DESIGN AND FINITE ELEMENT ANALYSIS OF VARIABLE-DIAMETER THRESHING DRUM WITH MOVABLE RADIAL PLATES

Abstract

In view of the fact that the threshing gap of combine harvester can only be controlled by adjusting gravure screen and it is time-consuming and laboring, a kind of variable-diameter threshing drum with movable radial plates is developed by changing the diameter of threshing drum to adjust the threshing gap concentrically. All parts of the threshing drum were designed and checked by mechanical design principle, and the statics and modal analysis of the whole structure were carried out by ANSYS Workbench. The results show that the maximum deformation of the variable-diameter threshing drum with movable radial plates is 0.29 mm under boundary conditions. The maximum allowable deformation of the threshing drum in use is 3 mm, which meets the requirements of use. The equivalent stress of the threshing drum with variable diameter is up to 100 MPa, which is less than the yield strength of the material, and will not cause structural damage. According to the modal analysis, the natural frequency of the threshing drum does not cause resonance phenomenon. The field test of wheat was carried out after the processing of the variable-diameter threshing drum with movable radial plates was installed, and the working performance was compared with that of the ordinary drum. The results showed that the threshing performance was the best when the forward speed was 1 m/s, the grain entrainment loss rate was 0.53%, and the grain un-threshed rate was 0.065%. The grain breakage rate is 0.54%, and the performance is more than 50% higher than that of ordinary rollers. It lays a foundation for the adaptive adjustment of threshing gap in combine harvester.