Study On The Behavior And Influencing Factors Of Twin Screw Solid Transportation

In polymer processing,twin-screw extrusion has the characteristics of continuous production,high yield and energy saving.It has attracted much attention in polymer material blending,filling modification,alloying and functionalization,and has been widely used.In order to obtain the best quality products and extrusion output,the material transportation in the solid conveying section of the extruder is an important stage of polymer processing in the extruder.It is necessary to understand and understand the change mechanism of the material transportation.Most of the solid conveying section of the extruder moves in the barrel with solid discrete particle groups.The discrete element method is a numerical calculation method for studying the moving particle system.This method uses each particle as the analysis object in the calculation process.The movement of particles at different moments.Most of the researches on the twin screw solid transportation are carried out by visual experiments,which cannot accurately reflect the particle motion characteristics in the barrel.The application of the discrete element method to the research of the solid screw section of the twin screw extruder can overcome the problems The particle movement information that cannot be extracted can accurately reflect the particle movement law in the barrel.This paper uses discrete element software EDEM to simulate the solid conveying section of a twin-screw extruder using the discrete element method.First,the particle movement under the overflow feeding method is mainly dragged by friction,and the particle trajectory shows an “?” shape.In the space formed by the screw and barrel,the screw moves in the extrusion direction as the screw rotates.Next,the material transportation process under the metering and feeding mode is simulated.The solid conveying section under the metering and feeding mode is divided into sub-conveying areas to study the transport characteristics of each area.The particle transport in the metering and feeding mode is mainly based on positive displacement.The axial velocity and axial force obtained by the particles in the overflow feeding mode are higher than those in the metering feeding mode.In the metering feeding mode,the axial speed and the axial force of the particles and the transport efficiency of each sub-conveying area were studied by changing the screw speed,the friction coefficient in the extruder and the lead of the threaded element.It was found that increasing the speed to the left conveying The conveying efficiency of the zone and the upper conveying zone has been improved.Too high a speed will cause the conveying rate of the right conveying zone to decrease and increase the coefficient of friction in the extruder.The conveying efficiency of each conveying zone decreases.The coefficient of friction in the extruder should be reduced.Changing the lead of the threaded original in the conveying section can improve the conveying efficiency of each sub-conveying area and is relatively stable.