Manufacturing a ring spun slub yarn using multi-channel drafting technique

In this paper, we propose a novel method for manufacturing a ring-spun slub yarn through multi-channel drafting using a computer numerically controlled (CNC) ring spinning frame. Through controlling the speeds of the feeding rollers, the apron rollers and the spindle, we can manipulate the blending ratio, linear density and twist of the spun yarn online, offering more degrees of freedom to configure fibers in the spun yarn. Furthermore, we develop a digital control system in conjunction with a CNC ring spinning machine, in which each CNC ring spinning machine serves as a drone machine that receives commands from a central computer. A self-developed management platform is designed to help the client manage these drone machines via online regulation. At last, a series of experiments are conducted to examine the impact of manufacturing parameters on the structures and properties of slub yarn. We found that the descriptive parameters that affect the breaking force of the slub yarn samples are the slub length, slub distance, slub multiplier, and roving ratio. The parameters that affect the breaking elongation are obtained as the slub length, slub distance, slub multiplier, and twist coefficient.