Abstract:The threshing cylinder of the crawler-type grain combine harvester tends to become easily clogged under high feeding rate conditions, which leads to severe fragmentation of threshed materials, resulting in an accumulation of residuals on the cleaning screen, which affects grain sieving efficiency, increases cleaning losses, and significantly elevates power consumption. By optimizing the structure and arrangement of the rasp bars and threshing elements, a spiral interlaced arrangement threshing cylinder was designed. This design reduced fluctuations in cylinder load and decreased the impact intensity of the threshing elements on the material, thereby minimizing material breakage and fragmentation. Through discrete element simulation and bench tests, the distribution patterns of threshed grain were analyzed. A comparative analysis was conducted on the migration speed of stalks within the original cylinder and the designed cylinder, as well as the torque exerted on the cylinder. The simulation results indicated that at rotational speed of 750 r/ min, the migration speed of stalks within the designed cylinder was increased by 23.5% , facilitating the rearward conveyance of materials. Additionally, the average torque of the designed cylinder was decreased by 29.2% , with reduced torque fluctuations, thereby improving the stability of the threshing operation. Field comparison test results showed that the designed cylinder significantly reduced stalk breakage and fragmentation, thereby decreasing the load on the cleaning screen and increasing the probability of grain passing through the vibrating screen. The cleaning loss rate was reduced by an average of 22.8% . Moreover, under the same operating conditions, the combine harvester equipped with the designed cylinder demonstrated an average fuel consumption reduction of 18.1% . Combining the results of the simulation experiments and field comparison tests, it was evident that the designed threshing cylinder can reduce operational losses, enhance working efficiency, and lower threshing power consumption. It effectively met the requirements for low-loss, high-efficiency operation under high feeding rate conditions.
