Method for manufacturing composite shafts with injection molded, rigidized bladder with varying wall thickness

A method for manufacturing a composite shaft comprising:

• providing an impregnated fibrous material comprising a fiber impregnated with a hardenable polymeric material;
• forming an impregnated fiber preform by wrapping the impregnated fiber material around a shaped bladder having an inner cavity for pressurization of the bladder;
• placing the assembly of the bladder and the impregnated fiber preform into female tooling, the bladder being the sole support for the impregnated fiber in the female tooling, the female tooling having inner dimensions to form a shaft with a middle portion of the shaft having a diameter larger than adjacent portions on either side of said middle portion or having a diameter smaller than said adjacent portions, the bladder having a wall of variable thickness to permit outer contours of the bladder to conform to inner contours of the female tooling;
• pressurizing the bladder to press the impregnated fiber against the female tooling;
• heating the tooling while maintaining pressure in the bladder to form a hardened composite shaft of the polymeric material;
• releasing the pressure in the bladder;
• removing the bladder from the interior of the shaft.