Effect of Mechanical Processing Variables in Drawing on Sliver Irregularity

Abstract

The present work examines the influence of draft distribution at the drawframe upon sliver irregularity under varying conditions of drawframe processing. The investigations were made at the first and second passage of drawing in carded mixings and at post-combed drawings in combed mixings, on slow-speed drawframes with Shirley draft distribution and high-speed Whitin drawframes. Eccentricity of top roller is shown to be one of the causes of slippage and sliver irregularity in slow-speed drawframes. Increasing the top roller loading is helpful in overcoming to some extent the deterioration in irregularity caused by an eccentric top roller. Roller slip at the front position caused by eccentricity in the roller has the most detrimental effects on sliver irregularity. Use of lower break draft under these conditions increases the sliver irregularity considerably. Eccentricity in the top roller in the second and third position causes more slippage, but the effect on irregularity of sliver is only marginal. Reduction of break draft increases slippage of front, second, and third top rollers even when they are true, but it does not affect sliver irregularity. The optimum roller setting at the front zone in conventional and high-speed drawframes depends upon the break draft and lies at a higher level at lower break draft. Thus, at close front zone setting, higher break draft gives a more regular sliver, while at wide setting, lower-break draft gives better results. The sliver irregularity at the optimum setting is, however, not much affected by the break draft.