WO2013093369A1

WO2013093369A1 - Improved method for pultrusion by vibration and device for implementing the method

Info

Publication number: WO2013093369A1
Application number: PCT/FR2012/053045
Authority: WO
Inventors: Kévin PITIE; José PORTOLES; Noël CARRERE; Frédéric LOUART
Original assignee: Epsilon Composite
Priority date: 2011-12-22
Filing date: 2012-12-21
Publication date: 2013-06-27
Also published as: FR2984796A1

Abstract

The invention relates to a method for manufacturing a part made of a composite material by pultrusion, the method consisting of manufacturing a continuous profile section (P) made of a composite material from a reinforcement (R) impregnated with a matrix and pulled through a die (10), which gradually shapes the composite material into the cross-section of the profile section (P) to be manufactured, the manufacturing method including at least three consecutive steps performed in the die (10): a first step of starting to shape the composite material, an intermediate step of starting to harden the matrix, and a final step of finishing the hardening of the matrix and finishing the shaping of the composite material, the manufacturing method being characterised in that vibrations are applied to the die during the first and/or final step, and in that no vibrations are applied to the die during the intermediate step. The invention also relates to a die for implementing said method, to a pultrusion manufacturing line including said die, and to a part made of a composite material obtained by said method.

Description

IMPROVED VIBRATION PULTRUSION PROCESS AND DEVICE

IMPLEMENTATION

The present invention relates to the use of vibrations in a pultrusion process.

In various processes and in many applications, it is known to use vibrations in the preparation or use of a material in the liquid or viscous state.

These vibrations can be used to promote the mixing of the components of the material, to evacuate by gravity any bubbles of air or gas present in the material, to promote the dispersion of the material in an arbitrary array of elements or in an enclosure. fill, or to compact the material after dispersion.

In each of these methods, the characteristics of the vibrations used, such as their amplitude, their frequency and their nature, are chosen according to the characteristics of the material and of these components, and according to the desired effect.

Indeed, improper use of vibrations can lead to damage to the material.

For example, during the preparation of a part in a composite material comprising fibrous reinforcements embedded in a resin matrix, inappropriate vibrations may lead to embrittlement of the bonds during solidification or fibrous elements, to the occurrence of microcracks, undesirable heating or delamination, deterioration of the surface condition of the finished product, premature wear of tools and production, and sometimes even destruction of the part being manufactured.

The present invention aims to improve a pultrusion process by the use of appropriate vibrations.

By pultrusion is meant a continuous process for manufacturing a section of composite material in which a reinforcement, for example fibers packaged in a reel, is impregnated with a matrix, for example a thermosetting resin by passing through a bath, and pulled through a die gradually ensuring the shaping of the composite material to the section of the prof ilé to achieve.

In addition, resin may be injected at the beginning of the die, and at least a portion of the die is heated to effect polymerization of the thermosetting resin.

Various documents of the prior art describe the use of vibrations in pultrusion processes.

For example, the German document DE-19754381 provides for vibrating the reinforcements and the resin at different stages of a continuous process of manufacturing a profile by pultrusion.

It is mainly intended to use ultrasound during the impregnation step and during the shaping step.

But it is also expected to transmit vibrations to the means guiding the fibers before and after their impregnation, and the means pulling the product after its passage through the die.

Various vibration generating means are described, but only the ultrasound range is used in the process described in German DE-19754381.

Another Japanese document JP-7016938 provides for vibrating the shaping tool of a pultruded section in order to obtain a surface condition without defects. It is intended to use vibrations of less than ultrasonic frequency.

According to a disadvantage of the pultrusion installations described in these two documents of the prior art, the shaping tool, or die, is entirely subjected to the same vibrations.

Consequently, since the polymerization of the matrix takes place between the inlet and the outlet of the die, the same vibrations are applied to the liquid phase, to the glass transition phase and to the solid phase of the composite material.

Therefore, except to make a compromise, the vibrations used can not be optimized for each of the different phases of the composite material.

In addition, exposure of the thermosetting matrix to vibrations at the beginning of its polymerization, ie in the glass transition phase of the composite material, can cause embrittlement of bonds during solidification or damage to the fibrous reinforcement.

The present invention aims to overcome these disadvantages of the prior art.

For this purpose, the subject of the invention is a method of manufacturing by pultrusion a piece of composite material, the process consisting in continuously manufacturing a profile made of composite material from a reinforcement impregnated with a matrix and drawn at through a die progressively ensuring the shaping of the composite material up to the section of the profile to be produced, the manufacturing method comprising at least three successive steps performed in the die: a first step of starting shaping the material composite, an intermediate stage of beginning of hardening of the matrix, and a final stage of end of hardening of the matrix and end of shaping of the composite material, the manufacturing process being characterized in that it plans to apply vibrations at the die during the first and / or during the last step, and in that it provides not to apply vibrations to the die during the intermediate step. The present invention also covers a die for the implementation of this method, a pultrusion production line including said die, and a piece of composite material obtained by this method.

Advantageously, the invention makes it possible to use different vibrations in different portions of the die, and thus to optimize the effects of these vibrations for each of the portions.

In addition, the invention also makes it possible to combine the effects of different vibrations in the same portion.

Other features and advantages will emerge from the following description of the invention, a description given by way of example only, with reference to the appended drawings in which:

FIG. 1 is a diagrammatic representation in longitudinal section of a die for implementing the pultrusion manufacturing method according to the invention,

- Figure 2 is a schematic cross-sectional representation of the first or the last portion of a die for carrying out the pultrusion manufacturing method according to the invention.

The invention relates to a method of manufacturing by pultrusion of a piece of composite material.

As illustrated in FIG. 1, this manufacturing method consists in continuously manufacturing a P-section made of composite material from a reinforcement impregnated with a matrix and pulled through a die 10.

The die 10 progressively ensures the shaping of the composite material up to the section of the section P to be produced.

According to the invention, the manufacturing method comprises at least three successive steps carried out in the die 10:

a first step of starting the shaping of the composite material,

an intermediate stage of beginning of hardening of the matrix, and a final step of end of hardening of the matrix and end of shaping of the composite material.

In more detail, in the first step, the matrix-impregnated reinforcement is guided so as to form the composite material of the P-profile.

Optionally, additional matrix is injected into the composite material being formed during this first step.

In the second step, means equipping the die cause, for example by means of heat and a chemical reaction, the hardening of the matrix around the reinforcement R.

Finally, in the third step, the matrix finishes to harden around the reinforcement R, under the effect or not of appropriate means, and thus ends up solidifying the composite material of the P-profile.

According to the invention, the manufacturing method provides for applying vibrations to the die 10 during the first and / or during the last step.

But, the manufacturing process provides above all not to apply vibrations to the die 10 during the intermediate step.

Indeed, during this second step, the solidification of the composite material being initiated, vibrations may weaken the bonds during formation or damage the reinforcement R.

In a preferred embodiment, vibrations are applied to the die 10 during the first step and the last step.

The first and the last step of the process having different functions, the vibrations used are different in the two steps.

Different vibrations have different frequencies, different amplitudes, and / or different natures: sinusoidal, pseudo-sinusoidal, pulsed periodic, etc.

Still in a preferred embodiment, the manufacturing method according to the invention provides for applying to the die vibrations whose frequency is taken between 40 and 500 Hz in the first step, and vibrations whose frequency is taken between 500 and 8000 Hz in the last step, the frequencies taken in these frequency ranges for each of the steps being able to bring different improvements to the material composite and / or different advantages in the implementation of the method.

Preferably, the amplitude of the vibrations used in the first step is less than 1 millimeter, and the amplitude of the vibrations used in the last step is less than 0.5 millimeter.

Always preferably, the vibrations used in the first and the last stage are sinusoidal.

In an optimized embodiment, the manufacturing method provides for simultaneously applying vibrations of different frequencies in the first step and / or in the last step.

Thus, it is for example possible, in the first step and / or in the last step, to accumulate the advantageous effects of vibrations of different frequencies taken in the aforementioned frequency ranges.

The simultaneous application of different vibrations also makes it possible to obtain interferences or resulting frequencies: beat frequencies, subtraction and addition of frequencies, harmonic frequencies, etc., which can reinforce the previous improvements and advantages, or even of to procure new ones.

According to another characteristic, the section P of composite material being manufactured along a longitudinal axis L, the vibrations used in the first and / or in the last step are applied parallel to the longitudinal axis L of the profile P composite material .

Alternatively or additionally, in the case where the pultruded profile P is cylindrical in shape, the vibrations can be applied perpendicular to the longitudinal axis L of the profile P composite material. These vibrations perpendicular to the axis of the P profile provide advantages similar or additional to those obtained through longitudinal vibrations.

In an application particularly targeted by the present invention, the matrix of the composite material of the profile P is a thermosetting resin, and the reinforcement is made of fibers, and preferably of carbon fibers.

Also, in order to obtain the polymerization, and thus the hardening, of the resin during the intermediate step, it is intended to heat the composite material during this step.

Optionally, a heating of the composite material in the last step can also be provided to finish the polymerization of the resin.

The characteristics of the process given previously, especially the frequency ranges, are particularly suitable for an application in the manufacture of a pultruded P profile with thermosetting matrix and fibrous reinforcement R.

Also, in this particular application and during the first step of the method, the vibrations used lead to a significant improvement in the wetting between resin and fibers and a more efficient removal of the resin, and allow to achieve a better rate of reinforcement.

And, during the last step of the process, the vibrations used lead to a better surface state of the P-profile.

But, in general, in the first and in the last stage of the process, the vibrations used make it possible to obtain a better regularity in the tensile forces of the fibers and a reduction in these tensile forces, a better geometric distribution of the fibers in the composite material, better dimensional stability and better homogeneity of the composite material of the P-section, which makes it possible to envisage the production of P-profiles of high geometric precision. Finally, the precise choice of the characteristics of the vibrations used in the first and / or in the last stage of the process is a function of the nature and characteristics of the matrix, for example its viscosity, and the nature and characteristics of the reinforcement. composite material forming the profile P, but also other external parameters, such as the mass of elements forming the die.

This precise choice is therefore left to the skilled person who can implement the necessary tests to find the appropriate vibrations.

According to a preponderant factor, this choice must take into account the vibrations transmitted to the composite material via the die 10.

Even if the vibrations transmitted to the composite material are attenuated, and therefore lower than those experienced by the die 10, they must be limited so as not to damage the composite material.

Thus, in the first step, the objective is to control the vibrations transmitted to the matrix of the composite material, while in the last step, the objective is to minimize the vibrations transmitted to the hardened composite material, and even avoid transmitting vibrations to the cured composite material.

FIG. 1 schematically illustrates a die 10 that can be used for carrying out the pultrusion manufacturing method that has just been described.

It is recalled that the process consists of continuously manufacturing a profile P made of composite material from a reinforcement R impregnated with a matrix and drawn through said die 10 which progressively ensures the shaping of the composite material. up to the section of the profile P to achieve.

Of course, the longitudinal axis of the die 10 coincides with the longitudinal axis L of the P profile pultruded. According to the invention, the die 10 comprises at least three successive portions: a first portion 11 starting the shaping of the composite material, an intermediate portion 12 initiating the hardening of the matrix, and a last portion 13 finishing the hardening of the matrix and finishing the shaping of the composite material.

The various portions (11, 12, 13) are hollow and contiguous so as to present a continuous T hole making it possible to progressively shape the composite material of the section P which passes therethrough.

In an application in which the matrix of the composite material of the profile P is a thermosetting resin, the intermediate portion 12, and possibly the last portion 13, are equipped with heating means causing said polymerization, the heating temperature being a function of the characteristics of the resin .

In order to be able to subject the composite material of the section P to vibrations, the first portion 11 and / or the last portion 13 are / are respectively connected to at least one vibratory exciter (14, 15).

And, in order to avoid subjecting the composite material to vibrations during the intermediate stage of the process, the intermediate portion 12 is decoupled in vibrations from the portion or portions (11, 13) connected to a vibratory exciter (14). , 15). In one embodiment of the die 10 for the use of longitudinal vibrations, the first portion 11 and the last portion 13 are each connected to at least one vibratory exciter (14,15) parallel to the longitudinal axis L of the die .

In order to allow longitudinal oscillations of the first and the last portions (11, 13), each portion (11, 13) is respectively mounted on a support (18, 19), for example constituted by slides, allowing a translation in a direction parallel to the longitudinal axis L, the supports (18,19) being integral with the frame 23 of the die 10. And, each portion (11,13) is mounted on a base (20,21) connected to the support (18,19) and to the vibratory exciter (16,17).

In addition or alternatively, and as illustrated in FIG. 2, when the die 10 is cylindrical in shape of the composite material section P, the first portion 11 and / or the last portion 13 are / are connected to at least one vibratory exciter (16, 17) perpendicular to the longitudinal axis L of the die.

More precisely, so that each portion (11, 13) oscillates in rotation about the longitudinal axis L when it is driven by the vibratory exciter (s) (s) (16, 17), each vibratory oscillator (16 , 17) is mounted in a direction (D16, D17) perpendicular to the longitudinal axis L of the die.

In this case, the supports (18, 19) are designed to allow a rotation of the portions (11, 13) around the longitudinal axis L.

In order to ensure continuity in the shaping of the composite material during the use of longitudinal vibrations and / or perpendicular to the longitudinal axis L, the first portion 11 and the last portion 13 are axially connected to the intermediate portion by connecting means 24 around the longitudinal axis L of the die.

In a variant using only longitudinal vibrations, the connecting means 24 may take the form of centering studs (25,26,27,28) arranged in housings (31,32,33,34) made partially in the intermediate portion 12 and partially in the first portion 11, and partially made in the intermediate portion 12 and partially in the last portion 13.

Obviously, the centering studs (25,26,27,28) are mounted along axes parallel to the longitudinal axis L of the die.

In a variant using vibrations perpendicular to the longitudinal axis L, the connecting means 24 may take the form of centering rings 29 disposed in recesses 30 made partially in the intermediate portion 12 and partially in the first portion 11, and made partially in the intermediate portion 12 and partially in the last portion 13.

Finally, in the case of shaping a hollow profile or profile open P, the die 10 may comprise a vibrating mandrel 35 oscillating along the longitudinal axis L.

Advantageously, the vibrating mandrel 35 may comprise a first portion 36 oscillating along the longitudinal axis L only in the first portion 11 of the die 10 and / or a last portion 37 oscillating along the longitudinal axis L only in the last portion 13 of the die 10.

The first portion 36 and the last portion 37 of the vibrating mandrel 35 may also be connected to independent vibratory exciters to use different vibrations in the first portion 11 and in the last portion 13 of the die.

Preferably, the first portion 36 of the mandrel 35 is subjected to substantially identical vibrations to those experienced by the first portion 11 of the die, and the last portion 37 of the mandrel 35 is subjected to vibrations substantially identical to those experienced by the last portion 13 of the sector.

Obviously, the vibratory mandrel 35 also comprises in the intermediate portion 12 of the die 10 an intermediate portion 38 decoupled vibrations of the first portion 36 and / or the last portion 37 when these parts oscillate longitudinally.

The present invention also covers a production line by pultrusion of a piece of composite material including a die 10 as just described and used for the continuous manufacture of a profile P composite material. And, the present invention also covers a piece of composite material made from a profile P composite material continuously manufactured according to the pultrusion manufacturing method which has just been described.

Claims

1. A method of manufacturing by pultrusion of a piece of composite material, the method of continuously manufacturing a profile (P) of composite material from a reinforcement (R) impregnated with a matrix and pulled through a die (10) progressively shaping the composite material up to the section of the profile (P) to be produced, the manufacturing method comprising at least three successive steps performed in the die (10): a first start step of forming the composite material, an intermediate stage of beginning of hardening of the matrix, and a final stage of end of hardening of the matrix and end of shaping of the composite material, the manufacturing method being characterized in that it plans to apply vibrations to the die (10) during the first and / or during the last step, and in that it provides not to apply vibrations to the die (10) during the eta intermediate pe.

2. Manufacturing method according to claim 1, characterized in that vibrations are applied to the die (10) during the first and the last step, and in that the vibrations used are different in the two stages, the vibrations having different frequencies, amplitudes, and / or natures: sinusoidal, pseudo-sinusoidal, periodic pulse, etc.

3. Manufacturing process according to claim 1 or 2, characterized in that the vibrations applied in the first step have a frequency between 40 and 500 Hz, and in that the vibrations applied in the last step have a frequency between 500 and 500 Hz. and 8000 Hz.

4. Manufacturing method according to one of claims 1 to 3, characterized in that vibrations of different frequencies are applied simultaneously to the die (10) in the first step and / or in the last step.

5. Manufacturing process according to one of claims 1 to 4, characterized in that the vibrations are applied parallel to the longitudinal axis (L) of the profile (P) of composite material.

6. Manufacturing process according to one of claims 1 to 5, characterized in that, the pultruded profile (P) being of cylindrical shape, the vibrations are applied perpendicularly to the longitudinal axis (L) of the profile (P) in composite material.

7. Manufacturing process according to one of claims 1 to 6, characterized in that the matrix is a thermosetting resin, and in that the polymerization of the resin is obtained by heating the composite material during the intermediate step, and possibly in the last step.

8. Manufacturing process according to one of claims 1 to 7, characterized in that the reinforcement () consists of fibers, for example carbon fibers.

9. Manufacturing process according to one of claims 1 to 8, characterized in that the matrix is injected into the composite material being formed during the first step.

10. Spinneret (10) for carrying out the method of manufacturing by pultrusion of a composite material part according to one of the preceding claims, the method consisting in continuously manufacturing a profile (P) made of composite material from a reinforcement (R) impregnated with a matrix and drawn to the traders of said die (10) progressively ensuring the shaping of the composite material to the section of the profile (P) to be produced, the die (10) comprising at least one at least three successive portions: a first portion (11) beginning the shaping of the composite material, an intermediate portion (12) initiating the hardening of the matrix, and a last portion (13) ending the curing of the matrix and finishing the shaping of the composite material, the various portions (11, 12, 13) being hollow and contiguous so as to present a continuous hole (T) gradually shaping the composite material of the profile (P ) which passes through it, the die (10) being characterized in that the first portion (11) and / or the last portion (13) are / are respectively connected to at least one vibratory exciter (14, 15), and in that the intermediate portion (12) is decoupled in vibrations from the or portions (11, 13) connected to a vibratory exciter (14, 15).

11. Spinneret (10) according to claim 10, characterized in that the first portion (11) and the last portion (13) are each connected to at least one vibratory exciter (14,15) parallel to the longitudinal axis (L ) of the die.

12. Die (10) according to claim 10 or 11, characterized in that the die (10) performs a cylindrical shaping of the profile (P) of composite material, and in that the first portion (11) and / or the last portion (13) is / is connected to at least one vibratory exciter (16, 17) perpendicular to the longitudinal axis (L) of the die (10).

13. Spinneret (10) according to one of claims 10 to 12, characterized in that the first portion (11) and the last portion (13) are axially connected to the intermediate portion (12) by connecting means (24). ) about the longitudinal axis (L) of the die.

14. Die (10) according to claim 13, characterized in that the connecting means (24) take the form of centering studs (25,26,27,28), or centering rings (29) arranged in housings (31, 32, 33, 34), or respectively in recesses (30), partially formed in the intermediate portion (12) and partially in the first portion (11), and partially formed in the intermediate portion (12). ) and partially in the last portion (13).

15. Die (10) according to one of claims 10 to 14, characterized in that the die (10) performs a shaping of a profile (P) hollow or open profile, and in that the die ( 10) comprises a vibrating mandrel (35) oscillating along the longitudinal axis (L).

16. Die (10) according to claim 15, characterized in that the vibratory mandrel (35) comprises a first portion (36) oscillating along the longitudinal axis (L) only in the first portion (11) of the die (10) and / or a last portion (37) oscillating along the longitudinal axis (L) only in the last portion (13) of the die (10).

17. Spinneret (10) according to one of claims 10 to 16, characterized in that the intermediate portion (12), and optionally the last portion (13), are equipped with heating means.

18. Production line by pultrusion of a composite material part, the line being characterized in that it includes a die (10) according to one of claims 10 to 17 and used for the continuous manufacture of a profile (P) of composite material.