Mechanical analysis and numerical simulation of a multivariate principle curve draft device and analysis of its yarn properties

Friction field distribution is a critical factor in the drafting process, as it affects the fiber bundle movement in the main draft zone. In this paper, a modified draft device, named the multivariate principle curve draft device, which extends the friction field and condenses fiber bundles, has been employed to produce colored spun yarns. To analyze the effect of the modified draft device in the spinning process, mechanical analysis and finite element simulation were applied. In the mechanical analysis, the curvature surfaces of the grooved compactor exert friction force on the fiber bundles to restrain the peripheral fibers, and the relation between the friction and angles of the contact surfaces was concluded. In the numerical simulation, the result shows that the friction force distribution in the curved drafting channel is extended and enhanced, which leads to the forward distribution of the fiber accelerated points. Meanwhile, 28.1 tex blended colored yarns (cotton/polyester/viscose 30/30/40) and 19.7 tex pure viscose colored yarns were spun by the modified and conventional draft sets on a ring spinning machine. The comparative results imply that the modified device ensures outstanding yarn properties, such as yarn evenness, hairiness and imperfections, although there is some decrease in the yarn strength.