Study On The Movement Characteristics Of Fiber In Key Parts Of The Rotor Spinning Unit

Rotor spinning is an open-end spinning method using air as working medium.Although the rotor spinning has been used in industrial production,broken ends are easy to appear in production.And the strength of yarn is low.In order to fully understand its mechanism,it is necessary to conduct a further study of fiber-airflow interaction related to it.The rotor spinning unit mainly consists of an opening unit,a fiber transfer channel and a rotor cup.They are key parts in the rotor spinning unit,which affect the quality of rotor yarn.Based on the fiber's transfer process,this paper mainly focuses on transport characteristic of fiber in key parts of the rotor spinning unit.First,a two-dimensional model of the opening unit combined with fiber transfer channel is established.Characteristics of airflow field in fiber transfer channel are investigated by the model.The trash-separate process in opening unit is simulated using Discrete Phase Model(DPM).And the structure of the opening unit is redesigned.Second,the Immersed boundary-Lattice Boltzmann method(IB-LBM)is used to simulate the movement and deformation of fibers in the fiber transfer channel.Third,the effect of two variables,the rotor speed and the angle of slide wall,on the movement of fiber are studied by establishing a three-dimensional model of the rotor cup.Finally,numerical simulation results are partially verified by experiments by setting up an experiment bench.The conclusions obtained in this paper are as follows:1.The opening roller speed and the negative pressure at the outlet have a little impact on the length of vortex in the axial direction.The effective area for fiber conveyance reduces as the opening roller speed increases,while it enlarges as the absolute value of negative pressure at the outlet of transfer channel increases.Greater pressure value is conducive to fiber transmission.Different opening roller speed has different removal efficiency for different sizes of trash particle.2.For fibers that have a wavy initial configuration would experience varying deformations in the transfer process.The deformations of fibers that have a wavy initial configuration enlarge with the increase of distance between two fibers.Distance between two fibers should be kept after the carding of fiber.Reducing the speed of opening roller and enlarging the fiber transfer channel are helpful to reducing the unfavorable factors for the fiber transfer.In addition,movements of two fibers show a similar morphological distribution in general.3.The high-speed rotor will form a very thin velocity boundary where the fibers speed up greatly in an instant.Fiber would collision after the fibers' landing on the slide wall,which will increase the vibration and abrasion of the rotor bearing as well as the rotor itself.The distribution of fiber in the groove is closely related to the rotor speed.With other parameters being held constant,the higher the rotor speed,the longer and thinner the fibrous ring.A larger angle of the slide wall tends to bring a concentrated distribution of fiber on the slide wall.