Abstract
A covered yarn is manufactured using the covering machine. The covering yarn is wound on the core under the ballooning tension of which magnitude depends on the air-drag and the yarn mass per unit length. This tension has been analyzed to investigate the mechanical properties of the covered yarn.
The single node balloon formed by the air-drag and the centrifugal force is discussed by using the theoretical equations derived by Mack, in which the Coriolis force is neglected. The theoretical ballooning curve was computed using the air-drag coefficient CD of cylindrical yarn with diameter d, the specific weight of air γa, the yarn mass per unit length m and the radius b of the yarn package. It was found that the computed single node ballooning curve agrees well with experimental results for filament yarn. The tension in the covering process is approximated by the equation T=mω2l2/2 where ω is angular velocity and l is the radius of lashing-end.
