Abstract:Aiming at the problems of high millet agglomerates rate, high damage rate and high undelivered net loss rate in the process of mechanical harvesting, a longitudinal axial flow double flexible rolling threshing device was designed. The device adopted longitudinal axial flow threshing drum, and flexible rubber roller was installed on the threshing drum, which can reduce the damage rate of millet grain and realize the flexible and low damage threshing of millet. The rubber surface had wavy protrusion, which had good milling and threshing performance for millet. The flexible concave grate was composed of two hollow cylindrical nylon screening units, and each group of two rows of hollow cylindrical nylon screening units were mutually staggered to form U-shaped holes suitable for the separation of millet seeds. The support device of concave grate had micro motion, and the flexible micro motion concave grate was formed with the flexible concave grate, which was conducive to the separation of millet seeds and the reduction of grain rate. The feed rate, drum speed and threshing clearance were selected as the experimental factors, and the grain rate, damage rate and net undelivered loss rate were taken as the indexes to carry out the ternary quadratic regression orthogonal rotation combination test, and the optimal parameter combination of feed rate, drum speed and threshing clearance was determined. The results showed that when the feeding rate was 1.4kg/s, the roller speed was 735r/min and the concave gap was 9mm, the damage rate of millet grain was 0.35%, the millet agglomerates rate was 1.78%, and the undelivered net loss rate was 0.64%, power consumption was 10.6kW, which provided the basis for the further development of a type of millet threshing device.