The present invention relates to three-dimensional woven bodies of revolution having complex geometric shape.
Three dimensional woven bodies of revolution after impregnation with a hardenable resin binder and thereafter, machined to precisely desired dimensions have found notable use in ballistic missles and rockets.
In U.S. Pat. No. 3,904,464, a body of revolution is formed by simply winding resin impregnated yarns circumferential within an "urchin" of pins delimiting the longitudinal and circumferential path. Only simple geometric forms are possible and much gluing and hardening is required prior to machining.
A three dimensional body is shown in U.S. Pat. No. 3,834,424 but it is not woven.
French Pat. No. 73/14 956 describes the fabrication by three-dimensional weaving of hollow parts of revolution in which circumferential and radial yarns are layed through a network of longitudinal rods made of polymerized resin. Fabrication of parts of complex form cannot be made but only cylindrical or, with great difficulty, conical parts.
The prior art has, in addition to the indicated drawbacks, a drawback having to do with the quality of the parts obtained. This quality in fact depends directly on the fibre content of the woven parts and hence, on the tamping during weaving. In the prior art, this tamping is obtained either manually or by the binding force induced by the tension of the circumferential yarns used. Tamping by binding force varies with the winding diameter, resulting in variations in the thickness of the part. In addition, in the case of large thicknesses, the binding force decreases from the inside toward the outside of the part, thus leading to a woven material which is heterogeneous in its thickness. The binding force also has a tendency to change the diameter of the courses laid, and this results in the slipping and shifting of fibres, harmful to final product quality.