阅读说明：本技术 吸声面板及其生产方法、***件、飞行器及其发动机短舱 (Sound-absorbing panel, method for producing same, insert, aircraft and nacelle of an aircraft ) 是由 T·里科贝内 H·梅纳 J·拉兰纳 A·波特 于 2019-07-02 设计创作，主要内容包括：一种吸声面板的生产方法,包括：生产步骤,在该步骤期间生产复合结构；提供步骤,在该步骤期间提供插入件,每个插入件包括喷口和盖帽,喷口是具有通孔的中空圆柱体的形式,盖帽包括圆柱体形式的底座和圆锥体形式的覆盖件,底座容纳在孔中；定位步骤,在该步骤期间,插入件通过覆盖件穿入复合结构中而定位在复合结构中,使得孔在复合结构的一侧和另一侧开口；聚合步骤,在该步骤期间,具有插入件的复合结构被聚合；移除步骤,在该步骤期间,移除盖帽；第一组装步骤,在该步骤期间,蜂巢结构固定至聚合复合结构；第二组装步骤,在该步骤期间,后蒙皮固定至蜂巢结构。此方法能够获得具有非常小的直径的孔的吸声面板,确保低频声波的更好衰减。(A method of producing an acoustic panel comprising: a production step during which a composite structure is produced; providing steps during which inserts are provided, each insert comprising a spout in the form of a hollow cylinder with a through hole and a cap comprising a base in the form of a cylinder and a cover in the form of a cone, the base being housed in the hole; a positioning step during which the insert is positioned in the composite structure by the penetration of the covering into the composite structure, so that the holes open on one side and on the other of the composite structure; a polymerization step during which the composite structure with the insert is polymerized; a removal step during which the cap is removed; a first assembly step during which the honeycomb structure is fixed to the polymeric composite structure; a second assembly step during which the rear skin is fixed to the honeycomb structure. This method makes it possible to obtain a sound-absorbing panel with holes of very small diameter, ensuring a better attenuation of the low-frequency sound waves.)

1. A method (40) of producing a sound absorbing panel (20), the method (40) of producing comprising:

-a production step (42) during which a composite structure (22) is produced,

-a providing step (43) during which inserts (28) are provided, and wherein each insert (28) comprises a spout (30) in the form of a hollow cylinder with a through hole (34) and a cap (32) comprising a base (36) in the form of a cylinder and a cover (38) in the form of a cone, and wherein the base (36) is housed in the hole (34),

-a positioning step (44) during which the insert (28) is positioned in the composite structure (22) by the penetration of the covering (38) into the composite structure (22) so that the hole (34) is open on one side and on the other side of the composite structure (22),

-a polymerization step (46) during which the composite structure (22) with the insert (28) is polymerized,

-a removal step (48) during which the cap (32) is removed,

-a first assembly step (50) during which a honeycomb structure (24) is fixed to the polymeric composite structure (22), and

-a second assembly step (52) during which a rear skin (26) is fixed to the honeycomb structure (24).

2. The production method (40) according to claim 1, wherein the providing step (43) is preceded by an overmoulding step during which the spout (30) is overmoulded on the base (36).

3. An insert (28) for implementing a production method (40) according to claim 1 or 2, and comprising: a spout (30) in the form of a hollow cylinder having a through hole (34), and a cap (32) comprising a base (36) in the form of a cylinder and a cover (38) in the form of a cone, and wherein the base (36) is received in the hole (34).

4. An acoustic panel (20) obtained using the production method according to claim 1 or 2.

5. A nacelle (14) for an aircraft engine, comprising at least one sound-absorbing panel (20) according to claim 4.

6. An aircraft (10) comprising at least one nacelle according to claim 5.

Technical Field

The present invention relates to a method for producing a sound-absorbing panel comprising an insert, to a sound-absorbing panel obtained using such a production method, to an aircraft nacelle comprising such a sound-absorbing panel, and to an aircraft comprising at least one such nacelle.

Background

An aircraft propulsion system comprises an engine, in particular a turbojet engine, and a nacelle surrounding the engine. To absorb the noise generated by the engine, the nacelle includes a sound absorbing panel. Each sound absorbing panel comprises a composite structure to which a honeycomb-form structure and a rear skin are successively fixed.

The composite structure is oriented toward the airflow through the nacelle and is perforated to allow sound waves to pass to the honeycomb structure.

While such acoustic panels are entirely satisfactory, the new generation of engines produce lower frequency noise. In order to absorb these frequencies, the diameter of the holes must be reduced. Drilling of the polymerized composite structure by the tool is limited to holes of 1mm diameter and may further result in the severing of the composite fibers of the composite structure.

In order to improve the absorption of these new frequencies, it is desirable to find a method which enables the production of sound-absorbing panels with a new framework, in particular with holes of very small diameter.

Disclosure of Invention

It is an object of the present invention to provide a method of producing a sound-absorbing panel that enables absorption of sound waves having a low frequency.

To this end, a production method of a sound absorption panel is proposed, the production method comprising:

-a production step during which a composite structure is produced,

-a providing step during which inserts are provided, and wherein each insert comprises a spout in the form of a hollow cylinder with a through hole, and a cap comprising a base in the form of a cylinder and a cover in the form of a cone, and wherein the base is housed in the hole,

-a positioning step, during which the insert is positioned in the composite structure by the penetration of the covering into the composite structure, so that the holes open on one side and on the other side of the composite structure,

-a polymerization step during which the composite structure with the insert is polymerized,

-a removal step during which the cap is removed,

-a first assembly step during which a honeycomb structure is fixed to the polymeric composite structure, and

-a second assembly step during which a rear skin is fixed to the honeycomb structure.

This production method makes it possible to obtain a sound-absorbing panel with very small holes, in particular with a diameter of less than 1mm, which ensures a better attenuation of the low-frequency sound waves.

Advantageously, the providing step is preceded by an over-moulding step during which the spout is over-moulded on the base.

The invention also proposes an insert for implementing the production method according to one of the above variants and comprising: a spout in the form of a hollow cylinder having a through hole and a cap comprising a base in the form of a cylinder and a cover in the form of a cone, and wherein the base is received in the hole.

The invention also proposes a sound-absorbing panel obtained using the production method according to one of the preceding embodiments.

The invention also proposes a nacelle for an engine comprising at least one sound-absorbing panel according to the previous variant.

The invention also proposes an aircraft comprising at least one nacelle according to the previous variant.

Drawings

The above features and other features of the present invention will be more clearly understood from a reading of the following description of embodiments, given with reference to the accompanying drawings, in which:

figure 1 is a side view of an aircraft according to the invention,

figure 2 is a side cross-sectional view of a sound absorbing panel according to the present invention,

FIG. 3 shows the front insert placed in the composite structure, and

fig. 4 shows an algorithm of a method of producing a sound absorption panel according to the present invention.

Detailed Description

Fig. 1 shows an aircraft 10 comprising at least one propulsion system 12 comprising an engine (in particular a dual flow turbojet) and a nacelle 14 surrounding the engine.

The nacelle 14 is integrated with sound absorbing panels arranged around the airflow flowing through the nacelle 14.

Fig. 2 shows the structure of the sound absorption panel 20.

The sound absorbing panel 20 includes a composite structure 22 positioned against the airflow 50, a honeycomb structure 24 secured to the composite structure 22, and a rear skin 26 secured to the honeycomb structure 24.

The fixing of the honeycomb structure 24 and the rear skin 26 is performed by adhesive bonding.

Fig. 3 shows an insert 28 that includes a spout 30 and a cap 32. The spout 30 is in the form of a hollow cylinder having a through hole 34. The cap 32 includes a base 36 in the form of a cylinder and a cover 38 in the form of a cone. The diameter of the base 36 is adapted to the diameter of the hole 34 in order to enable insertion and removal of the base 36 into and from the hole 34.

The holes 34 may in particular have a small diameter, in particular less than 1 mm.

The composite structure 22 includes jets 30, and each jet 30 is embedded in the composite structure 22 such that the holes 34 open on one side and the other side of the composite structure 22. Accordingly, the length of the spout 30 is at least equal to the thickness of the composite structure 22.

During production of the composite structure 22, the insert 28 is integrated in the composite structure 22 and then the cap 32 is extracted so as to leave only the spout 30 and therefore the release hole 34. The positioning of the insert 28 is performed by passing the cover 38 into the composite structure 22 until the cap 32 is exposed from the composite structure 22 and the holes 34 open on one side and the other side of the composite structure 22. Removal of the cap 32 is performed, for example, by applying a lateral force, which enables the cap 32 to be removed from the spout 30.

Fig. 4 shows a method 40 for producing the sound absorption panel 20. The production method 40 comprises:

a production step 42 during which the composite structure 22 is produced,

a providing step 43, during which the inserts 28 are provided, and in which each insert 28 comprises a spout 30 in the form of a hollow cylinder with a through hole 34, and a cap 32 comprising a base 36 in the form of a cylinder and a cover 38 in the form of a cone, and in which the base 36 is housed in the hole 34,

a positioning step 44 during which the insert 28 is positioned in the composite structure 22 by passing the covering 38 (i.e. the cone) into the composite structure 22,

a polymerization step 46 during which the composite structure 22 with the insert 28 is polymerized,

a removal step 48, during which the cap 32 is removed,

a first assembly step 50 during which the honeycomb structure 24 is fixed to the polymerized composite structure 22, and

a second assembly step 52, during which the rear skin 26 is fixed to the honeycomb structure 24.

The positioning of the inserts 28 prior to polymerization prevents the uncured composite fibers of the composite structure 22 from breaking.

Each insert 28 is positioned manually or using a suitable tool, for example of the gun type. The conical shape of the overlay 38 facilitates penetration of the insert 28 into the composite structure 22.

The presence of the cap 32 prior to polymerization prevents the pores 34 from being blocked by the resin of the composite structure 22 during polymerization.

To ensure that spout 30 is better retained in composite structure 22 and to reduce the risk of resin migration of composite structure 22, spout 30 includes a widened base 39.

If the spout 30 and the cap 32 are produced independently of each other, insertion of the base 36 into the aperture 34 may be performed manually. However, the spout 30 is preferably produced by over-molding onto the base 36.