Study On Kneading Blocks Configuration In Co-Rotating Twin Screw Extruder

The co-rotating twin screw extruder is widely used in polymer processing and paper making fields because of the perfect mixing effect, high output and low energy consumption. The twin screw composed orderly of many types and different number of screw elements. The extrusion process is divided into different function zones. Different materials need corresponding screw configurations. The performance of the elements and the screw configuration would be researched clearly for designing the screw configuration.The goal of this research was to explore the law and improve the mixing performance of the combination of the kneading blocks. The mixing indexes were studied in the base of experiment. The relationship between the mixing performance and different geometry, different combination, different work parameter and different intermeshing rate was researched the designing rules.The translation problem between the screw elements with different sections was studied in the first part of this paper in the base of the twin screw geometry. A kind translation groupware was designed which would be used flexibly.In this paper, two indexes were used to estimate the mixing ability of the kneading blocks in the base of analyzing the mixing evaluation indexes of the kneading blocks. The one was the mean shear stress which would estimate the dispersive mixing ability. And the other was the mean reflux index which would evaluate the distributing mixing ability. In this paper, the relationship between geometry parameters and mixing ability was studied with the kneading blocks. And a regression model was established which would estimate the mixing ability by the geometry parameters of the kneading blocks. A perfect dispersive mixing configuration and a good distribution mixing configuration were found in base of that the mixing effect of configuration kneading blocks of different geometry parameters were researched. A regression model was established which would guide to design the screw configurations. At last, the effect of the process conditions for the mixing ability was studied and a regression model established which would guide to adjust the operating condition.Some rules of kneading blocks combination have been found in this research. There is reference value of the rules for the screw configuration design.