Process and apparatus for the spinning of fiber yarns, possibly comprising at least one core

A device for the spinning of yarns of fibers containing at least two strands, which comprises:

• means for producing at least two strands formed of at least one roving of fibers and at least one continuous filament, said producing means comprising a pair of rolls for feeding a strand of fibers, a pair of belts for drawing the strand, a pair of rolls for drawing the strand, and a condenser located between the drawing belts and the drawing rolls;
• means for eliminating the continuous filament, said eliminating means comprising shears;
• means for false twisting the strands;
• means for adjusting the tension of the strands, located downstream of the twisting means, said adjusting means comprising delivery rolls whose speed is adjusted with respect to the speed of the drawing rolls;
• means for twisting the stands to form a thread;
• means for winding the thread;
• means for doubling the thread formed by the strands, said doubling means comprising a doubling frame;
• means for increasing the strength of the thread between winding of the thread on a bobbin and twisting of the thread upon the doubling of the thread, said increasing means comprising false twisting by winding the thread around a rod forming a certain angle with the thread and located between the winding of the thread on the bobbin and the twisting of the thread at a distance from a point of assumption of twist less than the length of the fibers.