A study on the dynamic motion of floating fibers in the double apron drafting process

The ring spinning frame featuring the double-apron drafting device is the most widely used method due to its various advantages. The finite element method and experiments were conducted to study the double-apron drafting unit and the novel drafting system. The novel drafting system is characterized by a curved drafting zone and curtate floating zone due to the elimination of the double-apron drafting unit’s double rubber aprons and the innovation of the pins. The finite element results of the double-apron drafting unit and novel drafting system demonstrate that the external friction field in the drafting zone of the double-apron drafting unit is composed of straight-line segments from the pin nip to the middle roller nip. In contrast, the force in the novel drafting system is akin to undulations and exhibits stronger and smoother distribution. In experiments, the double-apron drafting unit and novel drafting system were installed on the ring spinning and compact spinning frames, namely the double-apron drafting unit-ring spinning, double-apron drafting unit-compact spinning, novel drafting system-ring spinning and novel drafting system-compact spinning, to study the slippage rates and yarn properties. It can be seen that the slippage rates of rubber aprons in the double-apron drafting unit-ring spinning vary from 5.84% to 6.89%, while the slippage rates of the lattice apron in the novel drafting system-ring spinning range from 0.39% to 0.66%. In addition, the yarn properties produced by the novel drafting system-ring spinning and novel drafting system-compact spinning, including yarn evenness, imperfections and strength, outstrip those produced by the double-apron drafting unit-ring spinning and double-apron drafting unit-compact spinning.

Section: Resultsmentioning

confidence: 99%

Finite element modeling and experimental investigation between the novel drafting and double-apron drafting systems

Quan

Cheng

et al. 2022

“…Based on the two-velocity hypothesis, some other researchers tested the FAP distribution in a different drafting system with the method of the tracer fiber technique. [10][11][12][13][14][15] They are trying to build the relationship between the unstable movement of floating fibers and drafting parameters, and thus provide a basis for further research. It was found that the FAP distribution in simple roller drafting is more dispersed over a longer range, while the FAP distributions in the double apron drafting zone and the drafting zone with pressure bar are more concentrated and closer to front roller nip line.…”

mentioning

confidence: 99%

Study on the influence of drafting forms in front drafting zone of ring spinning frame on fiber motion and yarn quality

Shen

Meng

Shang

et al. 2023

Self Cite

Double apron drafting is the general drafting form in the front zone of the ring spinning frame. In the double apron drafting system, the top apron and the bottom apron form an elastic tensor gauge, which can better control the movement of floating fibers and improve yarn quality. In order to investigate quantitatively the influence of the top apron and bottom apron on fiber movement and yarn quality in the double apron drafting system, the differences of fiber acceleration point distribution, yarn irregularity and yarn strength spun by double apron drafting, single apron drafting and simple roller drafting under different process conditions were compared. Compared with simple roller drafting, double apron drafting and single apron drafting can effectively control the fiber movement in the drafting zone. With the increase of fiber length, the difference between the distribution of fiber acceleration points obtained by double apron drafting and that obtained by single apron drafting gradually decreases. When the fiber length is greater than 32 mm, the difference is small. Besides, by analyzing the improvement rate of the top apron and bottom apron on yarn irregularity and yarn strength under different drafting settings, it was found that the overall improvement rate of the bottom apron on the yarn quality was higher than that of the top apron, especially for manmade fiber yarns. Even in some cases, the strength of viscose yarn spun by the single apron drafting process is higher than that of the double apron drafting process.

The influence of the friction field on accelerating position distribution

Fan,

Wang,

Zhang

et al. 2024

In accordance with the tenets of displacement deviation theory, the distribution of accelerating positions was the main reason for the uneven output sliver. To elucidate this phenomenon, a dynamic drafting model with controllable fiber proportion was developed in this paper to simulate the accelerating process of the floating fiber. The model was employed to investigate the impact of the friction field on the distribution of accelerating positions, achieved through the manipulation of friction field distribution and fiber proportion in the drafting zone. The simulation results indicated that, with various drafting conditions, the friction field at the position with a higher slow fiber proportion always made the accelerating position distribution closer to the front roller. In addition, the duration of the friction field influence on the fiber floating process was found to be directly proportional to its effect on the accelerating position distribution. Furthermore, there was a critical slow fiber proportion, which increased in tandem with the augmentation of slow fiber proportions in the drafting zone. The friction field at the position where the proportion of slow fibers was higher than the critical slow fiber proportion made the accelerating position distribution closer to the front roller; otherwise, the friction field made the accelerating position distribution closer to the back roller. This study can offer a valuable reference for designing more effective friction field distribution to improve the output sliver quality.