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R. Sikora, E. Sasimowski


The kinematic models of the screw-based plasticating system – comparison in rectangular coordinate frame


Polimery 1999, No 9, 600


DOI: dx.doi.org/10.14314/polimery.1999.600


Summary

Of the models used so far to describe the kinematics of the screw-based plasticating system, the two models — one with the revolving screw and the other with the revolving cylinder — were treated as equivalent and having no differences. A comparative computational analysis was carried out between these models. Suitable equations were derived and an appropriate verification performed. The equations derived to analyze the drag (or re-drag in the case of the revolving screw) flow, pressure flow, leakage flow, and longitudinal flow allowed to demonstrate differences between the two models. Differences were found to occur between the maximum values in the distribution of longitudinal flow velocities in the screw channel, about 11% between the maximum values, and between the total volume flow rates, 19.1%. The differences occur mainly on account of the peripheral velocities of the cylinder and of the screw and hence different shear rates are applied to the polymer in the screw channel, and thus different polymer viscosities occour. Further studies intended to define the power required in either of the models and to establish transverse flow rates appear worthwhile.


Keywords: screw-based plasticating system, kinematic model with either a revolving screw or a revolving cylinder, computational verification of differences between the models

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