Mechanical design and experimental validation of a helically grooved feeding cylinder for controlling fiber migration during draw-frame drafting

Sliver irregularity generated during draw-frame drafting remains one of the factors limiting yarn quality because transverse fiber migration cannot be completely eliminated through conventional optimization of drafting parameters alone. Although previous studies have improved sliver quality by adjusting roller spacing, pressure, draft ratio, and autoleveling systems, limited attention has been devoted to redesigning feeding-cylinder geometry as a passive fiber-guidance mechanism. In this study, a novel helically grooved feeding cylinder was developed to generate a transverse fiber-centering force that suppresses fiber migration during drafting. A theoretical model based on force equilibrium and D'Alembert's principle was established to explain the fiber-guidance mechanism and quantify the influence of groove inclination on fiber transport behavior. Feeding cylinders with groove inclination angles of 8°, 10°, and 12° were manufactured and experimentally evaluated on an RSB-D 45 draw frame. The effects of groove inclination angle, drafting distance, and pneumatic roller-loading pressure on sliver quality were assessed using the coefficient of mass variation (CVm), coefficient of variation measured over 1-m test lengths (CV1m), and coefficient of variation measured over 3-m test lengths (CV3m), followed by response surface optimization. Among the experimentally tested groove angles, α = 10° produced the lowest sliver-irregularity values, while response surface analysis located the estimated optimum region near 10° within the investigated 8°–12° range. Under the best-performing tested condition ( α = 10°, L = 1.3 mm, P = 310 kPa ), the minimum values of CVm, CV1m, and CV3m were 2.71%, 0.49%, and 0.34%, respectively. The proposed cylinder improved fiber control through passive mechanical guidance without additional sensors or electronic control systems. The study demonstrates that helical-groove engineering provides a practical approach for enhancing sliver uniformity and advancing mechanical fiber-control strategies in modern draw-frame technology.