The Measurement of Sliver Properties on the Drawframe

Monitoring applications on the drawframe usually involve the measurement of the linear density of the sliver. However, this measurement is imprecise and inadequate. In this work, variations in fiber grouping and fiber-group length extent were measured on the drawframe. The mass profile in the draft zone was obtained by using a high-speed television camera and analyzed by using image-processing.

The mass-profile curve in the draft zone was shown to contain similar information to a Fibrogram beard. In order to obtain the fiber-group length extent, averaging the mass-profile curve over a short length of the strand was necessary to reduce the noise due to variations in the number of floating fibers and in the fiber grouping. The presence of fibers as groups in the sliver leads to a higher thickness irregularity for the strand. A study on the dimensions and the relative number of groups was carried out. The length of the fiber groups was found to be about 1.5 times the nominal fiber length and varied from breaker drawing to finisher drawing. The clump dimensions across the drafted strand on the drawframe were limited to the size of the input slivers. The input slivers were found to behave almost independently under normal drafting conditions.

The measurement of fiber-group extent on the drawframe may provide a means for monitoring and control. The groupings of fibers explain the use of wide roller settings and the existence of large irregularity ratios earlier in the process-line. The independence in the behaviour of the input strands indicates that roller drafting adds much more irregularity than is often recognized.