Mechanism Of Mechanically Additional Twisting And Analysis Of Yarn Structure And Properties

Ring spinning technology is irreplaceable in the field of staple fiber spinning due to its advantages such as high raw material suitability,wide production range and controlled product quality,but the twisting and winding components restrict each other and limit production efficiency.This project analyzed the existing methods of improving production efficiency based on ring spinning technology,and designed a mechanical additional twisting device consisting of a holding roller set and two friction discs based on the twisting and winding mechanism of ring spinning and the principle of false twisting.By means of numerical simulation,the force acting on the fiber at the head end is analyzed,and the suitable twist range and effect of the basic parameters of the device are determined by preliminary experiments.Through the spinning experiment,selected the technological parameters of the additional twisting device,and compared with ring spinning,the structure,property and change rule of the auxiliary twisting yarn are tested and analyzed.First of all,a theoretical analysis of the twist of the mechanical additional twisting device is carried out,with a detailed analysis of the forces on the sliver and the distribution of twist.And the device components,transmission mode,power supply and so on are designed and assembly.The main factors of the device are disc diameter,disc surface friction coefficient,disc position,disc speed.Based on the existing dimensions of spinning frame,the size of the disc and the material of the friction surface are determined,in the following experiments,the selection of position and rotation speed were discussed.In the next part,to verify the above theory,a mesh model of the sliver and the head-end free fiber was developed using ANSYS Workbench,and the formation process of twisting and head-end free fiber wrapping on the sliver surface at 45 rpm was obtained.In order to explore the effect of the device,the 300T/m twist yarn which can’t be stabilized by ring spinning is selected to be spun under the action of the device,and the effect of the device is proved from the state of the additional twisting area.Finally,the process parameters of the additional twisting device were optimized and the best performance of the yarn was obtained when the vertical distance of the additional twisting device was 87 mm from the surface of the machine and 7 mm from the front surface of the machine.By spinning yarns with five twist levels(300T/m,400T/m,500T/m,600T/m and 700T/m)at five speeds(15rpm,30 rpm,45rpm,60 rpm and 75rpm).Combined with the experimental data,it is concluded that there is a critical value of twist and speed,in the range of twist 400-600T/m,and when the device speed increases to 45 rpm,the device works better and the yarn performance is optimal.Compared with the traditional ring spinning,the yarn breaking strength of twist 400T/m,500T/m and 600T/m increases by 31.3%,6% and 13.6%respectively,and the 3 ㎜ hairiness was reduced by 53.5%,35.2% and 63.6% respectively.Compared to conventional ring spinning at twist levels of 300T/m-600T/m,the production efficiency of mechanically twisting spinning was increased by 44.7%,37.7%,19.4% and 17.7%respectively.The experimental results surface: the performance and production efficiency of ring spun yarns are improved by the additional twisting device.The centrifugal and frictional forces generated by the device lead to a transfer of fibers,an increase in the inter-fiber clamping force,an agglomeration of fibers at the edge of the sliver,a reduction in the width of the twisting triangle and the yarn quality is increased.The sliver gain twist in advance before they are twisted and wound,providing spinnability for low-twist yarns.At the same time,the spinning efficiency can be improved by reducing the design twist of the ring spindle at a certain spindle speed.