Analysis and performance test on dynamic seed corn threshing and conveying process with variable diameter and spacing

In order to further reduce the damage rate in threshing seed corn, a seed corn threshing testbed with variable diameter and spacing that can realize dynamic adjustment of parameters, such as feed quantity, rotating speed of the threshing device, threshing spacing of the threshing units, was designed in this research. The software of finite element analysis ANSYS Workbench was applied to do modal analysis on the threshing axis designed for variable diameter and spacing of seed corn. The first 8 orders of natural frequencies were distributed in 201.12-1640.20 Hz, with corresponding vibration amplitude in 5.86-27.04 mm, showing reasonable structural design of the threshing axis, which could realize effective seed corn threshing and conveying. Discrete element method was applied to do simulation analysis on the seed corn threshing and conveying process with variable diameter and spacing. Under the condition of different feed quantity, different rotating speed of the thresher, the moving speed of corn clusters and contact force among clusters were measured through simulation, and the working characteristics of the threshing testbed for low-damage and dynamic threshing and conveying of seed corn with variable diameter and spacing were revealed. Working performance test results of the testbed of seed corn with variable diameter and spacing showed that, when the rotating speed of the threshing axis was 190-290 r/min, feed quantity was 1.80-3.80 kg/s, the damage rate of seed corn was 0.32%-0.63%, threshing rate was 99.20%-99.82%, and content impurity rate was 4.23%-5.86%, the mass of threshed corn grains first increased and then decreased along the axial direction. The test verification process was in line with the simulation results; thus, the test results could satisfy the requirements in design and actual operation.