Method for manufacturing by molding elongate and hollow workpieces made from composite material, molding device for implementing the method and workpieces obtained

A transmission shaft, being comprised of composite material, the shaft comprising:

• ancillary workpieces, each ancillary workpiece being comprised of at least one of a group consisting of:
• a bearing ring, a lever, and a pinion, the ancillary workpieces being of different internal diameters,
• wherein the shaft is obtained by the method comprising the steps of:
• producing an initial preform on a circular or ovoid mandrel without creating shrinking, by superimposing several distinct layers, each layer being entirely made up either of a winding of fibers arranged in helicoids that are all parallel, or from the rolling of one or more plies of pre-impregnated unidirectional fibers correctly oriented in a helicoidal manner, while the helicoids of one layer have the opposite helix angle with respect to that of the helicoids of the adjacent layer,
• cutting said initial preform to the correct length so as to form a preform assembly,
• placing the preform assembly in a female mold previously equipped with internal drainage means and pressurizing means,
• bringing an impregnation resin to a softening temperature and pressurizing the preform assembly at both ends until the preform assembly is deformed by a diametrical increase in dimensions, until the preform assembly matches a female shape of the female mold,
• bringing the impregnation resin to polymerization temperature and pressure in order to allow each ancillary workpiece to consolidate, each ancillary workpiece having an external shape becoming consistent with an internal shape of the female mold,
• opening the female mold and removing each ancillary workpiece from the female mold,
• machining final shapes of the ancillary workpieces, and
• placing, before the step of placing the initial preform in the mold, at least one ancillary workpiece in the mold having an axial central opening, into which said initial preform is introduced.