Rotor Profiles Evolutionary Design And Evaluation Of Mixing Performance For Intermeshing Co-rotating Twin-Screw Kneader

Co-rotating twin-screw kneader is widely used in the food industry, chemical industry, rubber industry and so on, because of its advantages in material transport, mixing and plasticizing ability. Screw rotors, as the core components of extrusion mixing system of twin-screw kneader, its configuration has a direct effect on the shearing, stretching, mixing on the processing material and physical properties of extrusion product.This paper focuses on the study of profiles design method for rotor profiles of co-rotating twin-screw kneader. The application of envelope principle method on the rotor profiles design of intermeshing co-rotating twin-screw kneader, has resolved the defects of relative motion method, and get rid of the district of conventional co-rotating profiles generating method and its conventional profiles including curves. Also the profiles design ideas for unconventional rotor profiles is expanded. Circular end cross-section profiles method, based on envelop method, is proposed. Using the relative motion method and envelop principle method, profiles evolutional design with changing relative design parameters, is showed respectively. Also combined with functional theory, a new approach of rotor profiles design for co-rotating kneader rotors is studied. In the last part, numerical simulation is applied to study the mixing performance of the conventional double-flighted screw rotors and novel rotors generated by the new method. Detailed works are as follows:(1) Background and significance of the research are discussed, and an overview of the development and research status in domestic and foreign is researched. And rotor profiles design status is described.(2) The study begin with the basic geometry of conventional screw rotor profiles and perfect the derivation process of profiles generating process by relative motion method, and point out the district of this method. Envelope principle is also applied for the profiles design, according to the characteristic of the pairs of circular and its conjugated lines, a novel method generating profiles that including only circular arcs is proposed. Using the relative motion method and the novel method respectively, lots of rotor profiles are evolved from the given initial cross-section rotor profiles with changing relative design parameters.(3) The functional theory is used to the design of rotor end cross-section profiles, and composing teeth curves which is scroll curves expressed by Taylor series and its conjugate envelop lines is also researched; The position of circular center, radius and different rotating speed of the special scroll curves expressed by Taylor series—circular line, is researched. According to the characteristic of rotor profiles and Fourier series, changing the relative parameters of Taylor series, six typical types of end cross-section profiles expressed by Fourier series is obtained and their evolutional relationship is researched.(4) The formulas of geometric characteristics of screw rotors, including the rotor helical surface, axial cross-sectional shape, meshing line and area utilization coefficient are researched. The influence of meshing line and area utilization coefficient on the working performance is studied.(5) Numerical simulation is applied to study the mixing performance of conventional double-flighted screw rotors and three other rotors generated with the profiles obtained by the new method, comparing the parameters including residence time distribution, segregation scale, shear rate, stretching rate and so on which indicating the mixing performance to evaluation the mixing performance of the four screw rotors.