Research On The Core Technology Of New Spinning Based On The Air-jet Spinning Mechanism

As the largest textile producer and exporter in the world,it is important for China to realize the sustainable development of textile industry.Textiles are made of yarn,so the importance of spinning is obvious.Although traditional ring spinning has occupied an important position since its birth,its production efficiency is low because of its long spinning process,slow spinning speed and small package capacity,which is not in line with the high-speed development trend of society.So there are some new spinning methods using airflow,among which rotor spinning,jet spinning and jet eddy spinning are more representative.Although these spinning methods improve the production efficiency,due to the existence of drafting roller and twisting part of high-speed rotary parts,the drafting ratio of yarn is limited,and the yarn quality and spinning speed need to be further improved.The structure limitation of jet eddy spinning also leads to poor spinnability of different length fibers.In view of the above problems,the core of spinning method,drafting and twisting,is studied in this paper.Considering the compressibility and continuity of gas flow,high-speed jet of air flow can be realized by pressurization,and flow from high pressure to low pressure spontaneously and continuously,and the wear of fibers is small,it is decided to cancel the roller and high-speed rotary parts,apply drafting and twisting mechanism,and use airflow to draft and twist the whole process to form a new air spinning method.The aim is to improve drafting ratio and spinnability of different length fibers on the premise of ensuring production efficiency,and to further improve yarn quality by improving the parallel straightness of the spun fibers.Although the most accurate verification method is experimental verification,because the structure involved in this study is small and the internal air flow is fast,it is impossible to complete the monitoring of air flow and fiber movement through experiments.When other scholars face similar problems,they study through simulation.Therefore,this paper also uses numerical simulation method to study.The research content is divided into three parts:Firstly,in order to realize parallel stretching of fibers in high speed and high drafting ratio spinning and to improve the spinnability of fibers of different lengths,the tasks that should be accomplished in drafting and twisting parts of spinning process are analyzed and summarized.The drafting part should complete the corresponding multiple drafting of the sliver,and minimize the number of crooked fibers in the sliver.The twisting part is to twist the sliver,so that there is a longitudinal connection between the fibers and fix the yarn.Then,according to the theory of pneumatic conveying and hydromechanics,a three-dimensional structure model of drawing and twisting by air flow is established.Secondly,in order to verify that the above structure can achieve high speed and high drafting multiple spinning,the above structure is taken as a simulation model,and the basic governing equation is selected.Based on theoretical analysis and simulation verification,the realizable k-? model is selected as the turbulence model.By changing the angle between the axis of the jet hole and the horizontal axis,the vertical distance between the outlet center of the jet hole and the entry position of the hollow spindle,and the gas pressure of the jet hole injection,the internal flow fields of different parameters models were simulated by Fluent,and a set of optimal model parameters were selected by coMParing and analyzing the simulation results.Finally,in order to verify that the fiber can reach parallel stretching state in the above-mentioned drawing structure,three-dimensional fiber models with different shapes are established,which are close to the actual situation.Combining with the flow field model in the drawing channel,the fluid-solid coupling calculation model is obtained.The appropriate control equation is selected and the solution platform is set up.The fluid-solid coupling numerical simulation is carried out to analyze the movement and deformation of the fiber.According to the simulation results,the drafting structure was improved,and the optimum condition was that the fibers with different morphologies could reach parallel straightening state.Aiming at the problems existing in the existing spinning methods,including drafting multiple,fiber length adaptability and fiber parallel stretching,this paper analyses the advantages of airflow spinning,establishes a three-dimensional model of airflow drafting and twisting structure,and simulates the flow field inside the structure and the movement of fibers in the flow field inside the draft structure.The parameters and structure are improved by analyzing the simulation results.This study not only provides a new idea for the design of new methods,but also enriches the basic theory of the application of air flow in the field of spinning.