Method for producing preforms with application of a binder to dry fiber, and corresponding machine

Method for producing preforms, by layup of fibers on a layup surface, comprising

• application of a binder on at least one continuous flat dry fiber, comprising two opposite main faces and two longitudinal edges, the opposite main faces including a first main face and a second main face, and
• layup of said fiber provided with binder by means of a layup head in order to form a preform,
• wherein the application of binder on the fiber is carried out by means of at least one fiberizing nozzle comprising a discharge orifice supplied with liquid or pasty binder, and one or several injection orifices supplied with pressurized gas, in such a way that said nozzle is able to deliver the binder in the form of a spiral filament, the spirals of filament being deposited on a first main face of the fiber running underneath the nozzle in order to obtain a fiber provided with filaments of binder, and,
• wherein during the application of binder, the spirals of filament that are deposited on the first main face of a fiber fold at the longitudinal edges of the fiber and flatten against the second main face of the fiber, in such a way as to obtain the fiber provided with filaments of binder on each main face.