In this study, the tracer fiber method was used to determine the accelerated point distribution in both the break draft and main drafting zone of the drawing frame with varying different draft parameters. Viscose, cotton, and polyester slivers were used respectively. For the different parameters, the tracer fibers of known length were embedded in the single sliver strand, and measurements of their positions before and after drafting were taken. These measurements of the positions of tracer fibers before and after drafting were then used to deduce the nature of the fiber movement, thus determining the distribution of the accelerated points. The accelerated point distribution under different parameters was obtained. Gauss distribution was found to suitably describe the accelerated point distribution curve under different parameters used in this study. The pressure bar to some degree imparts a significant control of floating fibers within the drafting zone. The relationship between the sliver unevenness and the accelerated point variance (CV) was also discussed.

The quality of blended yarn depends on the uniformity of the blending of the multi-component fibers in the yarn, and sliver blending is a process necessary for mixing fibers. The movement of fibers directly affects the distribution and mixing of fibers in the sliver. In this paper, the sliver blending process was simulated, and a method for the evaluation of sliver blending irregularity was proposed. The effects of passages of drawing and blending ratio on the sliver mixing uniformity were studied and verified both by experiment and simulation. The results show that the blending irregularity decreases gradually and tends to be stable with the increase of the passages of blending drawing. The more similar the blending ratio of the two components with approximately equal linear densities, the easier it is for the component fibers to mix evenly in the sliver. The simulation results are in good agreement with the measured values and previous research results. In addition, the blending irregularity of fiber components in the blended sliver can be predicted by the simulation method.

The blending ratio and blending irregularity of the blended yarn determine its property and quality. In this article, the image processing method was introduced to accurately and conveniently measure the blending ratio and blending irregularity of blended yarn by using images of the blended yarn cross sections. The Euclidean distance peeling method was applied to segment the adhered fibers to make them individual. Then, the fibers were classified according to characteristic parameters of fiber cross section such as color, shape, and area. The experiments were implemented to verify the accuracy and applicability of the image processing method to test the irregularity of blended bundles, slivers, and yarns by different fibers including polyester, viscose, and wool. The results show that the fiber identification error rate of the image processing method for blended bundles, compared with the designed, is less than 2%; the blending irregularity difference rate between image processing method and the manual counting method is less than 5% for blended sliver by sliver blending; the difference rate of the blending ratio of polyester/viscose blended yarn between designed and measured by image processing method is less than 5%, while manual counting method is less than 10%. The findings mean that the image processing method proposed in this article can greatly save labor and time on identifying and counting fibers, and it is a more accurate, convenient, and reliable method to test blending irregularity.

The yarn specific work of rupture is a comprehensive index to characterize the resistance of yarn to mechanical destruction. For blended yarn, it is closely related to the blended ratio of the components. This paper established a model to express the quantitative relationship between the specific work of rupture and the blended ratio in blended yarn. This model was obtained by analyzing the breaking process of blended yarn and summarizing the empirical data. Then, the experimental data were used to verify the established model and a good agreement between the calculated and experimental results was found. According to this model, the curve of the specific work of rupture against the blended ratio can be obtained by simple plotting. Consequently, this work can be used to predict the specific work of rupture for blended yarn with various blended ratios.

A simulation describing the fiber movement during the condensation was conducted, and the effect of the condensation in the carding machine was studied. The simulation results showed that the condensation has the blending and the evening effect on the condensed sliver, which can be explained by the fiber rearrangement. Moreover, the increasing web width and the decreasing condensing length can result in a more uniform sliver. Further, the evening effect of the web width on the web was verified by experiments. The simulation results were in general agreement with the experimental results.