Optimization Design And Research Of Spinning Box For Melt-blown Equipment

Method of melt-blown nonwoven fabric belongs to a kind of non-woven fabrics,which are widely used in composite materials,sound-absorbing materials,filtration materials,heat preservation material,health supplies,oil absorption material and clean cloth,battery diaphragm,etc.,have a huge market demand,and melt-blown fabric production in China,though large,melt-blown equipment has a basic implementation localization,but spinning box,spinneret,such as the core components of production,There is still a certain gap with foreign first-class manufacturers,so this paper for meltblown spinning box design optimization and research.Firstly,in order to improve the performance of melt distribution evenly in the spinning box of melt-blown equipment,and take into account the requirements of manufacturing technology and cost of the spinning box cavity system,a flat-slit flow channel design method using rectangular section hanger manifold was proposed.Based on the Carreau-Yasuda viscosity model,the carreau-Yasuda viscosity model guarantees the generality of design methods at lower or higher fluid shear rates,while introducing the concept of characteristic distance and shape factors to replace diverging manifolds with rectangular-section manifolds with constant depth.The optimization of flow channel structure in spinning box was achieved from the point of production.The simulation results with CFD software PolyFlow show that the flow channel of spinning box designed by this method can obtain more uniform melt outlet velocity in the whole width range,and meet the design goal of spinning box cavity.Then,in order to improve the uniformity of melt flow velocity at the outlet width direction and reduce the melt pressure drop inside the spinning box,the parameters of manifold depth,melt inlet size and slit thickness of the spinning box flow channel were optimized by using the genetic algorithm NSGA-ii based on the non-dominated rapid sorting algorithm.Finally,a better solution of the structural parameters is obtained in pareto frontier of the optimization solution set.During the process,the improved electrical network method was used to replace the PolyFlow software fluid simulation to quickly obtain the rough flow rate distribution of the melt in the spinning box.The results show that the pressure drop of internal melt is reduced by 4.16Mpa and the maximum deviation rate of outlet flow rate is reduced by 0.68%,which are better than the previous design scheme based on experience.Finally,the fluid-structure coupling analysis of the melt flow in the spinning box is carried out by ANSYS Workbench platform,which provides reference for the external structure design of the spinning box.The results of unidirectional fluidstructure coupling analysis of the spinning box with thickness of 160 mm,200 mm and 240 mm show that the deformation at the exit of the spinning box along the width direction is nonlinear,the maximum deformation of the spinning box always occurs in the middle of the exit,and the increase of the thickness of the box has a significant effect on reducing the deformation at the exit.The bidirectional fluid-structure coupling analysis of a 200 mm thick spinning box shows that the deformation of the flow channel of the spinning box causes the change of melt velocity distribution at different positions at the exit,and the flow velocity near the symmetrical surface of the spinning box increases obviously.