Experimental Study on the Particle Size and Weight Distribution of the Threshed Mixture in Corn Combine Harvester

The distribution of the threshed mixture is the link between the threshing and cleaning process during corn harvesting. Uneven distribution leads to a local accumulation of the mixture in the cleaning, resulting in high impurity and loss rate. Existing studies rarely concern the distribution of the corn threshed mixture. To address this problem, the distribution experiment was conducted in a self-made corn longitudinal axial threshing system to explore the distribution pattern, and both the particle size distribution and weight distribution of components (corn kernel, corn cob, and corn husk) were analyzed in this study. The results showed that the drum speed and concave clearance has a significant effect on particle size. Moreover, the impurities (corn cob, corn husk) increase with the drum speed. The weight distribution has an obvious uneven trend. In the axial weight distribution, corn kernels increased initially and decreased afterwards, while corn cobs and corn husks constantly increased. In the radial weight distribution, corn kernels and corn cobs were greater on both sides and less in the middle; corn husks had a clear left posterior accumulation. The increase in drum speed and feed rate and the decrease in concave clearance aggravated the inhomogeneity of the weight distribution. By analyzing the distribution characteristics, the drum speed of 400 r/min, concave clearance of 40 mm, and feed rate of 7 kg/s were confirmed to be optimal operating parameters. Under these conditions, the accumulation of the threshed mixture was weakened, which provided a satisfactory base for the subsequent cleaning. This study could provide a data support for the improvement of the threshing system. Additionally, this study is believed to have the potential to be used for the structural design of the cleaning system to reduce mixture accumulation and improve the cleaning performance.