WO2009030682A1

WO2009030682A1 - Method and device for analysing processes for producing parts of composite materials by infusion or injection and for characterising said composite materials

Info

Publication number: WO2009030682A1
Application number: PCT/EP2008/061558
Authority: WO
Inventors: Sylvain Chatel
Original assignee: European Aeronautic Defence And Space Company - Eads France
Priority date: 2007-09-05
Filing date: 2008-09-02
Publication date: 2009-03-12
Also published as: FR2920336A1; FR2920336B1

Abstract

The invention relates to a method and a device for analysing processes for producing parts of composite materials by infusion or injection, and for characterising said composite materials. The composite material(s) include at least one matrix (4) and a reinforcement (6) imbedded in the matrix, wherein the reinforcement is placed on the surface (16) of a tool (8), the reinforcement is covered with a flexible membrane (24) or a plurality of flexible membranes which are then sealed against the surface of the tool, and a fluid for forming the matrix is introduced into the space defined by the tool and the flexible membrane closest to the tool. According to the invention, the method comprises measuring the altitude in a whole area (28) or a plurality of areas of the flexible membrane (24) or of the membrane in the plurality of flexible membranes that is the most remote from the tool (8) based on time.

Description

METHOD AND DEVICE FOR ANALYZING PROCESSES FOR PRODUCING PARTS IN COMPOSITE MATERIALS, BY INFUSION OR INJECTION, AND CHARACTERIZATION THEREOF

COMPOSITE MATERIALS

DESCRIPTION

TECHNICAL AREA

The present invention relates to a method for analyzing processes for manufacturing composite material parts, by infusion or injection, and to characterize the composite materials that are formed during the manufacture of parts.

It also relates to a device for the implementation of this method.

It is important to understand the physical phenomena that occur during such a process, to analyze this process to control the parameters that govern it and to study the behavior of the composite material during the various stages of its manufacture. as well as the characteristics of this material.

These studies allow

to optimize the process, that is to say to choose the parameters of this process according to the quality desired for the parts manufactured by the process, and

to know the properties of the material constituting the manufactured parts. We are then able to

- master the evolution of the family of processes, - master the application of such processes to other families of parts, composed of other materials and / or other geometries, and reduce the costs and development time of the manufacturing ranges.

STATE OF THE PRIOR ART

So far, nothing has been done in this area. At most, the temperature of the fluid intended to form the composite material has been measured.

STATEMENT OF THE INVENTION

The present invention aims to fill this gap.

Admittedly, US 2002/020934 A discloses a method of manufacturing parts made of composite material; but only a pressure and temperature control is envisaged in this document. EP 1 555 104 A also discloses processes for manufacturing composite material parts. In this document, it is a question of measuring the thickness of the molded material of the reinforcing substrate, by means of a dial gauge (in English, dial gauge) during the evacuation of the resin. But such a measurement is made using a point sensor and does not allow to study the flatness of a zone or to highlight any areas of defects. The present invention overcomes this disadvantage by performing an altitude measurement in the whole of an area (or a plurality of areas) and therefore in an infinite number of points. a method for analyzing a process for manufacturing parts in at least one composite material, by infusion or injection, and for characterizing the composite material, this composite material comprising at least one matrix and a reinforcement embedded in the matrix, in which process:

the reinforcement is placed on the surface of a tool,

the reinforcement is covered by a flexible membrane or a plurality of flexible membranes,

this flexible membrane or this plurality of flexible membranes is sealed against the surface of the tool, and

a fluid intended to form the matrix is introduced into the space delimited by the tool and the flexible membrane or that of the plurality of flexible membranes which is closest to the tool, this method being characterized by the fact that the an altitude measurement is made throughout an area, or a plurality of areas, of the flexible membrane or that of the plurality of flexible membranes that is farthest from the tool, based on of time, the altitude being thus measured in an infinite number of points. To do this, the altitude is preferably measured by means of an optical sensor, for example a camera.

In this case, according to a preferred embodiment of the invention, the area is illuminated by means of a structured light source and the optical sensor comprises a camera which observes the area thus illuminated.

In the present invention, the altitude is preferably furthermore measured at at least one point of the flexible membrane or that of the plurality of flexible membranes which is furthest from the tool, as a function of time, at means of at least one touch sensor. In the invention, the altitude can be measured during the induction of the fluid or before this introduction of the fluid.

In the present invention, the pressure prevailing in the space delimited by the tool and the flexible membrane or that of a plurality of flexible membranes which is closest to the tool are also preferably measured as a function of time. .

Preferably, the propagation of the fluid in the space delimited by the tool and the flexible membrane or that of the plurality of flexible membranes which is closest to the tool is also measured.

The temperature is also preferably measured at at least one point of the composite material.

It is also possible to measure the temperature in at least one point of the external face of the flexible membrane or that of the plurality of flexible membranes that is furthest from the tool, as a function of time.

It is also possible to measure the temperature in at least one point of the tool. According to a particular embodiment of the invention, the tool provided with the flexible membrane or the plurality of flexible membranes is placed in an enclosure and the temperature prevailing in this chamber is further measured. According to another particular embodiment, at least one fluid inlet duct is provided in the space delimited by the tool and the flexible membrane or that of the plurality of flexible membranes that is closest to the tool, and the temperature of the fluid in this conduit is further measured.

The present invention also relates to a device for analyzing a method of manufacturing parts in at least one composite material, by infusion or injection, and to characterize the composite material, this composite material comprising at least one matrix and a reinforcement embedded in the matrix, process in which

the reinforcement is placed on the surface of a tool,

this flexible membrane or this plurality of flexible membranes is sealed against the surface of the tool, and a fluid intended to form the matrix is introduced into the space delimited by the tool and the flexible membrane or that of the plurality of flexible membranes that is closest to the tool, this device being characterized in that comprises at least one altitude measuring member in the whole of an area, or a plurality of zones, of the flexible membrane or that of the plurality of flexible membranes which is furthest from the tool, according to the time.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood on reading the description of exemplary embodiments given below, purely by way of indication and in no way limiting, with reference to the single appended figure, which is a diagrammatic sectional view of an installation. making it possible to manufacture composite material parts by membrane infusion, this installation being provided with various sensors making it possible to implement a method according to the invention.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

In the example shown in this figure, we therefore see an installation for implementing a method of manufacturing composite material parts, such as part 2.

In this example, it is a membrane infusion process and the composite material comprises an organic matrix 4 and a reinforcement 6 which is embedded in this matrix. This reinforcement 6 is for example made of carbon fibers, glass or Kevlar (trademark).

The installation comprises a tool or tool 8 and an enclosure 10 forming an oven and containing the tool 8. In this enclosure, there are provided thermal regulation members of the enclosure, which are symbolized by the block 12.

The installation also comprises at least one conduit 14 for supplying a resin intended to form the matrix. One end of this conduit opens at the surface 16 of the tool, on which the reinforcement 6 is intended to rest, while the other end of the conduit 14 is connected to means (not shown) for supplying resin .

In addition, the installation comprises another conduit 18, one end of which opens out at this surface 16 and the other end of which is connected to a vacuum draw means 20. In the example, to manufacture the piece 2 of material composite, the reinforcement 6 is placed on the surface 16 of the tool 8; a resin drain 22 is however provided between the surface and the reinforcement in this example. The reinforcement is then covered by a flexible membrane 24, so that the conduits 14 and 18 end in the space defined by this flexible membrane and the tool; and this flexible membrane is sealed against the surface of the tool by means of a sealing member 26. Next, the space mentioned above is evacuated by the drawing means 20, so that the resin is attracted to this space and fills it; then the temperature is raised in the chamber - for this purpose, the thermal regulating members 12 comprise for example a heating resistor - and this temperature is regulated until the resin is polymerized.

In the example, to implement the present invention, the altitude of an area 28 or a plurality of zones of the flexible membrane 24 is measured as a function of time. The zone 28 is, as can be seen, above the reinforcement 6 and the altitude is measured relative to the surface of the tool 8. For this measurement, an optical sensor comprising a camera 30 which observes the zone 28. This camera is associated with a structured light source 32 with which area 28 is illuminated. In addition, the camera 30 is provided with a system 34 for processing the signals supplied by this camera in order to determine the altitude of the zone 28. It is specified that the enclosure 10 has a window 36 facing the area 28 and allowing the passage of structured light and the observation of the area by the camera.

The projection of structured light on the studied area 28 generates mobile fringes that are observed thanks to the camera and which make it possible to determine the altitude by triangulation in a known manner.

In the example shown, the altitude of the flexible membrane is measured at one or more points thereof, such as points A, B, according to the time. To do this, one or more tactile sensors 38, 40 are used. As can be seen in the figure, these tactile sensors are mounted on a support 42 whose part situated above the studied zone 28 is of course transparent.

The altitude of the zone 28 and the points A and B thereof can be measured during the introduction of the resin into the space defined by the tool and the membrane and before this introduction, that is to say say during the application of emptiness.

The altitude measurement over the whole of the zone 28 thanks to the camera (or any other equivalent optical sensor) makes it possible to study the flatness of this zone and to highlight possible zones of defects, something that the we could not do with point sensors.

The use of tactile sensors makes it possible to confirm the optical measurements made with the camera. It should be noted that these touch sensors allow continuous measurement over time while the camera only allows discontinuous measurements as a function of time.

In addition, the altitude measurement before the introduction of the fluid constituted by the resin in the space defined by the tool and the flexible membrane makes it possible to know how the reinforcement 6 behaves before this introduction.

This reinforcement is generally made of fibers. However, in some processes, these fibers are bonded by means of a suitable binder: the latter is put in place, the space in the space mentioned above is evacuated. top and heat until the fibers are bound. The described installation makes it possible to do all this and the measuring means mentioned above make it possible to see how the material behaves before the introduction of the resin.

Altitude measurements as a function of time make it possible to know the thickness of the part 2 at various points thereof during the various stages of its manufacture. In the example of the method according to the invention, the pressure prevailing in the space mentioned above is also measured as a function of time. To do this, at least one vacuum sensor 44 is used which communicates with this space via a duct 46; the latter opens at the surface of the tool, as seen in the figure.

We can also measure the propagation of the resin in this space. To do this, the chamber 10 is provided with another window 48, below the tool 8 which supports the reinforcement 6, as seen in the figure, and optical measurements are made through this window for example using a camera 50.

In this case, a transparent tool 8 is used to support the reinforcement 6 and a transparent conduit 14 for bringing the resin into the space mentioned above.

In the example of the method according to the invention, the temperature is also measured at one or more points of the composite material that is formed. To do this, one or more sensors of Such sensors are connected to a system 54 for processing the signals they provide to determine each measured temperature, as seen in the figure. According to the invention, it is also possible to measure

the temperature in at least one point C of the external face of the flexible membrane, face opposite to that which is in contact with the reinforcement 6, and / or the temperature in at least one point

D of the surface 16 of the tool, and / or the temperature in the enclosure 10,

and / or the temperature of the resin in the conduit 14.

For this purpose, temperature sensors (not shown) are provided at point C and / or at the point

D and / or in the enclosure and / or in the conduit 14 and is connected to a signal processing system they provide to determine each temperature. The system 54 mentioned above can be provided for this purpose.

All the measurements made, mentioned above, make it possible in particular to know and modify the parameters of the process for manufacturing the composite material in question, in real time or a posteriori.

They also make it possible to understand the physical phenomena that take place during manufacture and also to know the properties of the composite material, that is to say, to characterize this material. composite material, and to modify its properties, in order to optimize the manufacturing process as well as the composite material.

It should be noted that instead of placing the vacuum through the tool 8, it can be done through the membrane 24.

In addition, the matrix is not necessarily organic: it can be for example metallic. The manufacturing process is then adapted to the type of matrix used. In particular, the membrane is adapted.

In addition, evacuation is not essential in the present invention; in other examples, there is no vacuum: there is air between the flexible membrane and the tool. So, this flexible membrane does not need to be waterproof.

This is for example the case when the fluid used to form the matrix is a hot metal, which leads to a metal matrix, or even when the fluid is an epoxy resin (liquid), which leads to an organic matrix.

In this case, in order to manufacture the composite material, the fluid intended to form the matrix is injected between the flexible membrane and the tool, for example by means of a piston or a jack.

In addition, the present invention also applies to the case where the same part comprises more than one composite material. This piece is then made from more than one reinforcement and / or more than one die. The altitude of an area (or zone plutality) of the flexible membrane is still measured (relative to to the tool), which still allows to know the thickness of what covers the membrane in this area.

In addition, the invention does not apply only to processes using a single flexible membrane: it also applies to processes that use more than one. So, one of the flexible membranes is the closest to the tool and another is the furthest away from this tool. The fluid intended to form the matrix is then sent between the tool and the membrane closest to it.

In this case, an altitude measurement is carried out in the whole of an area (or a plurality of zones) of the flexible membrane furthest from the tool.

It is also possible to measure the pressure in the space between the tool and the membrane closest to the latter and / or the temperature in at least one point of the membrane which is the furthest away from it. In addition, it is still possible to study the propagation of fluid in the space mentioned above.

Claims

1. Method for analyzing a process for manufacturing parts (2) in at least one composite material, by infusion or injection, and for characterizing the composite material, this composite material comprising at least one matrix (4) and a reinforcement (6) embedded in the matrix, wherein

the reinforcement is placed on the surface (16) of a tool (8),

the reinforcement is covered by a flexible membrane (24) or a plurality of flexible membranes,

a fluid intended to form the matrix is introduced into the space delimited by the tool and the flexible membrane or that of the plurality of flexible membranes which is closest to the tool, this method being characterized by the fact that the an altitude measurement is made in the whole of an area (28), or a plurality of zones, of the flexible membrane (24) or that of the plurality of flexible membranes which is furthest from the tool (8), as a function of time, the altitude being thus measured in an infinite number of points.

The method of claim 1, wherein the altitude is measured by means of an optical sensor (30).

The method of claim 2, wherein the area is illuminated by a structured light source (32) and the optical sensor comprises a camera (30) which observes the illuminated area.

4. Method according to any one of claims 1 to 3, wherein the altitude is further measured in at least one point (A, B) of the flexible membrane (24) or that of the plurality of flexible membranes which is the furthest away from the tool, as a function of time, by means of at least one touch sensor (38, 40).

5. Method according to any one of claims 1 to 4, wherein the altitude is measured during the indroduction of the fluid.

6. Method according to any one of claims 1 to 4, wherein the altitude is measured before the introduction of the fluid.

7. Method according to any one of claims 1 to 6, wherein the pressure prevailing in the space delimited by the tool (8) and the flexible membrane (24) or that of a plurality of flexible membranes which is closest to the tool, as a function of time.

The method according to any one of claims 1 to 7, wherein the propagation of the fluid in the space delimited by the tool (8) and the flexible membrane (24) or that of the plurality of flexible membranes that is closest to the tool.

The method of any of claims 1 to 8, wherein the temperature is further measured at at least one point of the composite material.

10. The method of claim 9, wherein the temperature is further measured in at least one point (C) of the outer face of the flexible membrane.

(24) or that of the plurality of flexible membranes that is furthest from the tool, as a function of time.

11. Method according to any one of claims 9 and 10, wherein the temperature is further measured in at least one point (D) of the tool (8).

12. Method according to any one of claims 9 to 11, wherein the tool provided with the flexible membrane or the plurality of flexible membranes is placed in an enclosure (10) and the temperature prevailing in this enclosure.

13. Method according to any one of claims 9 to 12, wherein there is provided at least one conduit (14) of fluid inlet in the space defined by the tool (8) and the flexible membrane (24) or that of the plurality of flexible membranes which is closest to the tool, and the temperature of the fluid in this conduit is also measured.

14. Apparatus for analyzing a process for manufacturing parts (2) in at least one composite material, by infusion or injection, and for characterizing the composite material, this composite material comprising at least one matrix (4) and a reinforcement (6) embedded in the matrix, wherein

the reinforcement is placed on the surface (16) of a tool (8),

the reinforcement is covered by a flexible membrane (24) or a plurality of flexible membranes, this flexible membrane or this plurality of flexible membranes is sealed against the surface of the tool, and

a fluid intended to form the matrix is introduced into the space delimited by the tool and the flexible membrane or that of the plurality of flexible membranes that is closest to the tool, this device being characterized in that comprises at least one elevation measuring member (30) in the whole of an area (28), or a plurality of areas, of the flexible membrane or that of the plurality of flexible membranes which is the most away from the tool, as a function of time.