PROCESS FOR THE PREPARATION OF A FIBROUS PREFORM OF EVOLUTIVE THICKNESS FOR MANUFACTURING A PART IN COMPOSITE MATERIAL OF THE CARBON OR CERAMIC MATRIX TYPE.

摘要

In a part of the preform to be produced where it has a reduced thickness by forming a recess, a mask (181, 182 ...) is inserted between two neighboring layers (121, 122, ...) consisting of a film thin in a material capable of being crossed by the needles during needling while opposing the substantial passage of fibers taken by the needles, and each layer is cut, after it has been needled, along a corresponding line at the contour of the preform recess, at the level where the layer is located in the preform. A mask located between two cut strata has an area at least equal to that inscribed between the cut lines of the two strata, so that the parts of strata (121, 122, ...) delimited by the cut lines are not strongly linked to the rest of the preform by needling and that the recess can be formed by proceeding, after needling of all the layers, to the removal of the parts of cut layers and to the peeling of the masks.