Design and performance analysis of tangential-axial flow threshing device for oat harvester

Aiming at the problems of stalks winding and poor threshing performance in the process of mechanical harvesting of oats,a type of threshing and crushing experimental device was designed.The device was composed of a belt conveyor,a tangential-flow threshing drum,an axial-flow threshing drum,a high-speed camera and a testing device.According to a regression orthogonal test method,using the rotation speed of the axial-flow drum,the horizontal center distance,and the vertical height difference of the two threshing drums as experimental factors;using the mass fraction of long stalks and the threshing rate as experimental indexes,a mathematical regression model of factors and indexes was established,and combined parameters were analyzed for the threshing quality and crushing ability.Experimental results showed that this device had the best crushing performance when the rotation speed of the axial-flow drum was 850 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 10 mm,and this device had optimal threshing performance when the rotation speed of the axial-flow drum was 760 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 20 mm.The parameters were optimized by Design-Expert 11 to obtain an optimization result that the rotation speed of the axial-flow drum was 800 r/min,the horizontal center distance was 820 mm,and the vertical height difference was 10 mm.A verification experiment was carried out by using a high-speed camera,and the two groups of parameters were selected for a comparative experiment.Images of material movement between the two threshing drums were captured by the high-speed camera.Experimental results showed that the optimized parameters were beneficial to improving the threshing performance and anti-winding performance of the oat threshing process.This study provides a technical basis for the research and development of oat combine harvesters.

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.

Motion simulation and test on threshed grains in tapered threshing and transmission device for plot wheat breeding based on CFD-DEM

Mechanization of field experiments is the only way to improve crop breeding and seed propagation effects.In order to further clarify and improve the working performance of tapered threshing device for plot breeding,and reduce the remaining seeds in the device,the numerical simulation was carried out on the motion process of materials in the longitudinal-axial tapered cylinder threshing and transmission device of the plot wheat breeding combine harvester based on CFD-DEM method.Simulation results showed that,threshing and transmission of particles and short stalks at axial direction could be realized under the influence of air flow.Meanwhile,the material transference and distribution rule and stream field distribution rule of air flow in the threshing and transmission device were obtained,the variations of velocity and displacement of particles and short stalks with time were obtained;the motion trajectories and forms of particles in different types of retention were also studied.At rotating speed of 1300-1600 r/min for the tapered threshing cylinder in the verification test,the particle retention rate in the enclosure was 0-0.13%,while in the simulation the particle retention rate in the enclosure was 0-0.11%,only a 0.02%difference between them.The results proved a favorable feasibility to simulate the working performance of the tapered threshing and transmission device for plot breeding through gas-solid coupling method.