DESIGN AND EXPERIMENTAL STUDY OF A SINGLE LONGITUDINAL AXIAL FLOW THRESHING AND SEPARATION DEVICE WITH COMBINED RASP-BAR AND NAILTOOTH THRESHING ELEMENTS FOR MILLET

In response to the problems of high glume cluster rate, significant losses, and limited adaptability during millet combine harvesting in China, an independent test bench for a single longitudinal axial-flow threshing and separation device was designed and constructed. Millet moisture content, feeding rate, and threshing drum rotational speed were selected as the influencing factors, while impurity rate, glume cluster rate, and total loss rate were used as evaluation indices. Single-factor experiments and orthogonal rotational combination tests were conducted. The experimental results show that the order of influence on impurity rate, glume cluster rate, and total loss rate is: moisture content > rotational speed > feeding rate. The optimal operating parameters obtained were: moisture content of 24.82%, feeding rate of 2.25 kg/s, and drum rotational speed of 835 r/min. Under these conditions, the impurity rate reached 31.90%, the glume cluster rate was 21.56%, and the total loss rate was 0.72%. These findings provide a technical reference for the future design and development of single longitudinal axial flow threshing and separation devices specialized for millet harvesting.