EP3450606A1 - Method of forming by needling an annular textile preform from a fibrous web twist and machine for implementing such a method - Google Patents

Abstract

The invention relates to a process for the needling formation of an annular textile preform from a helical fibrous web, comprising successively the unfolding of a helical fibrous web (8) from a horizontal platen forming sheet (6) animated a constant and predefined rotating speed N _FS on a horizontal intermediate unwinder (24) driven by a rotating speed N _DI and positioned on a horizontal intermediate plate (22) driven by a rotating speed N _FI , the unwinding of the web helical fibrous process from the intermediate unwinder to a final horizontal unwinder (12) driven by a rotating speed N _DF , and the unfolding of the fibrous web from the final unwinder to a horizontal preform forming plate (18) driven by a speed rotary N _FP variable and predefined to undergo a needling, the N _DI , N _FI and N _DF speeds being controlled so that N _DF is proportional to N _FP , N _IF = (N _FS - N _DF ) / 2, and N _DI = (N _FS + N _DF ) / 2.

Description

Background of the invention

The present invention relates to the general field of needling a helical fibrous web for producing an annular textile preform.

It is known to use a circular type needling machine for producing annular textile preforms intended to constitute the fiber reinforcement of annular pieces made of composite material, in particular brake discs, such as discs made of carbon / carbon composite material. (C / C) for airplane brakes.

A circular needling machine generally comprises a horizontal annular plate on which is laid a helical fibrous sheet, means (most often friction) for rotating the fibrous sheet around the vertical axis of the plate, and a needling device having a needling head extending over an angular sector of the plate and driven in relative vertical movement with respect to the plate. We can refer to the document WO 02/088451 which describes an embodiment of such a needling table.

In the context of the industrialization of the production of annular textile preforms, it is generally intended to associate a helical fibrous web forming table (or spiral sheet) to the needling machine described above. In practice, the web forming table is positioned above the needling table and feeds it continuously into a helical fibrous web. However, if the web forming table has a continuous operation, the needling table discontinuously calls the helical fibrous web. Indeed, the needling table stops feeding the web after cutting the web, during finishing needling, during control operations of the preform, and during the evacuation of the completed preform before taking over complete cycle. The continuous operation of the web-forming machine is thus antagonistic with the discontinuous operation of the needling table.

Object and summary of the invention

The present invention therefore has the main object of providing a process for the needling formation of an annular textile preform from a helical fibrous web which does not have the aforementioned drawbacks and makes it possible to accommodate operations different from the web formation and the needling table.

et $${\mathrm{N}}_{\mathrm{DI}}=\left({\mathrm{N}}_{\mathrm{FS}}+{\mathrm{N}}_{\mathrm{DF}}\right)/\mathrm{2.}$$

This object is achieved by means of a method of needling forming an annular textile preform from a helical fibrous web, successively comprising the unfolding of a helical fibrous web from a horizontal plateau forming a web driven by a speed constant and predefined rotary press N _FS on a horizontal intermediate unwinder driven by a rotating speed N _DI and positioned on a horizontal intermediate plate driven by a rotating speed N _FI , the unwinding of the fibrous helical sheet from the intermediate unwinder to a horizontal unwinder end driven by a rotary speed N _DF , and the unwinding of the fibrous helical sheet from the final unwinder to a horizontal preform forming plate animated with a variable speed N _FP variable and predefined to undergo a needling, speeds N _DI , N _FI and N _DF being controlled so that:
N _DF is proportional to N _FP ; $${\mathrm{NOT}}_{\mathrm{FI}}=\left({\mathrm{NOT}}_{\mathrm{FS}}-{\mathrm{NOT}}_{\mathrm{DF}}\right)/\mathrm{2};$$

and $${\mathrm{NOT}}_{\mathrm{DI}}=\left({\mathrm{NOT}}_{\mathrm{FS}}+{\mathrm{NOT}}_{\mathrm{DF}}\right)/\mathrm{2.}$$

The invention is remarkable in that it proposes to receive and store the helical fibrous web produced continuously by the web forming table on an intermediate unwinder. In particular, the invention allows temporary storage of the web between the web forming table and the needling table to overcome the different operating speeds between these two tables. Thus, when the needling table is to be stopped (for example to evacuate a preform made), the helical fibrous sheet which is continuously produced by the tablecloth forming table accumulates in coils superimposed on the intermediate unwinder pending starting a new cycle of the needling table. It is thus not necessary to stop the tablecloth during the stopping of the preform forming tray.

More specifically, with the control of the speeds N _DI , N _FI and N _DF as defined according to the invention, each time the needling table is stopped, the intermediate plate will perform a complete revolution both. web turns unrolled from the web forming plateau to store a web turn on the intermediate unwinder and another web turn wound in the same direction on the final unwinder.

The web forming plate and the preform forming plate advantageously have respective average speeds which are equal.

Preferably, N _DF = k × N _FP where k is a predetermined constant or variable factor corresponding to servo control of the amount of helical fibrous web in a control chute positioned between the final unwinder and the preform forming tray.

Also preferably, the method further comprises counting the number of turns of helical fibrous web unwound on the intermediate unwinder. This count makes it possible to manage the stopping of the web-forming machine if the maximum (predetermined) quantity of web turns stored on the intermediate unwinder is reached or, conversely, a stopping of the needling machine if the number of revolutions of tablecloth stored on the intermediate unwinder reaches zero.

More preferably, the needling of the helical fibrous web is interrupted at the end of each annular textile preform forming cycle to allow said preform to be evacuated.

The invention also relates to a circular needling machine for implementing the method of forming an annular textile preform from a helical fibrous web as defined above, comprising a horizontal sheet-forming plateau intended to to form a helical fibrous web and animated with a constant and predefined rotary speed N _FS , a horizontal intermediate plate positioned under the web forming plate and driven by a rotating speed N _FI , a horizontal intermediate unwinder positioned on the intermediate plate and driven by a rotating speed N _DI , a final horizontal unwinder positioned under the intermediate unwinder and animated with a rotational speed N _DF , and a horizontal plateau forming preform positioned under the final unwinder and animated with a rotating speed N _FP variable and predefined.

Preferably, the machine further comprises a flow control chute of the helical fibrous web positioned between the final unwinder and the preform forming plate.

The intermediate and final unwinders may each comprise two curved circular conveyor portions disposed opposite one another.

The preform forming plate may comprise a needling head with a vertical movement back and forth relative to the plate.

Brief description of the drawings

• la figure 1 est une vue schématique d'une machine d'aiguilletage circulaire pour la mise en oeuvre du procédé de formation d'une préforme textile annulaire selon l'invention ; et
• la figure 2 est un exemple de chronogrammes cycliques montrant les vitesses des différents éléments de la machine de la figure 1.

Other features and advantages of the present invention will emerge from the description given below, with reference to the accompanying drawings which illustrate an embodiment having no limiting character. In the figures:

• the figure 1 is a schematic view of a circular needling machine for carrying out the method of forming an annular textile preform according to the invention; and
• the figure 2 is an example of cyclic chronograms showing the velocities of the various elements of the machine of the figure 1 .

Detailed description of the invention

The figure 1 illustrates very schematically a circular needling machine 2 according to the invention which is intended for the formation of an annular preform from a fibrous web (or band) helical.

Typically, such a circular needling machine 2 comprises a web forming table 4 intended to form a helical fibrous web (for example by weaving). This tablecloth forming table comprises in particular a horizontal sheet forming plateau 6 on which is positioned the fibrous web 8 being formed.

The sheet forming tray 6 is driven in a rotational movement around a vertical axis 10. The formation of the sheet being an operation can be carried out continuously at the same speed, the sheet forming plateau 6 is more precisely driven by a rotational movement at a rotating speed N _FS which is constant and predefined.

The circular needling table 2 also comprises a final unwinder 12 located below the tablecloth forming table 4, this final unwinder being typically intended to unroll the fibrous web 8 wound on the tablecloth forming tray 6 for the bring to needling.

As described in more detail in the publication EP 2,339,055 , the final unwinder 12 comprises a circular conveyor 14 for rotating the fibrous web 8 around the vertical axis 10. This circular conveyor 14 may advantageously be formed of two curved conveyor portions 14a, 14b which are each half-shaped. -disque and which are arranged opposite one another (the straight edges of these conveyor portions are parallel and face to face). The direction of rotation of these curved conveyor portions is directed so as to cause a complete turn of 360 ° to the fibrous web 8 about the vertical axis 10.

The circular conveyor 14 of the final unwinder 12 is controlled to turn the fibrous web 8 around the vertical axis at a rotating speed N _DF .

Under the final unwinder 12 is positioned a needling table 16 which is intended to ensure a circular needling of the fibrous web 8 unwound from the final unwinder.

The needling table 16 is known, for example from the publication EP 2,339,055 , and will not be described in detail. Briefly, it comprises a horizontal preform forming plate 18 which receives the fibrous web to drive it in rotation about the vertical axis 10 at a rotational speed N _FP , this speed being adjustable.

During this rotation, the fibrous web undergoes a needling by a needling head (not shown in FIG. figure 1 ) extending over an angular sector of the web-forming platen and moved vertically back and forth relative thereto.

Note that as described in the publication EP 2,339,055 , the fibrous web 8 which is unwound from the circular conveyor 14 of the The final unwinder is conveyed to the preform forming tray 18 through a web flow control chute 20 extending vertically between the final unwinder and the preform tray. The combined presence of a circular conveyor and such a chute makes it possible to deliver fibrous web without tension, the latter being guided vertically towards the preform forming plate by means of the chute.

The rotary speed N _FP of the preform forming plate 18 is by nature non-constant since it is necessary in particular at the end of each preform formation cycle by needling (after the needling of a predefined number of layers of fibrous web) to stop the rotation of the plate to evacuate the preform before starting a new cycle. In particular, this rotary speed N _FP is a predefined datum which is different from the rotary speed N _FS of the web forming plate 6.

According to the invention, provision is made to position a horizontal intermediate plate 22 under the tablecloth forming platter 22, driven by a rotating speed N _FI , this intermediate plate 22 being intended to ensure a temporary storage of a certain number of laps. fibrous web 8 between the web forming machine and the needling machine.

Furthermore, still according to the invention, a horizontal intermediate unwinder 24 is positioned on the intermediate plate 22 and driven by a rotating speed N _DI . As for the final unwinding device previously described, this intermediate unwinder includes a circular conveyor 26 that can be composed of two curved conveyor portions 26a, 26b which are each in the form of a half-disk and which are arranged facing each other , the direction of rotation of these curved portions being directed so as to cause a complete turn of 360 ° to the fibrous web 8 about the vertical axis 10.

The control of the circular needling machine according to the invention, and in particular the rotational speeds of the various elements that constitute it, is as follows.

As previously indicated, the speeds N _FS (of the web formation plateau 6) and N _FP (of the preform formation plateau 18) are input variables that are known. Moreover, these plates 4, 18 have respective average speeds which are equal.

1. (a) N_DF est proportionnelle à N_FP ;
2. (b) $${\mathrm{N}}_{\mathrm{FI}}=\left({\mathrm{N}}_{\mathrm{FS}}-{\mathrm{N}}_{\mathrm{DF}}\right)/\mathrm{2};$$
   
   et
3. (c) $${\mathrm{N}}_{\mathrm{DI}}=\left({\mathrm{N}}_{\mathrm{FS}}+{\mathrm{N}}_{\mathrm{DF}}\right)/\mathrm{2.}$$
   

As for the speeds N _DI (intermediate unwinder 24), N _IF (intermediate plate 22), and N _DF (final unwinder 12), they are controlled so as to verify the following control equations:

1. (a) N _DF is proportional to N _FP ;
2. (B) $${\mathrm{NOT}}_{\mathrm{FI}}=\left({\mathrm{NOT}}_{\mathrm{FS}}-{\mathrm{NOT}}_{\mathrm{DF}}\right)/\mathrm{2};$$
   
   and
3. (C) $${\mathrm{NOT}}_{\mathrm{DI}}=\left({\mathrm{NOT}}_{\mathrm{FS}}+{\mathrm{NOT}}_{\mathrm{DF}}\right)/\mathrm{2.}$$
   

The control equation (a) is a consequence of the presence of the regulation channel of the unwinding of the web 20 between the final unwinder and the preform forming plate. More precisely, this equation is equivalent to: _## EQU1 _## in which k is a predetermined constant or variable factor corresponding to a control regulation of the quantity of helical fibrous sheet in the regulation chute.

The control equations (b) and (c) are in particular intended to ensure storage of several turns of fibrous web on the intermediate unwinder without constraining the fibrous web between the intermediate unwinder and the final unwinder and without constraining the fibrous web at the exit of the tablecloth forming tray.

The figure 2 shows an example of a speed control of the various elements of the circular needling machine according to the invention.

More precisely, this figure shows an example of cyclic chronograms of the speeds N _FP , N _FS , N _F1 , and N _DI satisfying the control equations (a) to (c) according to the invention.

In this example, the speed N _FS of the tablecloth is programmed to be constant and equal to 6 rpm. Likewise, the speed N _FP of the preform forming plate is programmed to vary cyclically between 0 and 10 rpm.

It will be noted that a zero N _FP speed corresponds to the stop time of the preform forming plate necessary to evacuate the preform once it has been completed and to reset the machine before restarting for a new training cycle. This downtime is typically of the order of 50s or so.

From these predefined N _FS and N _FP speeds, the operator controls the speeds N _DF , N _FI and N _DI so that they verify the aforementioned equations (a) to (c). The cyclic chronograms of these speeds verifying these equations are represented on the figure 2 .

On the figure 2 is also represented the cyclic chronogram N _TS which represents the number of turns of fibrous web that accumulates on the intermediate unwinder. In this example, the control of the speeds N _DF , N _FI and N _DI makes it possible to continuously accumulate between 2 and 10 turns of fibrous web on the intermediate unwinder.

Thus, thanks to the presence of the intermediate unwinder, it is in particular possible to keep the speed N _FS of the tablecloth forming plate constant despite the stops of the preform forming plate necessary to evacuate the preforms at each end of the cycle and to restart this tray.

Claims (9)

A method of needling formation of an annular textile preform from a helical fibrous web, comprising successively: the unwinding of a helical fibrous web (8) from a horizontal sheet-forming plateau (6) animated with a constant and predefined rotary speed N _FS on a horizontal intermediate unwinder (24) driven by a rotating speed N _DI and positioned on a horizontal intermediate plate (22) driven by a rotating speed N _FI ; unrolling the helical fibrous web from the intermediate unwinder to a final horizontal unwinder (12) driven by a rotating speed N _DF ; and unrolling the helical fibrous web from the final unwinder to a horizontal preform forming plate (18) driven by a variable and predefined N _FP rotational speed to undergo needling; the speeds N _DI , N _FI and N _DF being controlled so that:
N _DF is proportional to N _FP ; $${\mathrm{NOT}}_{\mathrm{FI}}=\left({\mathrm{NOT}}_{\mathrm{FS}}-{\mathrm{NOT}}_{\mathrm{DF}}\right)/\mathrm{2};$$

and $${\mathrm{NOT}}_{\mathrm{DI}}=\left({\mathrm{NOT}}_{\mathrm{FS}}+{\mathrm{NOT}}_{\mathrm{DF}}\right)/\mathrm{2.}$$

The method of claim 1, wherein the web forming platen (6) and the preform forming platen (18) have respective average speeds that are equal. Method according to one of claims 1 and 2, wherein N _DF = kx N _FP where k is a predetermined constant or variable factor corresponding to servo control of the amount of helical fibrous web in a control chute (20) positioned between the final unwinder (12) and the preform forming plate (18). The method of any one of claims 1 to 3, further comprising counting the number of turns of helical fibrous web unwound on the intermediate unwinder. A method according to any one of claims 1 to 4, wherein the needling of the helical fibrous web is interrupted at each end of annular textile preform forming cycle to allow said preform to be evacuated. A circular needling machine (2) for carrying out the method of forming an annular textile preform from a helical fibrous web (8) according to any one of claims 1 to 5, comprising: a horizontal sheet-forming tray (6) for forming a helical fibrous web and driven by a constant and predefined rotating speed N _FS ; a horizontal intermediate plate (22) positioned under the web forming plate and driven by a rotating speed N _FI ; a horizontal intermediate unwinder (24) positioned on the intermediate plate and driven by a rotating speed N _DI ; a final horizontal unwinder (12) positioned under the intermediate unwinder and animated with a rotating speed N _DF ; and a horizontal preform forming plate (18) positioned under the final unwinder and animated with a variable and predefined N _FP rotational speed. The machine of claim 6, further comprising a control chute (20) for unwinding the helical fibrous web positioned between the final unwinder (12) and the preform forming tray (18). Machine according to one of Claims 6 and 7, in which the intermediate (24) and final (12) unwinders each comprise two curved circular conveyor portions (26a, 26b, 14a, 14b) arranged opposite one of the 'other. Machine according to any one of claims 6 to 8, wherein the preform forming plate comprises a head needling movement with a vertical movement back and forth relative to the plateau.

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