VERFAHREN UND VORRICHTUNG ZUR HERSTELLUNG VON RINGFÖRMIGEN WERKSTÜCKEN AUS VERBUNDMATERIAL UND VORFORMLINGE FÜR DIESE WERKSTÜCKE

摘要

PCT No. PCT/FR96/00933 Sec. 371 Date Dec. 17, 1997 Sec. 102(e) Date Dec. 17, 1997 PCT Filed Jun. 6, 1996 PCT Pub. No. WO97/00345 PCT Pub. Date Jan. 3, 1997Preforms for producing annular parts of composite material are produced by winding a strip (1) of fibrous material around an elliptical mandrel (10) to produce an elliptical sleeve which can be cut obliquely, cutting taking place either before or after one or more densification steps. The cutting plane is inclined relative to the right cross section of the elliptical sleeve, and the inner and outer portions of the cut rings are machined to obtain circular elements. Such elements can produce annular parts of composite material having a reduced tendency to delanination under circumferential stress. The superposed layers are needling together during winding. A uniform needling density per unit area can be obtained by controlled displacement of the needle board (5) and of the elliptical mandrel (10) relative to each other as the mandrel turns, to compensate for the eccentricity of the cross section of the mandrel. These methods are particularly suitable for producing brake disk preforms.