The Plasticizing-Mixing Theory Of Tapered Differdntial Twin Screw Machine

The quality of the productions was directly determined by the plasticizingand mixing quality of the polymer during processing process. Thecompression property in the longitudinal direction of the screw of taperedscrew extruder as well as the tensile compression property in the crossdirection of the screw of differential twin screw extruder are all have areinforcement effect on the plasticizing-mixing field. The tapered differentialtwin screw mixing extruder was invented by combining the properties of theabove two machines. The research and design of the tapered differentialtwin-screw mixing machine was on the basis of the research of conicaltwin-screw extruder and differential double screw kneading machine.（1）Tapered screw extruder: As the single-screw extrusion theory is theresearch foundation of the single-screw extruder. The extrusion theory of theflat screw that with the groove depth shallow gradually and the tapered screwwas deduced and analysed. It was found that in the solid transportation sectionof the screw, The capacity of pressure building and the output of theproduction increased and the power consumption decreased because of theexisting of the cone angle. The length of the melting section also decreased as for the existing of the cone angle.（2）Differential twin screw extruder: Because of the speed differencebetween the two rotors of the differential twin screw kneader, From the crosssection of the screw we could see that, When the two rotors rotated, They havea strong tensile and compression effect on the polymer materials that is veryhelpful for the plasticization and mixing process. The flow field simulation ofthe differential twin screw kneader was carried out in this part. The simulationresults showed that: The mixing effect of the end face decreased as the ratiodifference increased. The longitudinal mixing ability and self cleaning abilityof the differential twin screw kneader that with a speed ratio of5:1are muchbetter than the kneader that with a speed ratio of4:1and3:1.（3）Characterization research: Whether in the vertical compression ofthe tapered screw or in the tensile compression of the cross section of thedifferential screw, They all have close relationship with the pressure field.Because of the good performance of the ultrasound in polymer detection, Theinfluence of pressure on the melting as well as the solidification process of thepolymer was characterized by the ultrasound. The following conclusions wereobtained from the experiments: The melting as well as the solidificationprocess of the polymer can be characterized by the amplitude and the velocityof the ultrasound wave, And the influence of the pressure on the melting andthe solidification process can also be reflected.（4）The design part: The conical differential twin screw kneader wasobtained by combining the advantages of the conical twin screw extruder andthe differential twin screw kneader. The design of the screw components and kneading plate of the conical differential twin screw kneader was introducedbriefly.