Study Of Mechanisms And Properties In Series Disc-Screw Extruder

In the resent years, because of the unique kneading characters, more and more series disc-screw extruders were used in the polymer mixing process. The work includes three aspects, such as mechanism of the series disc-screw extruder, serialization prototype development and applications. Based on the development of the CPJ75-135 series disc-screw extruder, the design principle, kneading mechanism, three-dimensional flow field simulation in the discs, quantitative analysis of kneading performance of disc, performance test and application research of the prototype are studied.Aimed at the international trend, the seven functions of series disc-screw extruder, such as conveying, melting, kneading, develatilization and metering are analyzed comprehensively by use of systematic engineering design principle. Meanwhile, the overall design method of series disc-screw extruder is suggested. CPJ75-135 series disc-screw extruder particular in our country which possesses powerful break-up, kneader and plasticating capabilities is successfully developed.By investigating the melting, mixing and flow mechanisms of series disc-screw extruder, the flow and mixing characters of the common discs and screw elements in the series disc-screw extruder were studied using a polyflow finite element software package. Mesh superposition technique (MST) was introduced to model series disc-screw extruder without calling upon remeshing. The distributions of the velocity, pressure and viscosity in the gap between revolving and stationary discs have been acquired by POLYFLOW software.Based on the statistical treatment of the flow trajectories, the mixing properties in series disc-screw extruder were studied from three respects, such as distributive mixing, dispersive mixing and axial mixing. Segregation scale and time-avarage transient efficient were used to characterized distributive mixing, mixing index was used to represent dispersive mixing and residence time distribution was used to symbol axial mixing. At the same time, the effects of disc configuration parameters and operational conditions on the flow field and mixing have been analyzed.There are outstanding mechanichemical effect because high shear in disc domain. It was verified by devulcanized experiment.The extrusion characteristics, kneading capabilities, mechanichemical properties of the equipment are discussed by experiments. The experimental study indicates that the gap between discs has the decisive effect on the output, power and unit consumption. The increasing of screw speed and the reduction of gap between a pair discs are benefit to mixing.All the preliminary investigations can provide not only theoretical basis for application and serial development of this type equipment, but also important reference for the study on kneading technology and theory in related discriplines.