Sequential Channelling of Mass Variances in Spun Yarn Manufacturing Processes

Abstract

This research deals with a new method of depicting the irregularity of a spun yarn in terms of the mass density profiles of its roving and sliver. A data acquisition system is introduced for capturing analog signals of fiber strands from an Uster Tester3®. Using the system, a linear relationship can be established between the masses of the fiber assemblies and the amplitudes of the output signals, which are shown to fit a time-series model. In addition, a statistical technique is proposed for separating the input variance and the process variance when a roving is produced from a sliver by the conventional drafting process in ring spinning. A spline method and a cross-spectrum analysis demonstrate that the density profiles of a sliver are channeled down to that of the resulting roving, and suggest a strong possibility for separating and controlling the process variances apart from the input variances.