23—deblending in Roller-Drafting

Abstract

Roller-drafting causes fibre shear, and the consequential longitudinal migration of short fibres with respect lo long ones leads lo fibre-deblcnding. Furthermore, the drafting of a strand with a varying blend ratio along its length leads to variations in drafting-wave activity along its length. Thus, even with a perfectly autolevelled sliver, variations in blend become translated into irregularily in linear density in later processes. The textile material carries potential errors with it as it passes from one process to the next.Data presented in this paper show quasi-harmonic variations in blend and in fibre properties along the length of slivers, rovings, and yarns. The error wavelengths of the variations were similar to those found in the normal testing of linear density. There is thought to be a connexion.

Quality and quality control

“…11.10(a) was made by recording the changing separation of the centers of the front rolls of a drawframe [8]. Such errors are harmonic and the repeat period may be expressed as error wavelength.…”

Problems and Possibilities in Sliver Monitoring

“…Classical theory [ 1,3,4,5] held that the fiber length was one of the most important determinants of the problem, and many writings have assumed that the length distribution of the fiber involved is constant. In fact it is quite variable [8,9] in many respects. There is a sort of variable blending between fibers of different length.…”

“…There is a sort of variable blending between fibers of different length. Variations in blend lead to later variations in linear density [8] because of the shear effects in drafting. Hence variations in fiber length caused by carding or earlier machines introduce latent errors that develop into real errors during later processing.…”