Air Dynamics Characteristics Analysis of Air Splicer

The internal airflow of an untwisting chamber clearly affects the untwisting performance as determined by the appearance of the untwisted yarn end. This study established a geometric model of an untwisting chamber comprising an intake tube and untwisting tube, and adopted the renormalization-group k-" turbulence model to simulate the airflow patterns inside chamber structures having three varying parameters. These were the chamfer angle of the intake nozzle, rotation angle of the intake nozzle, and eccentric distance between the intake nozzle and untwisting tube. The chamber angle of the intake nozzle mainly induces a radial flow from the axial flow in the intake nozzle. The strength of the circumferential airflow in the untwisting tube, which is converted from the radial flow, is affected by the combined effects of the rotation angle of the intake nozzle and the eccentric distance between the intake nozzle and untwisting tube. An experimental bench that employed a high-speed camera to capture yarn movement was designed to verify the numerical results. Comparisons between simulation and experimental data show that the structural parameters of the untwisting chamber affect the airflow patterns and consequently the performance of untwisting the yarn end.Pneumatic yarn splicing used to join two separated yarn ends is a key technology for promoting yarn quality. As a complex process, pneumatic splicing can be obviously divided into an untwisting stage and a mingling stage. Firstly, a high-speed jet generated from compressed air is used to untwist two yarn ends intermingled by fibers in a helical manner, causing the yarn ends to become individual fibers, in an untwisting chamber. The two untwisted yarn ends are then dragged into a mingling chamber in an overlapping relationship using yarn clamps. Finally, another strand of airflow opposed to the rotation of untwisting airflow is applied to join the two separated yarn ends to form a neat strong yarn.There are many factors affecting the performance of the pneumatic splicing of yarn, such as the splicing inlet pressure, splicing duration, overlap length of the two yarn ends, and physical characteristics of the yarn. 1 Owing to the importance of splicing parameters, researchers have investigated the effect of such factors on the quality of twisted yarn normally characterized by strength and diameter, both experimentally and theoretically.Li presented the working principle of the pneumatic splicer and described how the factors affect the performance of splicing yarn. 2 Focusing on the dynamic response characteristic of the pneumatic actuator in the air splicer, Chattopadhyay et al. 3 realized rapidity of splicing by modifying the mechanism parameters.

mentioning

confidence: 99%

“…Based on the modern computational mechanics method, Wang et al. 10 optimized the structure of the splicing chamber, providing the feasible means and methods in the air splicer theory research and optimization design.…”

mentioning

confidence: 99%

Study on effects of structural parameters on untwisting performance in pneumatic yarn splicing

Shi

Chen

et al. 2015

“…By analyzing airflow in the pneumatic splicer with different structures and sizes, Wang et al. 15 optimized the structural parameters of the mingling chamber. From the analysis of the effects of a groove structure on airflow characteristics in the mingling chamber and the splice strength, Wu et al.…”

mentioning

confidence: 99%

Study on the filament motion and joint forming mechanism in the pneumatic yarn splicing process

Shi

2016

Pneumatic yarn splicing is a complex process concerning the winding of multi-filaments in a spiral airflow field. In this study, the joint forming mechanism is revealed by experimental and numerical methods. The whole splicing process in a specific-design splicing device was captured by a high-speed camera. A renormalization-group k-[Formula: see text] turbulent model was also adopted to simulate the distribution of the airflow field in the mingling chamber. From experimental images and numerical results, the motion of the filament with one fixed-end and a joint forming mechanism was discussed in detail. It is found that different parts of a large aspect ratio filament present completely different behavior due to its flexibility. The free-end of the filament is wound around the opposite yarn under the impact of circumferential airflow. Meanwhile, the bending deformation occurs at the middle part of the filament owing to the strong impact of the injecting airflow, and then it is dragged toward the fixed-end of the filament by axial airflow to prevent the forming of a joint. It is believed that the initial overlapping length has a decisive role in the forming of the splice joint. A proper overlapping length is of benefit to achieve enough winding loops at the free-end of the filament to resist the dragging force exerted by axial airflow and obtain a successful splice subsequently. The splicing experiments with different overlapping length and inlet pressure were conducted to verify the correctness of this analysis.

“…In this way they could determine the best inlet condition for a particular chamber geometry. Wang et al 8 concluded that a rounded shape of a splicing chamber is better than a square or a hexagon.…”

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confidence: 99%

“…The shape of the splicing chamber must be designed to drive the airflow creating the flow pattern needed for the splicing goal (e.g. create vortices; Wang et al 8,9 ). The air jet pressure and velocity should be appropriate to create sufficient aerodynamic forces, but when they become excessive the appearance and the quality of the yarn will be influenced (Webb et al 10 ).…”

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confidence: 99%

Numerical prediction and experimental analysis of ends-together yarn splicing

Osman

Meulemeester

Malengier

et al. 2016

3Pneumatic yarn splicing is a technical process for joining two yarn ends together. The 4 process involves injecting compressed air into a splicing chamber. Inlet pressure and 5 chambers slope determine the main parameters affecting this process. In this paper, large 6 eddy simulation (LES) of the flow field in four selected splicing chambers is carried out. 7The chambers are used for splicing ends-together yarns. The results of these simulations are 8 analysed to investigate first the effects of the inlet pressure. Second, the effects of the 9 geometry of the chambers on the flow field inside the splicing chambers are determined. 10These effects are studied and analysed to interpret the experimental results, which have 11 been obtained using the same splicing chambers. This provides further insight into the 12 parameters which are important to obtain good splicing characteristics. It is demonstrated 13 that the volume of the splicing chamber and the location of the air inlet channel play crucial 14 roles in the splicing of the end-together yarns.