Injection tool for barrel-shaped rotating parts

Abstract

A tool for injecting polymer resin into a fiber preform to manufacture a rotating part (20) made of composite material includes a barrel shape with a recessed diameter (20CE) of a smaller diameter, defining the rotating part as an upstream portion and a downstream portion of the recessed diameter. The upstream portion includes a middle portion (20B) with an undercut. In this injection tool, in order to allow the barrel-shaped part to be removed from the mold after the polymer resin has been injected and polymerized, the injection tool first includes a tapered shaft (32), which includes a first shaft portion (32A) and a second shaft portion (32B). The first shaft portion is connected to the downstream portion of the rotating part in the recessed diameter. The inner surface (20Ei) of the portion is in direct contact with the outer surface of the rotating component, which is matched with the inner surface (20Di, 20Bi, 20Ai, 20Ci) upstream of the recess diameter. The inner surface of the segmented insert is in direct contact with the second shaft portion on which the segmented insert rests. The first shaft portion includes a natural reverse taper, which allows the central tapered shaft to be pulled out upstream. The inclination of the inner surface of the segmented insert is strictly greater than the maximum slope of the outer surface of the segmented insert, which allows the segmented insert to be pulled out upstream. The outer surface of the segmented insert corresponds to the undercut upstream middle portion of the rotating component.

Description

Technical Field

[0001] This invention relates to the field of composite materials comprising a polymer matrix reinforced by a fiber structure, and more particularly, to the use of such materials in the manufacture of aerospace components or turbines. Background Technology

[0002] In the aerospace industry, there is a desire to maintain high levels of mechanical performance while reducing the mass of engine components. More specifically, in aero turbines, the fan casing, which defines the profile of the engine intake airflow and houses the rotor that supports the fan blades, is now made of composite materials. In its rotating form, it includes a shroud with external clamps at its upstream and downstream ends to secure it to other structural parts of the engine, such as the intake profile upstream and the intermediate casing downstream. The casing also supports various components and must be able to retain debris generated by fan blade breakage or objects sucked in at the engine inlet.

[0003] The manufacture of a fan housing made of composite materials begins by winding a fiber reinforcement onto a mandrel whose profile matches the profile of the housing to be manufactured. For example, the fiber reinforcement can be fabricated using three-dimensional or multi-layer braiding as described in, for instance, patent US 8,322,971. This fiber reinforcement constitutes a tubular fiber preform that forms a single component. Manufacturing continues by densifying the fiber preform with a polymer matrix, including impregnating the preform with resin and polymerizing the resin to obtain the final component.

[0004] More specifically, this invention relates to a manufacturing mode in which a fiber preform is impregnated by an injection molding method called RTM (Resin Transfer Molding). According to this method, the fiber preform is sealed by compacting it in a rigid mold of a fixed geometry, the rigid mold comprising a first portion forming a support for the fiber preform and a counter-mold just deposited on the fiber preform, the shape of the counter-mold corresponding to the desired shell. Resin is injected into the mold under pressure and controlled temperature after bringing the walls of the two mold portions close together and, where appropriate, evacuating them. Once the resin is injected, its polymerization is performed by heating the mold. After injection and polymerization, the final part is demolded, subsequently trimmed to remove excess resin, and machined with chamfers to obtain the desired shell.

[0005] For easy demolding, the injection molding tool, which must be completely sealed, typically includes: a mold with two adjacent inner cylinders that reproduce a flow path with a "diabolo" shape; two upstream and downstream flanges to form the two edges of the shell; and a counter-mold formed by several external sectors. These sectors and the upstream / downstream flanges are removed from the outside. The two inner cylinders are then separated, and the inner cylinders are removed from each side of the shell following the natural flow of the flow path.

[0006] However, in some shell constructions, there is a narrowing of the flow path upstream of the shell, which then takes on a "barrel" shape, for example, evolving from a first diameter upstream to a second, larger diameter in the central region, and then to a third, smaller diameter downstream. Therefore, demolding of any final component is prohibited because it is impossible to remove the upstream barrel. The difference between the small and large diameters can, for example, be between 30 and 100 mm, while the average diameter of the shell can be on the order of 1500 mm to 3500 mm. Summary of the Invention

[0007] Therefore, the objective of this invention is to provide an injection tool for manufacturing composite gas turbine housings with a barrel shape, which allows for demolding in a simple manner, in particular without significantly increasing the number of steps and implementation parts.

[0008] This objective is achieved through a tool for injecting polymer resin into fiber preforms to manufacture composite rotary components, comprising a barrel shape with a smaller inner diameter, defining the rotary component as an upstream and downstream portion of the inner diameter, the upstream portion including a recirculation intermediate portion, wherein, in order to allow demolding of the barrel-shaped component after the injection and polymerization of the polymer resin, the injection tool includes, on one hand, a truncated conical roller comprising a first roller portion and a second roller portion, the first roller portion being the downstream portion of the rotary component within the inner diameter. The inner surface of the first roller is in direct contact with the second roller portion, and the second roller portion rests on the second roller portion. The first roller portion includes a natural vent to allow the truncated conical center roller to be withdrawn from the downstream, and the inclination of the inner surface of the segmented insert is strictly greater than the maximum slope of the outer surface of the segmented insert corresponding to the return middle portion of the rotary component, so as to allow the segmented insert to be withdrawn from the upstream.

[0009] Therefore, demolding of barrel-shaped rotary components can be easily achieved by forming an insert that forms a support and whose engagement slope with the roller is greater than the maximum slope of the inner surface of these barrel-shaped rotary components.

[0010] According to a preferred embodiment, the segmented inserts include at least six, preferably eight, inserts.

[0011] Advantageously, the insert is hollow and is made of impermeable polymer resin by means of a seal.

[0012] According to one embodiment, the tool further includes a substantially radial third roller portion that ensures engagement between the first roller portion and the second roller portion at the inner diameter.

[0013] Preferably, the barrel-shaped rotating component comprises, in sequence between the upstream clamping member and the downstream clamping member: an upstream end portion, a return upstream middle portion, a central portion with a larger diameter, a downstream middle portion, and a downstream end portion.

[0014] Advantageously, the truncated conical center roller is secured to the upstream and downstream flanges by multiple threaded connections. However, the truncated conical center roller and the downstream flange can be formed as a single component.

[0015] Preferably, in order to ensure the radial and angular centering of the segmented insert on the truncated conical central roller, the centering elements are respectively disposed opposite to each other on the segmented insert and the truncated conical central roller.

[0016] Advantageously, the segmented insert is made of a metallic material whose dimensional stability and mechanical properties help to control expansion during polymerization by heating.

[0017] According to a preferred embodiment, the rotating component made of composite material is a fan housing. Attached Figure Description

[0018] Other features and advantages of the invention will become apparent from the following description of specific embodiments of the invention, given by means of non-limiting examples and with reference to the accompanying drawings, in which:

[0019] - Figure 1 This is a perspective view of an aircraft engine, which includes a fan housing obtained from an injection tool according to the invention, and

[0020] - Figure 2 It is permitted to manufacture Figure 1 Axial half-sectional view of the injection tool for the fan housing. Detailed Implementation

[0021] This invention is generally applicable to any rotating component of a gas turbine made of a polymer matrix composite material. However, the invention will be described in the context of its application to the fan casing of an aero gas turbine engine.

[0022] Figure 1An engine is schematically illustrated, comprising, from upstream to downstream, a fan 10, a compressor 12, a combustion chamber 14, a high-pressure turbine 16, and a low-pressure turbine 18 disposed at the engine inlet. The engine includes a continuous housing corresponding to the different engine components, the inner surface of which defines the engine's intake airflow path. Thus, the fan 10 is surrounded by a fan housing 20 having a rotary shape, and this fan housing 20 is made, for example, of a carbon, glass, aramid, or ceramic fiber reinforcement densified, for example, by an epoxy resin, bismaleimide, or polyimide polymer matrix. The fiber reinforcement is achieved in a known manner by three-dimensional or multi-layer weaving (e.g., "interlocking" weaving), while the matrix is ​​achieved via a liquid path according to a known injection method (e.g., the previously mentioned molding method known as RTM).

[0023] The fan housing 20 has external clamps 22 and 24 at its upstream and downstream ends to allow for its installation and connection to other components of the engine (not shown). Between its upstream and downstream clamps, the fan housing is substantially barrel-shaped, including a generally cylindrical central portion 20A with a diameter larger than the generally truncated conical upstream intermediate portion 20B and downstream intermediate portion 20C, which gradually connect to the central portion on both sides along the upstream and downstream slopes, respectively. The upstream intermediate portion 20B is connected to the generally cylindrical upstream end portion 20D, which terminates at the upstream clamp 22, while the downstream intermediate portion 20C is connected at an inner diameter 20CE (specifically, the minimum diameter of the flow path, which defines the upstream and downstream portions of the rotating component as that diameter) to the generally truncated conical downstream end portion 20E, which terminates at the downstream clamp 24. As mentioned earlier, by generating the upstream intermediate portion 20B of the backflow, the larger diameter central portion 20A cannot be achieved using standard RTM injection tools, thus requiring the development of new tools. Furthermore, the presence of two vents facing the smaller diameter makes demolding of the shell impossible.

[0024] Therefore, according to the present invention, in order to solve the problem caused by demolding of a barrel-shaped shell, it is proposed to add a plurality of inserts between the shell support roller and the shell, which fill the non-demolding portion of the shell to make demolding possible again. The roller also has a natural vent in its downstream portion, which facilitates extraction once the inserts are removed.

[0025] Figure 2 A section of the support fan housing 20 of the injection mold according to the invention is shown, which does not have the conventionally closed outer section of the mold reverse mold.

[0026] More specifically, according to the invention, the tool 30 includes a truncated conical central roller 32 held on a drive shaft 33 by a plurality of reinforcing spokes 34, and an upstream flange 36 and a downstream flange 38, the reinforcing spokes preferably being partially perforated to reduce mass. The truncated conical central roller is located on an end portion 32A downstream of the inner diameter 20CE, in direct contact with the inner surface 20Ei of the downstream end portion 20E to allow the roller to withdraw from the downstream along the flow path by natural airflow. The upstream and downstream flanges for molding the outer clamps 22, 24 are fixed to the truncated conical central roller 32, for example, by threaded connection (see reference numeral 39 for the upstream flange; the connection to the downstream flange is outside the cutting plane). It should be noted that the downstream flange 38 and the truncated conical central roller 32 may also be derived from the same component.

[0027] The tool also includes a segmented insert 40 consisting of at least six, typically eight, successive inserts arranged around a central roller 32 to support the fiber preform 20 upstream of the inner diameter 20CE. During assembly, the inserts are placed sequentially on flanges 38 and then laid flat and resting on the central roller 32 due to gravity, which tends to press the inserts against the roller. They are also held angularly and radially by means of centering cones 42 provided on faces 32C. A flange 36 is then added, on which other centering elements 44 apply pressure to the inserts to ensure their eventual holding. Since resin injection is performed under pressure after a vacuum is created in the mold, the inserts must be well regulated with the central roller. The dimensional stability of the materials of the inserts (typically steel) and the roller contributes to successful injection, particularly by controlling expansion during polymerization through heating. Of course, conventional seals (not shown) must also be provided between the different parts of the mold to ensure proper sealing.

[0028] More specifically, the segmented insert, whose outer surface matches the shell portion upstream of the inner diameter 20CE, has an inner surface 32B forming the largest portion of the frustum of the roller 32 (the smallest portion is formed by surface 32A; these two portions of the frustum meet at the inner diameter 20CE via the radial surface 32C forming the recess). Its inclination is strictly greater than that of the upstream intermediate portion 20B, and its upstream slope is the maximum upstream slope of the shell 20 (as shown, the downstream slope of portion 20C can indeed be greater). The inner surfaces 20Ai of the shell portion upstream of the inner diameter 20CE, namely the central portion 20A, the upstream intermediate portion 20B and the downstream intermediate portion 20C, are the inner surfaces 20Bi and 20Ci, and the inner surface 20Di of the upstream end portion 20D. It should be noted that the slope of the inner surface 32B must be forcibly greater than the maximum slope of the side where demolding will be performed (if by, for example, several upstream slopes). Preferably, the side with the lowest slope is selected as the demolding side to specifically prevent the insert from becoming excessively large.

[0029] The injection process during its molding stage is no different from a conventional RTM injection process; the fiber preform is placed in a sealed mold. A low-viscosity thermosetting liquid resin is then injected into the mold to impregnate the entire fiber portion of the preform. Polymerization is then typically performed by heating the mold according to one or more consecutive cycles to achieve the desired degree of densification. Once injection and polymerization are complete, due to tooling modifications, the final part can subsequently be demolded using a simplified procedure compared to that implemented in conventional processes.

[0030] The demolding step differs from the standard step, but is still simplified, because the anti-mold has already been removed in the first demolding step at the end of the polymerization step, so the outer surface of the final part has the outer barrel shape of the shell to be formed; in the second step, simply pull out the upstream flange 36 (after loosening the fastener 39 that connects it to the central roller) to release the segmented insert 40, which can be moved upstream (in Figure 2 The inserts are pulled out one by one (or the first half first, then the second half) along the direction of the ramp 32B, indicated by direction AM. Then, in the next step, the truncated conical center roller 34, either disengaged from or not disengaged from the downstream flange 38 (after possibly loosening the fasteners on the roller), can be pulled out sequentially downstream, indicated by the opposite direction AV, to release the final component, which can then be cut to remove excess resin, thus obtaining the fan housing 20. Alternatively, the roller 32 and flange 38 can be held in place, and the final component can be pulled upstream by any suitable extraction (lifting) means.

[0031] For all these steps, due to their size (several meters in diameter) and mass (several tons), all these components must be handled with care, and therefore it is best to use a crane, belt, or any other similar lifting system for retraction, and then each component of the mold includes the components required for its displacement. These operating components (not shown) include, for example, fastening holes that mate with a tethering ring or any other threaded hole mounted on a nut head. Generally, the technique of operating and fastening large components via tethering rings screwed onto said load is itself a known type relative to systems used for operating heavy and / or bulky loads. However, it should be noted that, in order to reduce the mass of the lifting, the inserts will preferably be hollow, but made completely impermeable to polymer resin (this seal is formed by a seal not shown on face 32), thereby preventing them from being filled with polymer resin during the injection stage.

[0032] It will also be noted that, in order to avoid any deterioration of the final component during the successive extraction steps, the component will preferably be held by means of a processing ring, strip, or any other equivalent means used for processing large-rotation components. Therefore, the final housing component does not include specific components for its operation and is unlikely to deteriorate during this operation.

Claims

1. A tool for injecting polymer resin into a fiber preform to manufacture a composite rotary component, the tool comprising a barrel shape having an inner diameter, the inner diameter being the minimum diameter of a flow path, and defining the rotary component as an upstream portion and a downstream portion of the inner diameter, the upstream portion including an upstream intermediate portion, wherein, To allow demolding of the rotating component immediately after injection and polymerization of the polymer resin, the tool includes, on one hand, a truncated conical center roller comprising a first roller portion and a second roller portion, the first roller portion being in direct contact with the inner surface of the downstream portion of the rotating component; and on the other hand, a segmented insert whose outer surface matches the inner surface of the upstream portion of the rotating component, its inner surface being in direct contact with the second roller portion, the segmented insert resting on the second roller portion; the first roller portion includes a vent to allow extraction of the truncated conical center roller from the downstream, and the inclination of the inner surface of the segmented insert is strictly greater than the maximum slope of the outer surface of the segmented insert corresponding to the upstream middle portion of the rotating component, so as to allow extraction of the segmented insert from the upstream, and wherein the tool includes an upstream flange fastened to the truncated conical center roller and configured for releasing the segmented insert, which can be extracted along the slope of the second roller portion.

2. The tool according to claim 1, characterized in that, The segmented inserts include at least six inserts.

3. The tool according to claim 2, characterized in that, The segmented insert includes eight inserts.

4. The tool according to claim 2, characterized in that, The insert is hollow and is sealed to prevent it from permeating with polymer resin.

5. The tool according to claim 1, characterized in that, The tool also includes a substantially radial third roller section that ensures engagement between the first and second roller sections at the inner diameter.

6. The tool according to claim 1, characterized in that, The rotating component comprises, in sequence between the upstream clamping member and the downstream clamping member: an upstream end portion, an upstream middle portion, a central portion, a downstream middle portion, and a downstream end portion, wherein the diameter of the central portion is larger than that of the upstream middle portion and the downstream middle portion.

7. The tool according to claim 1, characterized in that, The truncated conical center roller is fixed to the upstream and downstream flanges by multiple threaded connections.

8. The tool according to claim 7, characterized in that, The truncated conical center roller and the downstream flange form a single component.

9. The tool according to claim 1, characterized in that, To ensure the radial and angular centering of the segmented insert on the truncated conical central roller, centering elements are respectively arranged opposite to each other on the segmented insert and the truncated conical central roller.

10. The tool according to claim 1, characterized in that, The segmented insert is made of a metallic material whose dimensional stability and mechanical properties help control expansion during polymerization by heating.

11. The tool according to claim 1, characterized in that, The rotating component, made of composite material, is a fan housing.

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