Method of manufacturing a composite turbomachine blade, and a blade obtained by the method

A method of manufacturing a composite turbomachine blade, the method comprising the following steps:

• a) making a preform by three-dimensional weaving of yarns, said preform comprising both the airfoil and the root of the blade, the yarns including tracer yarns that are visually identifiable and that are disposed at least on the surface of the preform;
• b) cutting out said preform while leaving intact a series of tracer yarns situated along a reference face of the preform, thereby providing a cut-out preform suitable for taking the shape and the dimensions of portions constituting the blade;
• c) pre-deforming said cut-out preform so as to provide a pre-deformed preform;
• d) compacting and stiffening said pre-deformed preform;
• e) providing an injection mold in which said stiffened preform is placed;
• f) injecting into said injection mold a binder comprising a thermosettable resin so as to impregnate the entire stiffened pre-deformed preform and maintain the relative disposition between the yarns of the preform;
• g) heating said injection mold;
• and
• h) extracting from the mold a composite molded part presenting substantially the shape and the dimensions of said blade.