Study On Extrusion Process Of Planetary Plasticizing System

Planetary screw extruder was becoming applied more and more widelybecause of its advantages such as high yield, efficient and excellentplasticizing and mixing properties. However, so far there is little researchabout its extrusion process theory. An experimental platform of planetaryscrew extruder was set up to study the extrusion process including theoreticalanalysis, experiment research and simulation of planetary screw extruder wasresearched,Conveying mechanism, minimum residence time, output, and plasticizingmechanism of planetary screw extruder were analyzed in this thesis.Conveying mechanism of material in planetary section could be divided intopositive conveying、drag conveying and pressure conveying. Axial velocity ofpositive conveying was also studied. Based on the conveying mechanism, theformula of minimum residence time was deduced; influencing factors and theeffecting trend of minimum residence time were analyzed too. Similarly, flowrate of section full of material can be divided into displacement flow rate,pressure flow rate and sticky drag flow rate. Influencing factors and theeffecting trend were also analyzed on these flow rates. According to the movement and form of material, plasticizing of material in planetary sectionwas studied. Plasticizing mechanisms in different sections included heattransfer, frictional dissipation, plastic deformation, viscous dissipation anddissipative mixing melting, of which the most important factor is heatconduction.On the basis of theoretical analysis, systematic experiments were carriedout on a self-designed planetary screw extruder, which contained verificationtests of theoretical analysis, experiments about effects of processingparameters (feeding screw speed and main screw speed) and structuralparameters (die diameter and number of planetary screw) on processingproperties (head pressure, meld temperature, the minimum residence time andpower dissipation). Experimental study on change of output after adjustingprocessing parameters was discussed in this thesis too. According to theexperimental results, we found that analysis accord with experimental results.Combined with theoretical analysis, experimental investigations to analyze thespecific way and reason of these effects were carried out too.Finally, Simulation of planetary section full of material was carried outby employing POLYFLOW, and distribution of pressure, velocity and shearrate were obtained.