Method for manufacturing a one-piece preform for a composite structure

Abstract

A method for producing a one-piece preform for a composite structure includes the following steps: positioning a plurality of bundles of warp threads over two pairs of harnesses; making movements of low amplitude of each of the pairs of harnesses so as to make at least two adjacent and separate layers; and making movements of higher amplitude of the pairs of harnesses so as to at least partially link the at least two adjacent layers to an least one portion of the preform.

What is claimed is: 
     
         1 . A method for producing a one-piece preform for composite structure comprising said one-piece preform forming a reinforcement of the composite structure and a matrix, wherein said one-piece preform is achieved by a three-dimensional weaving method using a weaving loom, and the weaving loom comprises at least one reed and at least two pairs of harnesses, each of the harnesses comprising a plurality of heddles, and each of the heddles being equipped with a plurality of eyelets of which each one is a passage of a warp yarn, the at least two pairs of harnesses being distributed at distinct altitudes from the weaving loom so as to form a plurality of levels, said method comprising the following steps:
 positioning a plurality of bundles of warp yarns on the at least two pairs of harnesses;   movements of low amplitude of each of the at least two pairs of harnesses for a predetermined length of said warp yarns, in such a manner that, during an introduction of weft yarns, at least two adjacent layers are achieved, independent on at least one portion of the one-piece preform; and   movements of increased amplitude, with respect to said movements of low amplitude, of the at least said two pairs of harnesses, for a predetermined length of said warp yarns, in such a manner that during the introduction of the weft yarns, the at least two adjacent layers are at least partly linked on at least one portion of the one-piece preform.   
     
     
         2 . The method for producing a one-piece preform for composite structure according to  claim 1 , further comprising a step of positioning on the weaving loom means for separating the adjacent layers of the one-piece preform. 
     
     
         3 . The method for producing a one-piece preform for composite structure according to  claim 2 , wherein the means for separating the adjacent layers comprise at least one stem that is positioned, during the weaving, between the at least one reed and the at least two pairs of harnesses, and between the adjacent layers. 
     
     
         4 . The method for producing a one-piece preform for composite structure according to  claim 1 , wherein at least one part of the bundles of warp yarns is positioned on at least one level of the at least two pairs of harnesses so as to achieve, during the introduction of the weft yarns, a current section of the one-piece preform, and at least one bundle of warp yarns is positioned at a distinct altitude from a same harness so as to achieve, during the introduction of weft yarns, at least an extra thickness of one of the two adjacent layers. 
     
     
         5 . The method for producing a one-piece preform for composite structure according to  claim 1 , wherein several warp yarns are disposed between two levels of the weft yarns. 
     
     
         6 . The method for producing according to  claim 1 , further comprising a step of leaving at least one weft yarn free so as to define a machining area without impact. 
     
     
         7 . The method for producing a one-piece preform for composite structure according to  claim 1 , further comprising a step of cutting out and/or folding the one-piece preform so as to give a shape close to a shape to be given to the composite structure. 
     
     
         8 . The method for producing a one-piece preform for composite structure according to  claim 1 , wherein the warp yarns and the weft yarns are woven according to an interlock type weaving method. 
     
     
         9 . A weaving loom for implementing the method of producing according to  claim 1 , further comprising a plurality of pairs of harnesses disposed side by side in the weft direction so as to allow an independent control of each of said harnesses.