Process for the production of a multidirectional textile preform and piece of composite material incorporating said preform

Abstract

A process for the production of a textile preform from interlaced filaments or sections of filaments, using a support ( 16 ) of a shape appropriate to the preform, on which are applied superposed layers of filaments or sections of filaments crossed in at least two directions, the layers being interconnected by filaments or sections of filaments which pass through them, and the filaments or sections being stretched or held on the support ( 16 ) by pins ( 18 ). The method further includes the step of reimplantation of the pins ( 18 ) by offsetting them, so as to avoid the concentration of defects inherent in the use of pins.

1 . Process for the production of a textile preform from interlaced filaments or sections of filaments, comprising a support ( 16 ) of a shape appropriate to the preform, on which are applied superposed layers of the filaments or sections of filaments crossed in at least two directions, said layers being interconnected by means of filaments or sections of filaments which pass through them, and said filaments or sections being stretched or held on said support ( 16 ) by pins ( 18 ), characterized in that it comprises a step of reimplantation of the pins ( 18 ) by offsetting them, so as to avoid the concentration of defects inherent in the use of pins.  
     
     
         2 . Process for the production of a preform according to  claim 1 , characterized in that the pins ( 18 ) are offset approximately in the direction of the filaments to limit the concentration of the defect induced by the inclination of the pins ( 18 ).  
     
     
         3 . Process for the production of a preform according to  claim 1 , characterized in that the pins ( 18 ) are offset approximately in a direction perpendicular to the filaments to reduce the concentration of the defect appearing between the pins between which are stretched the filaments or sections of filaments.  
     
     
         4 . Process for the production of a preform for which the surface increases during superposition of the layers, particularly of cylindrical, conical or truncated conical shape, according to  claim 1 , characterized in that the number of pins ( 18 ) is increased during the reimplantation phase so as to increase the number of filaments or sections disposed in the direction of the generatrices.  
     
     
         5 . Process for the production of a preform comprising a truncated conical or conical portion, according to  claim 1 , characterized in that the filaments ( 12 ) are deposited at the level of the conical or truncated conical portion, by angular sector, so as to form chevrons ( 20 ), these latter terminating to the extent the radius decreases so as to obtain a constant proportion of filaments.  
     
     
         6 . Process for the production of a preform according to  claim 5 , characterized in that it comprises at least one step of reimplanting by offsetting longitudinally and angularly the pins necessary for the production of the chevrons ( 20 ).  
     
     
         7 . Process for the production of a preform according to  claim 5 , characterized in that the number of chevrons per angular sector is increased during reimplantation.  
     
     
         8 . Piece of composite material comprising a textile preform produced according to  claim 1 , embedded in a matrix of one of a resin, ceramic, carbon, and metal.