Abstract: Rotary twister element suitable to keep under tension the fibres during the twisting operation in a frictional open-end spinning process, constituted by a solid, hollow, reduced-thickness element with perforated skirt, which is internally provided with a suction duct defining a longitudinal slot, the edge of which constitutes the thread formation line, is suitably inclined relatively to the general trix of the same solid, hollow element, as a function of the direction of rotation of the solid element, and of the direction of thread extraction. Also a screen is provided for the air dragged by the rotation of the solid element, which may have a cylindrical shape, a cone frustum shape, or the shape of any other revolution solid.

Abstract: A friction open-end spinning process wherein the fibers of the feeding fiber sliver, once separated into discrete fibers, are sucked by a suction slot on a revolving twister element provided with a perforated surface, to feed the free end of the yarn being formed. The process is characterized in that the fibers are fed in a direction parallel to the free end of the yarn being formed, are kept under an adjustable tension throughout the twisting operation, and are subjected to a progressively increasing twist from the open end of the yarn being formed onwards. The device embodying the above process uses a revolving flat disc provided with perforations arranged according to an annulus as the twister element. This element cooperates with a sucking slot, the edge of which, consituting the yarn formation line, is positioned according to a chord of the disc.