Study On Seed Conveying System Of Sunflower Combined Harvester

4ZXRKS-4 self-propelled sunflower combine harvester uses the combination of spiral conveying and pneumatic conveying to transport sunflower seeds.Pneumatic conveying has the characteristics of simple structure,high conveying efficiency,closed and environmentally friendly conveying process,and small area.The main power source of pneumatic conveying is blower.After threshing by threshing device,the grain is transported to the pneumatic conveying pipeline by screw conveyor,and the wind generated by the fan blows the grain to the grain collection box.At present,the machines often have problems such as pipeline blockage,high energy consumption,grain breakage and low productivity.Therefore,the mechanism of spiral conveying and pneumatic conveying is studied to find out the causes of blockage and low productivity.The relevant parameters of the conveying system were optimized to improve the working efficiency of the harvester,reduce the blockage rate and grain breakage rate.The main research contents are as follows:(1)The physical parameters of sunflower seeds including density,Poisson ’ s ratio,angle of repose and shear modulus were measured by physical test and simulation test.Contact parameters include static friction coefficient and collision recovery coefficient between sunflower seeds and sunflower seeds;parameter range of friction coefficient and collision recovery coefficient between sunflower seed and geometry.The three-dimensional size of sunflower seeds was measured and the three-dimensional simulation model of sunflower seeds was established.The corresponding parameter ranges were obtained through physical experiments,and the optimal simulation parameters were determined by combining with EDEM simulation experiments,which provided parameter support for gas-solid coupling simulation experiments.(2)The mechanism of sunflower seed conveyor was analyzed to preliminarily find out the reasons for low production efficiency and blockage.The parameters affecting the conveying efficiency of the conveying system are derived by formula,and the relevant parameters of the conveying system are calculated according to the productivity of the harvester.The factors causing the problems were determined through the gas-solid coupling simulation test,and the guide plate was designed to eliminate the gas loss and increase the air volume in the system.Different bendingdiameter ratios were designed to reveal the effects of airflow velocity,gas pressure,grain movement velocity,grain distribution and wall wear.Compared with the original machine and the new machine,the conveying efficiency of the new machine is increased by 19.5 %.(3)Based on the simulation results,the test bench was designed and processed for comparative verification test.The accuracy of the simulation parameters and the reliability of the simulation results are verified by comparing the internal airflow velocity and conveying efficiency of the conveying system.