Simulation on the fiber arrangement and distribution in the drafting zone

Abstract

Roller drafting is an indispensable and fundamental procedure in attenuating the sliver to an adequate linear density during the spinning process. In this study, the drafting dynamic process was reflected in the arrangement containing hooked fibers and straight fibers, and the fiber straightness in the drafting zone in real-time. The drafting process was implemented from the initiation of the sliver head moving into the drafting zone to the achievement of the straightening process for all fibers in the sliver. The developed model demonstrated that the simulated weight distributions of various fibers, including the total fibers, back fibers, front fibers and floating fibers, were more in line with the actual results than the simulative ones based on the previous drafting model with the simulation of the straight fiber arrangement in the sliver. In conclusion, the drafting model with the application of the hooked fiber arrangement was effective and precise in quantizing the drafting process of a sliver with many hooked fibers, such as a cotton card sliver. Moreover, the drafting model can offer the theoretical foundation for setting the drafting parameters from the perspective of the distributions of slow-floating fibers and fast-floating fibers.

Isometric fiber distribution in the roller drafting zone

“…For isometric fibers, their total fiber distribution curve close to the back nip is relatively flat, while the rest tend to linear descent. 4,20,21 Therefore, the fiber distribution curve was divided into two parts, a horizontal line and an oblique line.…”

“…2,3 A feasible scheme to meet the challenge is to understand the motion state of fibers under different drafting parameters, such as the fiber type, fiber length, roller-setting (the distance between back nip and front nip), draft ratio (the ratio of front roller speed to back roller speed), doubling number (the number of input slivers), and sliver linear density. [2][3][4] The motion state of fiber depends on the force acting on the fiber. In a drafting zone, two pairs of rollers with different speeds, the front rollers with fast speed and the back rollers with slow speed, grip the fiber sliver, and the force acting on fiber is affected by the contact probability with fast-moving and slowmoving fibers in addition to the fiber characteristics and the pressure force applied on the fibers.…”

“…2,3 A feasible scheme to meet the challenge is to understand the motion state of fibers under different drafting parameters, such as the fiber type, fiber length, roller-setting (the distance between back nip and front nip), draft ratio (the ratio of front roller speed to back roller speed), doubling number (the number of input slivers), and sliver linear density. 2 –4…”

Study of sliver irregularity caused by fiber acceleration motion during the drafting process

“…4,[23][24][25][26] Furthermore, the simulation of the roller drafting process has been carried out based on the model of fiber arrangement in the sliver. 2,3,[27][28][29] Nevertheless, in these models, the fiber in the input sliver before the drafting simulation was regarded to be randomly arranged and the additional irregularity caused by the fore-spinning process was not considered. In the carding sliver, the sliver irregularity calculated from the idealized random fiber arrangement is regarded as the theoretical irregularity, which is far lower than the actual sliver irregularity.…”