FR3059267A1 - DEVICE AND METHOD FOR CONTROLLING THE TEMPERATURE - Google Patents

Abstract

The invention relates to a device (100) for controlling the polymerization treatment temperature of a preform (101) comprising fibers and a polymerizable resin, the device (100) comprising a plurality of assemblable modules (108) so as to reversible and each assemblable module (108) comprising at least one Peltier effect cell and at least one heating element assembled to the Peltier effect cell, the device (100) comprising a controller (116) configured to control each buildable module (108) independently of other assemblable modules (108). The invention also relates to a method of manufacturing a workpiece comprising a polymer matrix composite material using such a device.

Description

® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY © Publication number: 3,059,267 (to be used only for reproduction orders)

©) National registration number: 16 61576

COURBEVOIE © Int Cl ⁸ : B 29 C 70/54 (2017.01), F 01 D 5/28, B 29 L 31/08

A1 PATENT APPLICATION

©) Date of filing: 28.11.16. © Applicant (s): SAFRAN AIRCRAFT ENGINES - (30) Priority: FR. @ Inventor (s): CURLIER AUGUSTIN MARC MICHEL and POELLE AMELIE. (43) Date of public availability of the request: 01.06.18 Bulletin 18/22. ©) List of documents cited in the report preliminary research: Refer to end of present booklet (© References to other national documents ® Holder (s): SAFRAN AIRCRAFT ENGINES. related: ©) Extension request (s): © Agent (s): CABINET BEAU DE LOMENIE.

TEMPERATURE CONTROL DEVICE AND METHOD.

FR 3,059,267 - A1 (£ /) The invention relates to a device (100) for controlling the polymerization treatment temperature of a preform (101) comprising fibers and a polymerizable resin, the device (100) comprising a plurality of reversibly assembled modules (108) and each assemblable module (108) comprising at least one Peltier cell and at least one heating element assembled with the Peltier cell, the device (100) comprising a controller (116 ) configured to control each assemblable module (108) independently of the other assemblable modules (108).

The invention also relates to a method of manufacturing a part comprising a composite material with a polymer matrix using such a device.

BACKGROUND OF THE INVENTION The present disclosure relates to the manufacture by infusion of resin of composite parts comprising fibers.

Resin infusion methods offer an economical alternative for the manufacture of large parts with a low section to volume ratio, such as fan blades or parts of the nacelle of a turbojet engine, helicopter blades or wind turbine or aircraft wings.

Referred to by the acronyms "VIMP" for Vacuum Infusion Molding Process or "VARI" for Vacuum Assisted Resin Infusion, these methods consist of forming a film of liquid resin above or below the stack of fibers previously placed in a half-mold closed by a vacuum cover. It is then the action of the vacuum which will compact the system and infuse the resin into the thickness of the part (transverse direction). The fact of traversing the part in the shortest direction makes it possible to improve the filling times of the molds, while limiting the formation of porosities.

The mold is often very expensive because it generally includes an integrated heating and cooling device, such as a resistive or induction heating system or a heat transfer fluid system. Furthermore, the time for designing and manufacturing such a mold is often very long.

Alternatively, the mold may not have an integrated heating and cooling device and the assembly formed from the mold, fibers, resin and the vacuum cover is placed in an oven or in an autoclave in order to polymerize the resin and obtain a composite part comprising fibers.

However, cooking and cooling in an oven or an autoclave does not guarantee the uniformity of the temperature in the room, especially when it has variable thicknesses. Also, generally, the rise and fall in temperature are very slow and can include stages of homogenization of the temperature in the room more or less long, in order to reduce the temperature differences which can coexist at an instant t in the room.

Indeed, differences in temperature in the room are likely to create differences in the polymerization process and therefore differences in chemical and physical properties in the room, which is not desirable. For example, if the resin is heated to a too high temperature, the resin can degrade, which will locally cause a degradation of the properties of the composite part comprising fibers obtained by this process.

OBJECT AND SUMMARY OF THE INVENTION The present description aims to remedy these drawbacks at least in part.

To this end, the present disclosure relates to a device for controlling the polymerization treatment temperature of a preform comprising fibers and a polymerizable resin, the device comprising a plurality of modules which can be assembled reversibly and each module which can be assembled. comprising at least one Peltier effect cell and at least one heating element assembled with the Peltier effect cell, the device comprising a controller configured to control each assemblable module independently of the other assemblable modules.

Thanks to the plurality of modules assembled together in a reversible manner, it is possible to easily adapt to the geometry of the preform. These assemblable modules can for example be arranged on a vacuum cover and therefore be distributed over the preform.

Each assemblable module comprising a Peltier effect cell and at least one heating element, it is possible to impose locally, opposite the Peltier effect cell, a temperature on the preform both in heating and in heating. in cooling. In fact, a Peltier effect cell makes it possible to extract heat and therefore to cool an element against which the cell is arranged. This cooling can vary depending on the input voltage applied to the Peltier cell.

Each assemblable module can be controlled independently of the other assemblable modules, it is possible to heat or cool part of the preform arranged opposite a first assemblable module faster or slower than another part arranged opposite a second assemblable module. It is also possible to envisage having faster heating and cooling speeds than those required when using an oven or an autoclave and / or reducing or even not having a temperature plateau during heating and / or cooling. We can thus advantageously reduce the time required to polymerize a preform and obtain a polymerized part.

One can also reduce the phenomena of exceeding the set temperature of the autoclave or the oven in the preform. These phenomena, also called “thermal overshoots”, can be present in particular when the preform is thick. Thus, for a point located at a certain depth of the preform, the actual temperature may be lower than the set temperature by approximately 10 ° C (Celsius) during the temperature rise. Then, when the setpoint temperature reaches the predefined level, the temperature at this given point approaches the setpoint temperature. Since polymerization is an exothermic reaction, when it begins, it is accompanied by a local increase in temperature. This local increase in temperature at the given point can hardly be controlled and there is a risk that the temperature at the given point exceeds the polymerization temperature of the preform, this temperature possibly going as far as degradation of the polymer following this local overheating. This degradation of the polymer can lead to a defect in the part which may not be acceptable. The part must then be discarded.

Thanks to the presence of Peltier effect cells, it is possible to locally evacuate more efficiently the heat generated by this exothermic reaction. It is therefore possible to increase the heating speed and therefore reduce the time required to polymerize a preform and obtain a polymerized part.

This device can advantageously be used during the manufacture of very small series, such as the manufacture of prototypes, for example during the development of new parts.

Thus, the design and manufacturing time of the mold is reduced because the mold does not have a heating and cooling device integrated into the mold. The same goes for manufacturing costs.

Each assemblable module being reversibly assembled, the assembly of the assemblable modules can be modified easily. It is also possible to reuse the assemblable modules to polymerize other parts and / or parts having different geometries.

Each assemblable module may include at least one temperature measuring element configured to measure the temperature of the preform, the temperature measuring element being disposed adjacent to the assemblable module.

The temperature can then be measured for each module which can be assembled separately. The precision and control of heating and cooling are therefore increased.

Each assemblable module may include a cooling circuit for the Peltier effect cell.

One can thus increase the heat flow which can be extracted from the preform or reduce the tension. Each assemblable module can comprise at least one fastener configured to assemble the assemblable module with an adjacent assemblable module.

It is therefore easy to attach an assemblable module to the neighboring assemblable module. The device can thus easily and quickly adapt to the geometry of the preform.

The fastener may include two fastening parts connected by a flexible part.

The flexible part allows the device to better adapt to the geometry of the preform.

The flexible part can comprise an elastomeric material. The present description also relates to a method for manufacturing a part comprising a composite material with a polymer matrix, comprising the steps of:

assembly of a plurality of assemblable modules each comprising at least one Peltier effect cell and at least one heating element assembled with the Peltier effect cell to form a device as defined above;

- impregnation of a preform comprising fibers with a polymerizable resin so as to form an impregnated preform;

- polymerization of the polymerizable resin by heating the preform impregnated by the device; and

- cooling of the preform impregnated by the device; each assemblable module being controlled independently of the other assemblable modules by the controller.

The preform is heated and cooled by the device. Indeed, it can be envisaged that the heating and cooling is entirely controlled by the device. It is also conceivable that the preform and the device are placed in an oven or in an autoclave and that the assemblable modules make it possible to correct the local temperature during heating and / or cooling.

Likewise, the mold may include a heating element and the assemblable modules make it possible to correct the local temperature during heating and / or cooling.

Thanks to the presence of the assemblable modules, it is possible to design a mold comprising a simplified integrated heating and cooling device. The design and manufacturing time of such a mold as well as the costs related to its design and manufacture are therefore reduced compared to a mold comprising an integrated heating and cooling device not having a device as defined above.

The assemblable modules can be controlled independently of each other by the controller as a function of the temperatures measured by a plurality of temperature measuring elements.

Each assemblable module can comprise at least one temperature measuring element configured to measure the temperature of the preform, the temperature measuring element being placed adjacent to the assemblable module and the assemblable modules can be independently controlled. others by the controller as a function of the temperatures measured by the temperature measuring elements.

BRIEF DESCRIPTION OF THE DRAWINGS Other characteristics and advantages of the invention will emerge from the following description of embodiments of the invention, given by way of nonlimiting examples, with reference to the appended figures, in which:

- Figure 1 is a perspective view from its top of a turbojet fan blade;

- Figure 2A is a schematic sectional view of a device for controlling the polymerization treatment temperature of a preform comprising fibers and a polymerizable resin;

- Figure 2B is a schematic sectional view similar to the view of Figure 2A, the mold comprising heating elements;

- Figure 2C is a schematic sectional view similar to the view of Figure 2A, the device being arranged in an autoclave or an oven;

- Figures 3 and 4 are schematic sectional views of an assemblable module;

- Figure 5 is a schematic view from above of two modules assembled together;

- Figure 6 is a schematic sectional view along the section plane VI-VI of Figure 5;

- Figure 7 is a schematic view of a mode of distribution of the temperature measurement elements;

- Figure 8 is a schematic view of the device having an embodiment of the controller;

- Figure 9 is an abacus for determining the cooling efficiency of an assemblable module.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 represents a blade 10, such as a fan blade of a turbojet engine. This blade 10 comprises a body 12 of composite material comprising fibers and a polymerized resin. The blade 10 comprises a blade head 14, a blade root 16, a trailing edge 18 and a leading edge 20 covered by a leading edge reinforcement 22. FIG. 1 is a view of the blade 10 from its top, that is to say from the blade head 14.

Figure 2A is a schematic sectional view of a device

100 for controlling the polymerization treatment temperature of a preform 101 comprising fibers and a polymerizable resin. In the example shown in FIG. 2, once the resin has polymerized, the preform 101 is intended to form a body 12 of blade 10 made of composite material.

In Figure 2A, the preform 101 is disposed on a half-mold 104 and under a vacuum cover 106. The device 100 and the preform

101 are arranged on either side of the vacuum tank 106.

The device 100 comprises a plurality of assemblable modules 108 reversibly to one another as well as a controller 116 configured to control each assemblable module 108 independently of the other assemblable modules 108.

In Figure 2A, there is also shown, schematically, the extraction of local heat flow 110 and the inlet 112 and the outlet 114 of a heat transfer fluid. However, generally the extraction of the local heat flow 112 is carried out by the discharge 114 of the heat transfer fluid.

3 shows a first embodiment of the assemblable module 108. In the embodiment of FIG. 3, the assemblable module 108 comprises a Peltier effect cell 118 and a heating element 128.

The Peltier effect cell 118 includes a cold plate 120 and a hot plate 122 separated from each other by a series of pn junction semiconductors 124. These pn junction semiconductors 124 are connected to each other. others by conductors 126, for example copper. The cold plate 120 and the hot plate 122 can for example be made of ceramic material.

The assemblable module 108 also includes the heating element 128 assembled to the Peltier effect cell 118 and more particularly to the cold plate 122 of the Peltier effect cell 118. This heating element 128 is disposed between the cold plate 122 and an outer plate 129 of the assemblable module 108. This outer plate 129 is intended to be placed towards the preform 101.

The heat transfer fluid may be air.

Also, in Figure 3, there is shown a fan 130 which is a device for forced convection of air around the assemblable modules 108 when the Peltier effect cell 118 is used to cool the preform 101. We can obviously use other air circulation devices. It is however conceivable not to use such air circulation devices.

As shown in Figures 5 and 6, each assemblable module 108 is at least assembled with another assemblable module 108. For example, each assemblable module 108 may include a module support 138sur on which the assemblable module is fixedly attached . As material for the module support 138, mention may be made of materials having good thermal conductivity, such as aluminum or copper. The assemblable module 108 can for example be fixedly attached to the module support 138 by means of screws and nuts. This module support 138 includes a plurality of fixing holes 148.

In Figure 5, there is shown an assemblable module 108 of square shape and the module support 138 is also of square shape. In FIG. 5, each side of the module support 138 has two fixing holes 148. The square and therefore symmetrical shape of each module 108 and of each module support 138 as well as the presence of the same number of fixing holes 148 on each side of the module support 138 allow easy assembly of the modules 108 which can be assembled together. Indeed, each assemblable module 108 can be assembled with another assemblable module 108 either on one of its four sides.

Two adjacent assemblable modules 108 are assembled to each other by a clip 140. This clip 140 comprises, in the embodiment of Figures 5 and 6, two parts of clips 142 connected together by a part flexible 144. This flexible part 144 can for example be made of elastomeric material, for example natural or synthetic rubber. Each attachment part 142 comprises two pins 146 intended to cooperate with the orifices 148 of a module support 138 in order to secure in movement each assemblable module 108 to the attachment 140.

However, the square shape of the module 108 and / or of the module support 138 is not limiting, for example, the module support could be of hexagonal or rectangular shape. Each side of the module support 138 could have only one fixing hole or have more than two.

As shown in Figure 7, the controller 116 may include a plurality of temperature measuring elements 150 distributed over the preform 101. These temperature measuring elements 150 may be arranged to measure the temperature of the preform 101 at points where the preform has different thicknesses.

We can consider fixing these temperature measurement element 150 on a support 154 disposed on the vacuum tank 106, the support 154 being disposed between the vacuum tank 106 and the assemblable modules 108. We can also consider fix the temperature measuring elements 150 directly to the vacuum tank 106, on the side of the vacuum tank 106 opposite the preform, that is to say on the side of the vacuum tank 106 which faces the modules 108 which can be assembled. These temperature measurement elements 150 may for example be thermocouples connected by cables to the controller 116.

In FIG. 7, the outline of the preform 101 has also been shown in order to facilitate the positioning of the temperature measurement elements 150 on the support 154.

The assemblable modules 108 can be assembled with each other and also fixed on the support 154 or on the vacuum cover 106.

We will now describe a method of manufacturing a part comprising a composite material with a polymer matrix, such as the body 12 of blade 10.

Several assemblable modules 108 are assembled, each comprising at least one Peltier effect cell 118 and a heating element 128, for example by means of fasteners 140. The assembled modules 108 can be fixed on a support 154. They can also be arranged directly on the vacuum cover 106. Each assemblable module 108 is connected to the controller 116.

Similarly, the temperature measuring elements 150 are also positioned on the support 154 or on the vacuum cover 106 and connected to the controller 116.

Take a preform 101 comprising fibers, place it in the mold 104 and then place the vacuum cover 106 on the preform 101, on the side opposite the mold 104.

Then impregnating the preform with a polymerizable resin by creating a vacuum between the mold 104 and the vacuum cover 106.

If the assemblable modules 108 have been directly fixed to the vacuum cover 106, one can proceed to the polymerization step of the polymerizable resin. Otherwise, the assemblable modules 108 are placed on the vacuum cover 106 or the support 154 is attached to the vacuum cover 106, on the side opposite to the preform 101 of the vacuum cover 106. The support 154 may include the assemblable modules 108 already fixed on the support 154 or the assemblable modules 108 can be fixed on the support 154, once the support 154 disposed on the vacuum cover 106. It is also possible to arrange the assemblable modules 108 on the vacuum cover 106 after installation of the vacuum cover 106 on the preform 101.

Once the preform 101 is completely impregnated with polymerizable resin, we go to the heating step.

The temperature of the heating element 128 of each assemblable module 108 is increased, each assemblable module 108 being controlled by the controller 116 independently of the other assemblable modules 108 in order to polymerize the polymerizable resin.

When the resin is polymerized, the heating of the preform 101 is stopped by the heating elements 128 of the assemblable modules 108 and the preform 101 is cooled using the Peltier effect cells 118 of each assemblable module 108, each assemblable module 108 being controlled by the controller 116 independently of the other assemblable modules 108.

The control of the heating or cooling speed of each assemblable module 108 can be carried out as a function of the temperatures measured by the temperature measurement elements 150.

Obviously, each assemblable module 108 being controlled independently of the other assemblable modules 108, the heating or cooling speed, the heating or cooling temperature as well as the heating and cooling time may be different for each assemblable module 108.

The temperature measuring elements 150 being distributed over the preform 101 as a function of the thickness of the preform 101, it can be envisaged that the assemblable modules 108 placed on the preform 101 at points where the preform has thicknesses similar have the same polymerization cycle, that is to say that the heating and cooling parameters of these assemblable modules 108 are identical.

For a given room, the heating and cooling parameters can be determined, for example on another room similar to the given room and we can then consider not using elements for measuring the temperature 150.

In what follows, the elements common to the various embodiments are identified by the same reference numerals.

Figure 2B differs from Figure 2A in that the mold 104 comprises heating elements 105. These heating elements 105 may, for example, be resistive heating elements, heating by heat transfer fluid, inductive heating.

In FIG. 2C, the device 100, the mold 104, the preform 101 and the vacuum cover 106 of FIG. 2A are arranged in an autoclave or an oven 102.

In the embodiments of Figures 2B and 2C, the assemblable modules 108 are auxiliary heating devices which correct the local temperature of the preform 101 during heating and / or cooling by the heating elements 105 from mold 104 or autoclave or oven 102.

4 shows a second embodiment of the assemblable module 108 in which the assemblable module 108 comprises a Peltier effect cell 118, a heating element 128 assembled to the Peltier effect cell 118 and a cooling circuit 132 of the cell Peltier effect 118. The cooling circuit 132 has an inlet 134 and an outlet 136 for the refrigerant. This cooling circuit 132 makes it possible to cool the cold plate 120 more effectively. This allows better efficiency of the Peltier cell during cooling.

Indeed, the efficiency of the Peltier effect cell can be evaluated by the dimensionless merit factor: ZT = TS ² / pÀ, in which Z is the merit factor (in K ′ ¹ - per kelvin), T is the temperature (in K kelvin), S is the Seebeck coefficient of the material (in VK ' ¹ - volt per kelvin), p is the resistivity of the material (in Ωπί - ohm meter) and λ is the thermal conductivity of the material (in Wm ^_1 K ¹ - watt per kelvin meter).

As shown in Figure 9, the efficiency of the Peltier effect cell is a function of the temperature difference between the cold plate and the hot plate of the Peltier effect cell and the dimensionless merit factor ZT.

In an alternative embodiment of the device 100 shown diagrammatically in FIG. 8, each assemblable module 108 may also include a temperature measurement element 150. For simplicity, a single module 108 has been shown in FIG. 8. However, it is understood that the support 154 comprises a plurality of assemblable modules 108 each comprising at least one Peltier effect cell 118, at least one heating element 128 and at least one temperature measurement element 150. The assemblable modules 108 of the FIG. 8 can optionally also include a cooling circuit 132 of the Peltier effect cell 118. These assemblable modules 108 are each connected to the controller 116.

These assemblable modules 108 can also be placed directly on the vacuum tank 106.

The controller 116 will be described a little more in detail. In the embodiment of FIG. 8, the controller 116 includes a processing unit 158 which can receive, as input data, the temperatures measured by the temperature measuring elements 150 as well as the reference polymerization cycle of the preform 101 to be polymerized. From this input data, the processing unit 158 can control each assemblable module 108 separately from the other assemblable modules 108 by sending signals, for example signals with pulse width modulation, also called "PWM" signals. in accordance with the English acronym for “Puise Width Modulation”, with two converters 160, 162. These converters 160, 162 can for example be Buck-Boost type converters arranged between the supply terminals 164, 166 of the supply circuit of each assemblable module 108.

The processing unit 158 of the controller 116 can thus control the heating element 128 and the Peltier effect cell 118 of each assemblable module 108 taking into account the temperature measured near each assemblable module 108, it that is to say for each assemblable module 108.

Although the present description has been described with reference to a specific embodiment, it is obvious that various modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the revendications. In addition, individual features of the various embodiments discussed can be combined in additional embodiments. Therefore, the description and the drawings should be considered in an illustrative rather than restrictive sense.

Claims (9)

1. Device (100) for controlling the polymerization treatment temperature of a preform (101) comprising fibers and a polymerizable resin, the device (100) comprising a plurality of reversibly assembled modules (108) and each assemblable module (108) comprising at least one Peltier effect cell (118) and at least one heating element (128) assembled with the Peltier effect cell (118), the device (100) comprising a controller (116) configured to control each assemblable module (108) independently of the other assemblable modules (108). 2. Device (100) according to claim 1, in which each assemblable module (108) comprises at least one temperature measuring element (150) configured to measure the temperature of the preform, the temperature measuring element ( 150) being arranged adjacent to the assemblable module (108). 3. Device (100) according to any one of claims 1 or 2, in which each assemblable module (108) comprises a cooling circuit (132) of the Peltier effect cell (118). 4. Device (100) according to any one of claims 1 to 3, wherein each assemblable module (108) comprises at least one clip (140) configured to assemble the assemblable module (108) with an adjacent assemblable module (108). 5. Device (100) according to claim 4, wherein the fastener (140) comprises two fastening parts (142) connected by a flexible part (144). 6. Device (100) according to claim 5, wherein the flexible part (144) comprises an elastomeric material. 7. Method for manufacturing a part comprising a composite material with a polymer matrix, comprising the steps of: - assembly of a plurality of assemblable modules (108) each comprising at least one Peltier effect cell (118) and at least one heating element (128) assembled with the Peltier effect cell (118) to form a device (100) according to any one of claims 1 to 6; - impregnation of a preform (101) comprising fibers with a polymerizable resin so as to form an impregnated preform; - polymerization of the polymerizable resin by heating the 5 preform impregnated by the device (100); and - cooling of the preform impregnated by the device (100); each assemblable module (108) being controlled independently of the other assemblable modules (108) by the controller (116). 8. The method of claim 7, wherein the assemblable modules (108) are controlled independently of each other by the controller (116) as a function of the temperatures measured by a plurality of temperature measuring elements (150). 9. The method of claim 7, comprising a device (100) according to claim 2 and wherein the assemblable modules 15 (108) are independently controlled by the controller (116) based on the temperatures measured by the temperature measuring elements (150). 1/7