MOLD INCLUDING A POSITIONING DEVICE AND POSITIONING METHOD

Abstract

MOLD COMPRISING A POSITIONING DEVICE AND POSITIONING METHOD The mold (1) according to the invention comprises a hollow zone (10a) with a peripheral edge (100) for producing a part, characterized in that it comprises a holding device (3) for a preform (2) in the hollow zone (10a), said holding device (3) being fixed to the peripheral edge (100) and extending into the hollow zone (10a) of the mold (1). Since the holding device is integral with the mold, the preform is held in place when the mold is closed during resin injection, thus enabling the production of a good part. Clamping the perimeter of the preform minimizes unwanted movement during tooling closure. The holding device is fixed to the periphery of the mold, preferably with a clamping means to compress the preform. Figure to be published with the abbreviation: Figure 1

Description

Title of the invention: MOLD COMPRISING A POSITIONING DEVICE AND POSITIONING METHOD TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of molds for producing composite parts comprising a preform, for example with a fabric or fibers, and a method for manufacturing said parts. These parts may in particular be used in aeronautics. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Currently the production of certain composite parts is carried out in molds in which a preform is placed.

[0003] These preforms are formed from cut textiles which are positioned by a laser relative to markers (for example glass tracers) in order to make them coincide with the defined theoretical geometry. This positioning guarantees the conformity of the final part.

[0004] The preform, once positioned and dried, is transferred into a mold to provide it with a certain rigidity. The positioning can also be controlled by laser. However, when the mold is closed, there is no longer any view of the preform or the mold geometry. Due to the presence of expansion of the preform, it is not possible to guarantee that it will not move during the injection of the resin or to predict any misalignment of the latter. In fact, dried or compacted preforms are not 100% so, and on the other hand, only certain areas are compacted: it is these excess thicknesses that can generate misalignments during the mold.

[0005] In the event of excessive movement of the preform, in relation to the positioning tolerances of the tracers or non-compliant fiber volume rate, in the event of strong degression, a resin-rich or fiber-rich zone, or even a dry zone, is obtained. The part thus injected will be non-compliant and rejected. Summary of the invention

[0006] The invention offers a solution to the problems mentioned above, by making it possible to avoid any movement of the preform in the mold.

[0007] The mold according to the invention comprises a hollow zone with a peripheral edge for producing a part, it is characterized in that it comprises a device for holding a preform in the hollow zone, said holding device being fixed to the peripheral edge and protruding into the hollow zone of the mold. The holding device being integral with the mold, the preform is held in place when the mold is closed during resin injection, thus allowing the production of a good part. Clamping the perimeter of the preform minimizes unwanted movement when closing the tool. The holding device is fixed to the periphery of the mold, preferably with a clamping means in order to compress the preform.

[0008] According to a first variant, the holding device comprises flanges arranged on the periphery. The flanges will be placed in the most heavily stressed areas.

[0009] Advantageously, the number of flanges is greater than four. The flanges are preferably placed at the four corners of the part. If there are more than four, their positions are based on the geometry of the preform, which allows for more modularity. For example, there will be between 6 and 8 flanges for the manufacture of a fan blade.

[0010] According to a second variant, the holding device is continuous over the entire periphery. The preform is thus held over its entire periphery.

[0011] Advantageously, the holding device comprises openings intended to allow a resin to pass into the mold. For better distribution of the resin on the periphery of the preform, the holding device incorporates openings, such as for example grooves formed in the peripheral frame and constituting empty spaces between the part and the edge so as to create preferential paths for the passage of the resin.

[0012] The invention also relates to a method for producing a part in a mold with one of the preceding characteristics, it is characterized in that it comprises the following steps: • positioning of a preform in the mold, • fixing by the device for holding the positioned preform, • injection of the resin into the mold.

[0013] Advantageously, the positioning is done by a laser. The positioning is thus more precise.

[0014] Advantageously, the preform is fixed by compression of the holding device. The holding device is screwed onto the periphery of the mold, allowing it to be tightened, which will compress the preform.

[0015] Advantageously, the preform is completely dried and compacted before positioning in the mold.

[0016] Advantageously, the preform is partially dried and compacted before positioning in the mold. Since compaction is manual, it requires a lot of effort. This is why it is only carried out on a part of the part, preferably the foot at approximately 110%. BRIEF DESCRIPTION OF THE FIGURES

[0017] The figures are presented for information purposes only and in no way limit the invention.

[0018] [Fig.l] is a section of a mold according to the invention in the open position;

[0019] [Fig.2] is a section of a mold according to the invention in the closed position;

[0020] [Fig.3] is a top view of a first embodiment;

[0021] [Fig.4] is a top view of a second embodiment. DETAILED DESCRIPTION

[0022] The figures are presented as examples to illustrate the invention.

[0023] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0024] Throughout the description, the upper part of figures 1 and 2 will be referred to as "top", and the lower part of said figures will be referred to as "bottom".

[0025] We can see [Fig.l] and 2, a mold 1 in two parts: a lower part 1a and an upper part 1b. The lower part 1a, according to the invention, comprises a hollow zone 10a of one half of the shape of the part to be produced. The upper part 1b has a projecting zone 10b, of another half of the shape of the part to be produced. The shapes of the mold may be different depending on the part to be produced. A seal 11 is placed on the periphery of the hollow zone 10a in order to close the mold in a watertight manner.

[0026] The preform 2 is placed in the hollow area 10a and positioned for example by lasers. A holding device 3 is fixed on the periphery 100 of the hollow area 10a by screws 4 and extends beyond to reach the perimeter of the preform 2.

[0027] In a first embodiment, illustrated [Fig. 3], the holding device 3 consists of flanges 30 distributed over the periphery 100 and screwed. The device may also include visual decoders 32 and laser tracers 33. The decoders 32 make it possible to correctly position the part even in the absence of a laser.

[0028] In a second embodiment, visible in [Fig.4], the holding device 3 consists of a frame 31 of the shape of the periphery 100 and screwed onto the mold 1.

[0029] We will now describe the manufacture of the composite part. Once the preform 2 is ready, that is to say dried and compacted in order to give it a certain rigidity, it is placed in the mold 1 and positioned. This positioning can be done using lasers in order to have a very precise positioning by the laser tracers 33 or by the visual deceptive devices 32. The holding device 3 is placed on the perimeter of the preform and tightened on it by screwing the screws 4. The mold is closed by the installation of the upper part 1b which presses on the seal 11 in order to seal the mold 1. The mold may possibly be placed under vacuum in order to facilitate the migration of the resin. The resin is then injected to finalize the part without the preform is not moved.

[0030] The part thus produced could, for example, be a blade with a thin edge, a vane or a casing.

Claims

Claims

1. Mold (1) comprising a hollow zone (10a) with a peripheral edge (100) for producing a part, comprising a holding device (3, 30, 31) for holding a preform (2) in the hollow zone (10a), said holding device (3) being fixed on the peripheral edge (100) and protruding into the hollow zone (10a) of the mold (1), characterized in that the holding device (3, 30, 31) comprises openings intended to allow a resin to pass into the mold (1).

2. Mold (1) according to claim 1, characterized in that the holding device (3) comprises flanges (30) arranged on the periphery (100).

3. Mold (1) according to the preceding claim, characterized in that the number of flanges (30) is greater than four.

4. Mold (1) according to claim 1, characterized in that the holding device (31) is continuous over the entire periphery.

5. Method for producing a part in a mold (1) according to one of the preceding claims, characterized in that it comprises the following steps: - positioning of a preform (2) in the mold (1), - fixing by the holding device (3, 30, 31) of the positioned preform (2), - injection of the resin into the mold (1) through the openings of the holding device.

6. Method according to the preceding claim, characterized in that the positioning is done by a laser.

7. Method according to one of claims 5 or 6, characterized in that the fixing of the preform (2) is done by compression of the holding device (3, 30, 31).

8. Method according to one of claims 5 to 7, characterized in that the preform (2) is completely dried and compacted before positioning in the mold (1).

9. Method according to one of claims 5 to 7, characterized in that the preform (2) is partially dried and compacted before positioning in the mold (1).

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