ディスク型フリクション仮撚における糸の走行経路: (第1報) ディスク上を走行する糸の経路と張力の解析

Although the false-twisting by means of a friction disk unit is an efficient technique widely applied to manufacture the synthetic fiber yarns conventionally called `textured yarns', the fundamental mechanics operating in the processing, especially the relationship between frictional and extensional forces and paths which a yarn experiences when twisted, is not sufficiently in vestigated to date. This series of reports aims to establish a theory that describes the mechanical behaviors of a yarn in the false-twisting process using a friction disk unit, and to obtain basic information about the yarn path and the frictional forces acting on the yarn . In the theoretical part of this article, the forces balance equations, which determined a yarn path contacting with the toric surface of a single false-twisting-disk unit, were developed on the basis of differential geometry of curved surfaces. In the experimental part, the path shape of a yarn contacting with the toric surface of twisting disk was photographed and simultaneously the yarn tension was measured under several combinations of processing conditions : the yarn entrance direction and feed velocity, the rotational speed of the twisting disk, etc.The data obtained coincided fairly with analytical estimations and the presented scheme was confirmed to be valid for predicting the behaviors of a yarn in the false-twisting processing using a friction disk unit .