Abstract: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 af… Show more
“…In the specific drafting simulation, the drafting parameters are input according to the experimental parameters and the accelerated points are randomly simulated based on the experimental value by the trace method introduced by Mupfudze et al 24 Specifically speaking, the fiber accelerated points are calculated from the positions before and after drafting of the dyed tracer fibers embedded in the single sliver. For the simulation, the accelerated points of every fiber are randomly simulated based on the experimental histograms of fiber accelerated-point distribution by the Monte Carlo method.…”
During the spinning process, the roller drafting operation plays a significant role in attenuating the sliver to an appropriate linear density. In this study, the model of fiber arrangement was applied to simulating the roller drafting process in order to shed light on the sliver dynamic behavior in the drafting zone. The drafting process was operated from the high-velocity motion of the first accelerated fiber to the high-velocity motion of the last accelerated fiber. The proposed model showed that the simulated sliver attenuation processes were highly corresponded to the actual sliver attenuation results. In addition, the results revealed that the draft ratio, gauge length, input sliver linear density and accelerated-point distribution form had effective influences on the attenuation curves of sliver linear density, whilst the delivery speed scarcely had any effect. The fiber distributions of various forms were also investigated specifically and quantitatively from the fiber arrangement during the drafting procedure in real time. Furthermore, the sliver dynamic was also described by the mean and CV of fiber velocities within the drafting zone. The obtained simulation results demonstrated that the draft ratio, gauge length and delivery speed had a bearing on the mean velocity of fibers, while the CV of fiber velocities was significantly influenced by the draft ratio, gauge length and input sliver linear density. Besides, the distribution pattern has a valuable contribution to the mean and CV of fiber velocities. In consequence, the new drafting model was validated to be effective in quantizing the drafting process.
“…In the specific drafting simulation, the drafting parameters are input according to the experimental parameters and the accelerated points are randomly simulated based on the experimental value by the trace method introduced by Mupfudze et al 24 Specifically speaking, the fiber accelerated points are calculated from the positions before and after drafting of the dyed tracer fibers embedded in the single sliver. For the simulation, the accelerated points of every fiber are randomly simulated based on the experimental histograms of fiber accelerated-point distribution by the Monte Carlo method.…”
During the spinning process, the roller drafting operation plays a significant role in attenuating the sliver to an appropriate linear density. In this study, the model of fiber arrangement was applied to simulating the roller drafting process in order to shed light on the sliver dynamic behavior in the drafting zone. The drafting process was operated from the high-velocity motion of the first accelerated fiber to the high-velocity motion of the last accelerated fiber. The proposed model showed that the simulated sliver attenuation processes were highly corresponded to the actual sliver attenuation results. In addition, the results revealed that the draft ratio, gauge length, input sliver linear density and accelerated-point distribution form had effective influences on the attenuation curves of sliver linear density, whilst the delivery speed scarcely had any effect. The fiber distributions of various forms were also investigated specifically and quantitatively from the fiber arrangement during the drafting procedure in real time. Furthermore, the sliver dynamic was also described by the mean and CV of fiber velocities within the drafting zone. The obtained simulation results demonstrated that the draft ratio, gauge length and delivery speed had a bearing on the mean velocity of fibers, while the CV of fiber velocities was significantly influenced by the draft ratio, gauge length and input sliver linear density. Besides, the distribution pattern has a valuable contribution to the mean and CV of fiber velocities. In consequence, the new drafting model was validated to be effective in quantizing the drafting process.
“…(4) The fiber accelerated point distribution is assumed to follow a normal distribution. 22,23 Other drafting parameters used in the simulation are summarized in Table 1. Figure 9.Comparison of the output fiber straightness between the simulated and the tested under different drafting settings.…”
In this study, the hook removal of four types of hooks during the drafting process has been investigated, and the theory of fiber straightening was further improved by analyzing the relationship between fiber length, fiber straightness, draft ratio, and the fiber accelerated point. Simultaneously, a time domain model was used to simulate the dynamic drafting process based on the straightening analysis, which provided an approach to capture the dynamic motion of different types of fibers and hook removal in the drafting zone. The model is validated by a previous study and experimental work, with the result that the output fiber straightness is both in a good agreement with those calculated by classical theories and experimental data. The straightening effect of the drafting process on four types of hooks under the same drafting conditions is compared. It is shown that the drafting effect on different types of hooked fibers is varied, with the clumped fiber removed preferentially followed by both end hooks or the trailing hook, whereas the leading hook is the most difficult to remove.
“…Mupfudze et al. 20 investigated the effect of drafting variables on the FAP with dyed fibers in the roller drafting process. Shi and Fan 21 employed fluorescent-tracer fiber to test the FAP in roller drafting, and revealed that the density functions of the FAP were positively or negatively skewed, and mainly distributed at someplace near to the front rollers.…”
The dynamic motion of floating fibers in the drafting process, which can be characterized by fiber accelerated points, has an important effect on the sliver or yarn quality. In this study, the fiber accelerated point during the roller drafting process has been tested with an improved method. In this method, tracer fibers and standard tracer yarns of known length were embedded into the sliver in groups. By adjusting the length and fineness of the standard tracer yarns, it was possible to determine the nip line of the front roller dynamically. Therefore, the fiber accelerated points can be obtained in a continuous drafting process without an external sensor, which is simpler and more convenient, and avoids the experimental error caused by the drawing frame shutdown during the experiment. Based on this method, the effects of the drafting parameters and sliver properties on the fiber accelerated point in the roller drafting process have been investigated. In addition, the coefficient of variance of the sliver ( CVFAP) caused by the fiber accelerated point variation during the drafting process was also calculated. A comparison has been made between CVFAP and the standard deviation of the fiber accelerated points. It is found that a fairly good agreement between these two is seen, and this agreement can also evidence the accuracy of experimental results about the fiber acceleration point.
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