fibrous skins (100, 200) have longitudinal edges (111, 112, 121, 122, 211, 212, 221, 222) in the shape of a bevel.
4. A method according to any one of claims 1 to 3, wherein the tubular fibrous preform (300) corresponds to a preform foot portion of a blade or propeller.
5. A method for manufacturing a tubular part comprising: - producing a tubular fibrous preform (300) according to the manufacturing method according to any one of claims 1 to 4, the tubular fibrous preform having a determined diameter, - inserting an internal sleeve into the tubular fibrous preform, - inserting the fibrous preform into an external shell comprising at least a first section having a first diameter corresponding to the determined diameter of the tubular fibrous preform and a second section having a second diameter greater than the first diameter, - deploying the first parts of the first and second fibrous skins in the second section of the external shell, - densifying the tubular fibrous preform with a matrix.
6. A tubular fiber preform (300) intended to form the fibrous reinforcement of a tubular part made of composite material or of a tubular portion of a part made of composite material, the tubular fiber preform forming a cylinder (C) of a determined diameter (D) comprising: - a first portion (310) of tubular fiber preform forming a first portion (314) of the outer shell of the cylinder of determined diameter, the first portion (310) of tubular fiber preform having first and second circumferential edges delimiting between them a space (E), - a second portion (320) of tubular fiber preform forming a second portion (324) of the outer shell of the cylinder (C) of determined diameter (D) present in the space (E) delimited by the first and second circumferential edges of the first part (310) of tubular fibrous preform, the second portion (324) of the external envelope of the cylinder of predetermined diameter extending on each side by extension portions (3211, 3212) folded inside the first part (310) of tubular fibrous preform.
7. Preform according to claim 6, wherein the first part (510) of tubular fibrous preform comprises a debonding (di) separating said first part into two layers (5110, 5111) while the second part (520) of tubular fibrous preform comprises a debonding (d2) separating said second part into two layers (5211, 5212).
8. Preform according to claim 6 or 7, wherein the first and second parts (310, 320) of tubular fibrous preform have longitudinal edges in the shape of a bevel.
9. Preform according to any one of claims 6 to 8, wherein the first and second parts (310, 320) of tubular fibrous preform each have a three-dimensional weave.
10. Tubular part in composite material comprising a tubular fibrous preform (300, 500) according to any one of claims 6 to 9 densified by a matrix.