NUMERICAL ANALYSIS OF THE EFFECT OF ROTARY NAVEL ON SPINNING TENSION AND FALSE TWIST TORQUE IN ROTOR-TYPE OPEN-END SPINNING

Abstract

The effect, on the spinning tension and false twist torque, of a rotary navel rotating in the same direction as that of the rotor was investigated. Differential equations were derived from the equilibrium of forces acting on the yarn element as it passes over the navel. Then, they were solved numerically based on some considerations on the geometrical position of the yarn. It was found that the navel rotation changes the spinning tension and the false twist torque; and that the angle of yarn direction at the edge of the navel affects their changes as well as the friction coefficient between the navel and the yarn. The results of numerical analysis were supported by experimental evidence. The use of the rotary navel to diminish the exceeding peripheral twist extent (PTE) improved the tenacity, the elongation and the initial modulus of the spun yarn. A navel on which curved-grooves were cut was used by way of trial to change the yarn direction at the edge of the navel. In result, actual reduction in yarn tension was not only observed, as was expected through the numerical analysis, but also brought about a spinning tension lower than the possible least one that had been so far supposed to be attained when friction is absent.