Mathematical model of material kinematics in an axial threshing unit

This paper presents a study of the movement of vegetal material through the threshing space of an axial threshing unit. The developed kinematical equations are based on a nonlinear law governing the non-uniform movement of the material on an uneven helical path between the rotor and concave-cage. These equations describe: the characteristics of material trajectory (length, angle, pitch length, and number of material revolutions) as functions of longitudinal position along the rotor; the components of material velocity. The model was validated with experimental data from a large database obtained from laboratory testing. The model can be used for practical analysis of material movement influence on threshing unit performance in terms of grain separation and damage, as well as for threshing unit design and process optimization. The kinematics model proved to be highly significant and useful for predictions. (c) 2007 Elsevier B.V. All rights reserved.