Vortex Yarn Structure Characterization

Vortex Yarn structure is created from mostly parallel arranged fibers, part of which forms the bearing part of the yarn (core) and some are twisted around the core (cover). One end of the fiber can be in the core and the other end is wrapped around the core. The level of twisted fibers is mainly influenced by the speed of the yarn passes through a nozzle, the air pressure in the nozzle and nozzle design, i.e. jets angle, spindle diameter, which is chosen with regard to the fineness of the yarn. On the yarn surface is fibers ribbon that wraps the core at regular intervals.

Assume that the cover layer consists of flat fiber ribbon in a helical trajectory. Ribbon wraps the core in the regular intervals and the number of turns per unit length expressed ribbon twist Z_s. Ribbon axis form a helix on the cylinder with a diameter corresponding to the diameter of the yarn core D_c. Ribbon thickness is neglected. Helix angle of ribbon is b. Among the helix angle of ribbon b, diameter D_c and ribbon twist is valid relationship tgb=p D_c Z_s. Thus it is possible to define the twist intensity and twist coefficient of ribbon similar to ring or rotor yarn. Using image analysis can be measure the wrap length of ribbon, core yarn diameter and evaluate twist, twist coefficient and twist intensity of ribbon.

The main aim of this work is investigation of the effect of technological parameters Muratec machines  (delivery speed, air pressure, diameter of hollow spindle) on the wrap length and twist of ribbon. Influence of ribbon twist on yarn Vortex properties as packing density, diameter, hairiness, strength and elongation is described.