Numerical Simulation And Experimental Research On Three-screw Plastic Granular Material Mixing

Parallel arrangement of three-screw extruder is one of the widely researched polymers mixing equipment.In order to ensure the product quality of blend extrusion,it is feasible to mix the material particles in advance in the feeding section of the threescrew extruder.scheme.The kneading block element can realize the advantage of increasing mixing,but its application research is mainly concentrated in the melting and mixing section,so in order to obtain a better blending effect,the kneading block element is used in the feeding section and the three-screw effect on material particle transportation and mixing performance is especially important.In this paper,based on the theory of discrete element method,the relevant research on the mixing process of two different material particles in a three-screw mixing device was carried out.The main research contents are as follows:Based on the particle mixing theory and the geometry of the three-screw,the contact and movement of the particles in the three-screw channel were analyzed.The model of the three-screw mixing device was created in the modeling software,and the blending of two different types of materials,polypropylene(PP)plastic particles and low-density polyethylene(PE-LD)plastic particles,in the three-screws was carried out using extended discrete element method(EDEM)discrete element software Numerical simulation research was carried out during the process.The simulation results show that the movement of particles in the three-screw is complex,and the force and speed of the particles in different sections are not consistent.Among them,the shear force on the particles in the kneading block section is the largest,and mixing effect is the most significant.The discrete element method was used to simulate and simulate,and the force and velocity changes,dispersion and mixing state,and motion trajectory of the material particles at different mixing moments were observed.Through dynamic monitoring of the particles,the mixing mechanism of the kneading block was analyzed,and the material was accurately expressed.The movement law of each particle in the threescrew barrel.The research found that convective mixing accounts for about half of the three-screw particle blending process,and the mixing effect is good;dispersion mixing accounts for about a quarter,and the mixing effect is poor;distribution mixing accounts for about a quarter,which plays an auxiliary mixing role.role.The effects of technological parameters such as screw speed,particle size,and staggered angle of kneading blocks on the mixing performance of the three-screw were studied,and the uniformity value of the two material blends under different influencing factors was calculated.After comparing the change curves,it is found that the combination of screw speed in the range of 120rpm～160rpm,particle size between1.7mm～2.2mm and kneading block screw equipped with staggered angle of 45° can effectively improve the mixing effect.A three-screw mixing device model was established,and the simulation results were analyzed and verified through experimental research.After comparison,it was found that the experimental results were basically consistent with the simulation results,which verified the reliability and accuracy of the discrete element simulation.The research results have a certain reference value for the high-quality preparation of PP modified polymer materials by triple-screw extruder.