Study On The Mechanical Model And Mechanism Of The Composite Spinning Extrusion Process

China is the largest country of the textile production and export, and the textile products are accounted for more than35%of the world total. The textile industry planning is mentioned to the people’s livelihood level. However, there is still a gap in the technology of the differential fibre and composite fibre between china and developed western countries, which leads to the international competition ability of the product is not strong. And the final reason is weak at the related theory research. The extrusion swell mechanism of polymer melt spinning has a great effect on fiber forming and performance. Because of boundary condition, drawing rate, cooling and other factors, these make the extrusion process of component melts more complex.In the spinning process, extrusion swell plays an important role on the fiber cross section shape and size, and the micro-hole geometry size (entrance angle, length-diameter ratio, extrusion rate) affects extrusion swell ratio. Based on polymer rheology theory, the numerical simulation of non-newtonian fluid flowing process is studied. The rules of extrusion swell phenomenon of co-extrusion process are studied in different entrance angle, different length-diameter ratio and different extrusion rate. And based on Polyflow fluid dynamics simulation software, the interface changes are simulated under the different microporous structure and flow ratio.In this paper, the elastic behavior during the flow process of the melt spinning and the theoretical basis of these elastic behaviors are introduced. And mainly describes extrusion swell phenomenon. This phenomenon plays an important role on the fiber properties. Firstly, this paper derives out the velocity distribution using geometric analysis, so the composite extrusion swell ratio is obtained. Secondly, according to the characteristics of extrusion molding, based on the polymer rheology and fluid dynamics theory basis, the three-dimensional viscoelastic theory model which describes the flow of viscoelastic polymer melts is established. Combined with the fluid dynamic finite element algorithm, the co-extrusion flow conditions in the different conditions of melt spinning are simulated by Polyflow. The simulation results show that the change of the melt flow has an important effect on the extrusion section, and the micro hole geometry size effect on extrusion swell, that is, when length-diameter ratio is small, the entrance angle has a certain effect on extrusion swell, and with the microporous length-diameter ratio increases, the size of entrance angle is very not obvious to extrusion swell. The influence of entrance angle to extrusion swell gradually disappears with the increase of length-diameter ratio. With the increase of the stretching rate, the velocity gradient will increase along the extrusion direction. And when the stretching rate is too big, it can make the extrusion flow become unstable. At last, according to the spinneret design principle, we design a kind of parts of the three components for spinning components, and the flow conditions are simulated by Polyflow. The simulation results show that reduce the flow rate of the low viscosity melt and increase the flow rate of the high viscosity melt, will make the low viscosity melt flow speed decrease and the high viscosity melt flow speed increase. This can make three melt flow speed tend to be evenly, so the extrusion section has a small change.