28—Theory and Measurements of the Lashing-End Radius of Doubled Yarns

Abstract

The theoretical radius of the free extremity of a length of yarn wound on to a bobbin and rotating with it is calculated and it is shown that this radius compares well with actual measurements on doubled yarns in the dry state. Hence, given the yarn count and diameter and the bobbin diameter and angular velocity, the lashing-end radius can be found from a single curve. Observations have also been made on the variation (due to evaporation) of this radius with time for wetted doubled yarns. Air-drag is shown to be a major factor in determining the size of the lashing-end radius, and the paper includes some measurements of the air-drag of doubled yarns (which are found to have slight differences from singles yarn of the same observed diameter). A curve which enables the air-drag of doubled yarns to be computed from their observed diameters is also given.