FR3128659A1 - DEVICE AND METHOD FOR REMOVING A METAL ALLOY CORE IN A PART MADE OF COMPOSITE MATERIAL. - Google Patents

Abstract

The process for eliminating a metal alloy core (3) in a composite material part (2) comprising a structure based on fibers embedded in a polymer matrix comprises the following succession of steps, a step of heating an oil bath (5) contained in a container (4), at a temperature above a melting temperature of the alloy, a step of complete immersion and displacement of the part (2) in the bath of oil (5), and a step of extracting the part (2) from the oil bath (5) after melting and removal of the core (3). Figure for abstract: Figure 2

Description

DEVICE AND METHOD FOR THE ELIMINATION OF A METAL ALLOY CORE IN A PART MADE OF COMPOSITE MATERIAL.

Technical field of the invention

The present invention relates to a process for eliminating a metal alloy core in a part made of composite material. The present invention also relates to a device for eliminating the metal alloy core in the composite material part.

Technical background

The use of composite materials is particularly advantageous in the aeronautical industry because these materials are relatively light and have good mechanical properties.

A composite material conventionally used for aeronautics comprises a fibrous preform embedded in a polymeric resin. The preform can come from a three-dimensional weaving or can be obtained by draping and superimposing several fabrics.

The resin (or matrix) can be injected into the preform or else the preform can be impregnated beforehand with the resin.

The shaping of the final part is generally carried out using tools comprising a mould. In the case where a resin must be injected into a preform, the preform is placed in the cavity of a mold and the mold is covered with a counter-mold. The tooling includes a port for injecting resin into the mold cavity as well as a port for vacuuming the mold cavity.

In the case where the preform is already impregnated with the resin, the preform is placed in the cavity of a mold which can be covered with a flexible tarpaulin or a counter-mold.

However, some composite material parts have complex geometries that cannot be obtained by molding. In this case, it is known to form the part in composite material around a core in eutectic metal alloy. The eutectic core is then removed from the composite material part by placing the assembly in an oven and increasing the temperature beyond the melting point of the eutectic core in order to melt it. Melting is generally carried out by gas convection, by conduction or even by induction. This type of process requires fairly long exposure times for the core and the composite material part (about fifteen hours at a temperature 25° Celsius above the melting temperature). However, too high a temperature or a prolonged exposure time risks damaging the part by causing a deterioration in its mechanical properties.

Moreover, once the eutectic core has melted, residues of the materials forming the alloy can be found on the surfaces of the composite material part, which implies an additional step of cleaning these surfaces.

In addition, during melting by gas convection, conduction or induction, the temperature gradient that the core undergoes leads to a phase separation of the metal alloy as well as to oxidation phenomena of the materials composing it. This has the effect of increasing the melting temperature of the metal alloy. It then becomes more difficult to reuse these cores.

The current methods are therefore not entirely satisfactory.

The object of the present invention is to overcome these drawbacks by eliminating the cores of the parts made of composite material by liquid convection.

The present invention relates to a process for eliminating a metal alloy core in a part made of composite material comprising a structure based on fibers embedded in a polymer matrix.

According to the invention, said elimination process comprises the following succession of steps:
- a step of heating an oil bath contained in a container, to a temperature above a melting temperature of the alloy,
- a step of complete immersion and displacement of the part in the oil bath, and
- a step of extracting the part from the oil bath after melting and elimination of the core.

Thus, thanks to the invention, the elimination of the nuclei is carried out by liquid convection, which maximizes the convection coefficient. In addition, the movement of the part in the oil bath generates liquid flows which pass through areas of the part where the core is inserted. Thus, all the residues of the fusion of the core which could have remained on the surface of the part are removed.

The elimination process according to the invention may comprise one or more of the following characteristics or steps, taken separately from each other, or in combination with each other:
- during the immersion and movement step, the part is carried and moved by a support element which moves along at least one guide,
- said support element is a carriage and said at least one guide is at least one rail on which said carriage moves,
- during the immersion and displacement step, the part is subjected to at least one rotational movement,
- the temperature of the oil is greater than or equal to the crosslinking or curing temperature of said polymer matrix, the latter being for example 180° C.,
-- the temperature of the oil is higher than the melting temperature of the eutectic,

-- for a eutectic which melts at 195°C, the temperature of the oil can be between 200 and 210°C, and
-- the oil is mineral or synthetic.

The present invention also relates to a disposal device for implementing a method as described above, in which it comprises:
- a container containing an oil bath, this oil having a temperature higher than a melting temperature of the metal alloy core intended to be melted,
- at least one guide, and
- a support element configured to support the part made of composite material, this support element being capable of being moved on said at least one guide into the oil bath, with a view to immersing said part, and up to outside the oil bath in view of extracting the part.

The device according to the invention may comprise one or more of the following characteristics, taken separately from each other, or in combination with each other:
- said at least one guide comprises at least one rail and preferably two parallel rails, and said at least one support element is a carriage movable on this or these rails,
- said at least one guide comprises a first part located at the inlet of the oil bath, a second part located at the bottom of the oil bath and a third part located at the outlet of the oil bath,
- the support element also comprises a holding element configured to hold the part on the support element during its movement in the oil bath, and
- the support element is configured to perform at least one rotational movement of the part inside the oil bath.

Brief description of figures

Other characteristics and advantages of the invention will appear during the reading of the detailed description which will follow for the understanding of which reference will be made to the appended drawings in which:

There illustrates a schematic perspective view of a disposal device according to one embodiment of the invention;

There shows a schematic perspective view of a support element of the disposal device according to one embodiment of the invention;

There shows a schematic perspective view of a support element in a container of the disposal device according to one embodiment of the invention; And

There schematically illustrates the main steps of a process for eliminating a core in a part made of composite material according to one embodiment of the invention.

Claims (10)

Process for removing a metal alloy core (3) from a composite material part (2) comprising a structure based on fibers embedded in a polymer matrix, characterized in that said process comprises the following succession of steps:
- a heating step (E1) of an oil bath (5) contained in a container (4), to a temperature higher than a melting temperature of the alloy,
- a step (E2) of complete immersion and displacement of the part (2) in the oil bath (5), and
- a step (E3) of extracting the part (2) from the oil bath (5) after melting and removal of the core (3). Removal process according to Claim 1, characterized in that, during the step (E2) of immersion and displacement, the part (2) is carried and displaced by a support element (10) which moves along at least one guide (6). Disposal method according to claim 2, characterized in that said support element (10) is a carriage and said at least one guide (6) is at least one rail (6) on which said carriage moves. Removal process according to any one of the preceding claims, characterized in that, during the step (E2) of immersion and displacement, the part (2) is subjected to at least one rotational movement. Removal process according to any one of the preceding claims, characterized in that the temperature of the oil is greater than or equal to the crosslinking temperature of the said polymer matrix of the part (2). Elimination device for implementing a method according to one of the preceding claims, said device (1) being characterized in that it comprises:
- a container (4) containing an oil bath (5), this oil having a temperature higher than a melting temperature of the metal alloy core (3) intended to be melted,
- at least one guide (6), and
- a support element (10) configured to support the part (2) made of composite material, this support element (10) being adapted to be moved on said at least one guide (6) into the oil bath (5 ), for the immersion of said part (2), and to the outside of the oil bath (5) for the extraction of the part (2). Disposal device according to Claim 6, characterized in that the said at least one guide (6) comprises at least one rail (6) and preferably two parallel rails (6A, 6B), and the said at least one support element ( 10) is a mobile carriage on this or these rails (6, 6A, 6B). Elimination device according to either of Claims 6 and 7, characterized in that the said at least one guide (6) comprises a first part (7A, 7B) located at the inlet of the oil bath (5), a second part (8A, 8B) located at the bottom (4A) of the oil bath (5), and a third part (9A, 9B) located at the outlet of the oil bath (5). Disposal device according to any one of Claims 6 to 8, characterized in that the support element (10) also comprises a holding element configured to hold the part (2) on the support element (10) during its movement in the oil bath (5). Elimination device according to any one of Claims 6 to 9, characterized in that the support element (10) is configured to carry out at least one rotational movement of the part (2) inside the bath of oil (5).