EP2874799A1

EP2874799A1 - Method for manufacturing a t-shaped composite part by resin-transfer moulding

Info

Publication number: EP2874799A1
Application number: EP13744738.9A
Authority: EP
Inventors: Didier LERETOUR; Sébastien LOUCHARD; Laurent Dubois; Claire DUPUIS
Original assignee: Aircelle SA
Current assignee: Safran Nacelles SAS
Priority date: 2012-07-20
Filing date: 2013-07-12
Publication date: 2015-05-27
Also published as: BR112015001202A2; FR2993492B1; CN104470707A; WO2014013167A1; RU2015105002A; CA2879135A1; US20150125654A1; FR2993492A1

Abstract

The invention relates to a method for manufacturing a T-shaped composite part by resin-transfer moulding, which includes the steps involving: creating a preform having a substantially planar stack (A) of plies and having two L-shaped stacks (B, C) of plies; placing said preform such that said L-shaped stacks L (B, C) meet between two cores (M1, M2) of a resin-transfer moulding tool (M); inserting and removing fibres through said planar stack (A) in a direction perpendicular or quasi-perpendicular to said stack (A) and such as to form loops (b) inside the portions (81, 82) of said L-shaped stacks (B, C) that are substantially perpendicular to said planar stack; closing the moulding tool (M); injecting the resin into the moulding tool (M); and heating the moulding tool (M) in order to cure the resin.

Description

Method of manufacturing a T composite part by resin transfer molding

The present patent application relates to the field of the fa b io n d e p e cies e n m ate ri a u x com posites, in particular for aeronautics.

As is known per se, it is possible to produce composite material parts from fabrics (frequently called "plies") of fibers, especially of carbon or glass, which are impregnated with resin (polyimide for example) which is then polymerizes by raising the temperature in autoclaves.

In this way, parts are obtained which can have practically any geometry, as well as an excellent compromise between strength and weight.

Various resin impregnation techniques exist: pre-impregnated plies of resin can be used, or resin transfer methods can be used.

Such methods, commonly used for the manufacture of parts in aeronautics, are designated generically by RTM ("Resin Transfer Molding").

This technique consists in placing a preform constituted by a ply assembly inside an enclosed mold, in which resin is injected under pressure. This resin thus progresses through the folds, and gradually fills all the gaps available. Once this filling is completed, the temperature of the mold is raised so as to harden the resin.

This technique is used in particular for the manufacture of T-pieces, that is to say pieces comprising two sections 1, 2 substantially perpendicular to each other, as can be seen in FIGS. 1 and 2 below. attached.

Such parts can be used especially for the manufacture of beams.

More specifically, to manufacture such a piece, three em pilings of pl is used: a substantially plane stack A, and two stacks substantially L, B and C, the latter two being joined so as to define the foot of the T.

When the preform constituted by the stacks A, B and C is impregnated with resin, the formation of a cluster of resin 3 is commonly found in the junction zone of these three stacks.

This resin mass, devoid of fibers, is a weak point of the part obtained in fine: it can indeed be at the origin of a delamination of the surrounding folds, and limits the resistance to tensile stresses tending to separate the stacks B and C of the stack A (arrow 5 in FIGS. 1 and 2).

To remedy these drawbacks, two solutions are used to date.

The first solution is to pre-fill the junction area of the three stacks of a set of fibers held together: this solution, called "nail head" with respect to the shape of the cross section of said junction area , causes many difficulties in the context of an industrial process. By way of example, the added fibers can move during the resin injection, and finally occupy positions that are not optimal with respect to resistance to external forces.

The second solution is to sew between them the stacks A, B, C in their junction area, as can be seen in Figure 2 (stitches 7). This solution has the disadvantage of being able to be implemented only before introduction of the preform constituted by the stacks A, B, C on the RTM mold, the latter comprising in particular two metal cores preventing passage of the needles. sewing at the appropriate places. In addition, this seaming solution in practice makes it possible to increase only slightly the resistance to tensile stresses tending to separate the stacks B and C from the stack A.

The present invention is thus particularly intended to provide a method of manufacturing a composite T-piece by resin transfer molding, that it is easily industrial isable and has a resistance improved vis-à-vis efforts to separate the two sides of the T from each other.

This object of the invention is achieved with a method of manufacturing a T composite part by resin transfer molding, comprising the steps of:

constituting a preform with a stack substantially plane folds and with two stacked L folds,

placing said preform so that said L-shaped stacks are between two cores of a resin transfer molding tool,

- Entering and removing fibers through said stack plane in a direction perpendicular or quasi-perpendicular to this stack and so as to form loops inside the parts of said stacks e n L which are substantially perpendicular to said stack plane,

- close the molding tool,

- injecting resin into the molding tool, and

- Heat the molding tool to harden the resin.

Thanks to this process in which the fibers enter and exit on the same face of the fold plane stack, it is therefore possible to consolidate the junction zone of the various stacks of the preform once it has been placed between the cores of the molding tool, which is much simpler to implement in the context of an industrial process: the movements of the sewing machine making the fiber loops can indeed be limited to linear movements.

In addition, the orientation of the fibers forming the loops perpendicularly to the fold plane stack, and the passage of these fibers in the parts of the L-shaped stack of folds which are substantially perpendicular to the fold plane stack is that is, in fact in the foot of the T, offers a particularly remarkable resistance with respect to the efforts that tend to pull the L-shaped stacks of the plane stack. According to other optional features of the method according to the invention:

said flat stack and said L-shaped stacks are assembled prior to the introduction of the preform between the two cores of the molding tool;

said L-shaped stacks are assembled, introduced between the two cores of the molding tool, and covered with said plane stack;

positioning each of said L-shaped stacks and said plane stack one after the other in the molding tool;

- loops of different lengths are formed;

- loops are formed slightly inclined relative to the direction perpendicular to said stack plane;

a first and a second group of loops are formed, the length and inclination of said first group of loops with respect to the direction perpendicular to said plane stack being greater than those of said second group of loops.

The present invention also relates to a composite part obtained from the aforementioned method.

Other characteristics and advantages of the present invention will emerge in the light of the description which follows, and on examining the appended figures, in which:

FIG. 1 is a cross-sectional view of a composite part of the prior art, as described in the preamble of the present description,

FIG. 2 is a perspective view of this same piece,

FIG. 3 is a sectional view of a composite part during manufacture with the process of the present invention,

FIG. 4 is a cross-sectional view of this part once manufactured, and

- Figure 5 is a cross-sectional view of another part manufactured with the method according to the invention. In all of these figures, identical or similar references denote identical or similar members or sets of members.

Referring now to FIG. 3, it can be seen that the preform defined by the stack of folds A and by the two stackings of L, B and C folds has been positioned on a tool of FIG. molding M.

More specifically, the parts of the stack of folds L, B and C, which are substantially perpendicular to the stack of folds A, are placed between the two metal cores M1 and M2 of the molding apparatus M.

Note that the fold plane stack A can be assembled to the two stack of L, B and C folds prior to the introduction of the preform thus formed between the two cores M1 and M2.

According to another possibility, it is possible to start by assembling the two stacks of plies in L, B and C, then to introduce them between the two cores M1 and M2, and finally to cover them with the plane stack A folds.

According to yet another possibility, it is possible to position each of the stack of folds in L, B and C and the plane stack of folds A one after the other, in the molding tool M.

Whatever the assembly sequence adopted, we thus arrive at the configuration shown in FIG. 3, from which fiber loops b are made inside the portions 81 and 82 of the L, B fold plies. and C which are substantially perpendicular to the stack plane A folds.

More precisely, by means of an automatic sewing machine comprising a needle 9, these fibers are brought inside the plane stack of folds A from the free face 11 of the latter, the fiber is penetrated inside the respective part 81, 82 of each stack of folds L, B and C, the loop b is made inside this part, then the fiber is removed by the free face 1 1 of the stacking fold plane A, near the entry point of this fiber in this stack.

The general direction of the fiber, outside the loop B, is substantially perpendicular to the plane stack A, as can be seen in FIG. This operation is repeated as many times as necessary, so as to obtain a plurality of fibers each defining loops b1, b2, b3 formed inside the portions 81 and 82 of the L, B and C stacks. fibers having a general direction substantially perpendicular to the plane stack A.

This method of making loops, allowing a machine to work on only one side of the composite preform, is commonly known as "tufting", meaning in fact "tufting".

Once the establishment of these curly fibers made, we close the molding tool M, and is injected under pressure inside the polymerizable resin, which will then fill all the interstices that are in the preform defined by the stacks of folds A, B, C.

This resin will in particular be positioned around the fibers forming the loops b1, b2, b3.

Once this introduction of resin has been carried out, the molding tool M is subjected to a rise in temperature, allowing the rapid polymerization of this resin.

The fibers forming the loops b1, b2, b3 make it possible to achieve a very strong reinforcement of the junction zone of the three stackings of folds A, B, C.

In particular, these fibers make it possible to obtain excellent tearing resistance of the L, B and C folds with respect to the stack of A folds.

It should be noted further that the possibility of tufting once the preform is on the molding tool M is of great convenience from an industrial point of view, as compared to seaming operations. conventional as shown in Figure 2, requiring the movement of one or more sewing machines on several sides of the preform. Of course, one can choose at will the characteristics of the fibers forming the loops b1, b2, b3, and the shape and spatial distribution of these loops.

For example, these loops can be made with carbon wire, and be spaced at a pitch of 3 mm from each other, penetrating to about fifty millimeters inside the parts 81 and 82 of the Stacking of folds in L, B and C.

By way of examples also, the folds forming the stacks A, B and C may be formed of satin carbon.

The stack A may comprise for example 20 plies, and the stacks B and C 5 folds each.

FIG. 5 shows an embodiment in which the junction between the stackings of folds A, B, C is further reinforced compared with the embodiment of FIG. 4.

In this embodiment, a first group of loops b1, b2, b3 and a second group of loops b4, b5 are provided, the length 11 and the inclination a1 of the first group of loops b1, b2, b3 relative to one another. at the perpendicular direction P to the plane stack A being greater than those 12, a2 of the second group of loops b4, b5.

Of course, the present invention is not limited to the embodiments described and shown, provided by simple examples.

Claims

1. A method of manufacturing a T composite part by resin transfer molding, comprising the steps of:

it is possible to use a substantially flat plane (A) of pleats and with two stacked L (B, C) stacks,

placing said preform so that said L-shaped stacks (B, C) are found between two cores (M1, M2) of a resin transfer molding tool (M), to enter and exit fibers through it planar stack (A) in a direction perpendicular or quasi-perpendicular to this stack (A) and so as to form loops (b1, b2, b3) within the portions (81, 82) of said L-shaped stacks (B C) which are substantially perpendicular to said plane stack,

close the molding tool (M),

injecting resin into the molding tool (M), and heating the molding tool (M) to cure the resin.

2. Method according to claim 1, wherein said plane stack (A) and said L-shaped stacks (B, C) are assembled prior to the introduction of the preform between the two cores (M 1, M2) of the tool. molding (M).

3. Method according to claim 1, wherein said stacks are assembled L (B, C), they are introduced between the two cores (M1, M2) of the molding tool (M), and are covered with said stack plan (A).

4. The method of claim 1, wherein each of said L-shaped stacks (B, C) and said plane stack (A) are positioned one after the other in the molding tool (M).

5. Method according to any one of the preceding claims, in which loops of different lengths (b1, b2, b3 and b4, b5) are formed.

6. Method according to any one of the preceding claims, wherein one forms loops (b1, b3 and b4, b5) slightly inclined (a1 and a2) relative to the perpendicular direction (P) to said stack plane (A).

7. Method according to any one of the preceding claims, wherein one forms a first (b1, b2, b3) and a second (b4, b5) groups of loops, the length and the inclination of said first group of loops (b1). , b2, b3) relative to the perpendicular direction (P) to said plane stack being greater than those of said second group of loops (b4, b5).

A T-component obtained by a process according to any one of the preceding claims.