Design And Examination Of Longitudinal Axial Flow Threshing Separation System Of Small-scale Harvester For Rice Crops

Abstract:Rice harvested mechanically mainly in recent years.Compared with transverse flow harvester,longitudinal axial flow feeding combine-harvester is widely used because of its better performance.Market models are mainly composed of large machines whose feeding amount is more than 2.0,which is difficult to adapt to harvest small plots in Chinese southern hilly area.Besides,the threshing time of small machine is short,due to the limitation of the length of the threshing cylinder,which causes big loss rate.Based on a large amount of literature,the study introduced the research status at home and abroad of threshing separation system of longitudinal axial flow harvester,analyzed the advantages and limitations of various devices,and discussed the elastic threshing way and the development trend of its operation equipment.As the field area is small in southern hilly,large-scale harvesters can’t pass through easily and small-scale harvesters cause big loss rate.To solve the above problem,the flexible threshing rice method is employed,and the 41z-1.6 type full feeding rice combine harvester is designed.To realize the rice threshing separation process,a small threshing separation system of vertical axis flow rice combine harvester is designed.Using the software of the Design-Expert to analyze test results of the threshing separation system.The single factor test and multiple factors quadratic orthogonal rotation combination test on loss rate of rice are conducted.Through the analysis of variance of model and quadratic regression model fitting,the secondary multivariate regression equation on loss rate of rice towards three independent variables was gained,the influence level of the three independent variables on the loss rate of rice are conducting bar spiral Angle,concave plate screen straight Angle,elastic threshing pole tooth tooth trace in a descending order.Response surface method is used to analyze the influence of the three factors on loss rate of rice.The optimal parameter combination of the system was gained as follow when the loss rate of rice is the lowest:tooth trace space of flexible threshing pole tooth is 90 mm,helix angle of conducting bar is 23 °,dip angle of vertical bar of concave plate screen is 14 °;and the loss rate of rice is 1.51%as predicted by software.The difference between actual loss rate of rice found by validation experiments and the predicted value by software is 0.12%,which means actual test value basically agree with the predicted one.Besides,it conforms to agronomic requirements of machine-harvesting which demands loss rate of rice should be less than 3%.At last,4LZ-1.6 full-feeding combine harvester was assembled with the threshing separation system whose tooth trace space of flexible threshing pole tooth is 90 mm,helix angle of conducting bar is 23 °,dip angle of vertical bar of concave plate screen is 14 °.The 4LZ-1.6 full-feeding combine harvester which manufactured in Yiyang zijiang combine harvester development company has obtained subsidies of the ministry of agriculture.It can be sold and promoted across the country.