Design And Experiment Of Seed-dropping For Friction Seed-metering Device

Precision seeder is the key component to realize precision seeding,and its performance reliability determines its sowing quality.The seed movement in the seeding process of the existing seeder is easily disturbed by the field operation environment and the seeds will slip and bounce in contact with the soil,which seriously affects the sowing quality.In order to improve the quality of seeding,this paper designed a rotating seed feeding device for the friction seeder,analyzed the seed feeding process of the friction seed metering device theoretically,and simulate d the seed feeding process of the friction seed metering device by using EDEM software.The comparative verification test and multi-factor test were carried out on the seeder seeding device by using the seed metering device performance test bench and the soil trough test bed.The main contents of the research are as follows:(1)According to the principle of zero-speed seed feeding and the whole structure of the friction vertical disc seeder,the overall design scheme of the seed-feeding device was determined,and the working principle of the seed-feeding device and the seed-feeding device was expounded.Based on the analysis of force and motion,the movement model of soybean seed in the seed-feeding device was established.The variation of displacement,velocity,acceleration and normal force of soybean seed relative to seed-feeding tube with the rotation angle of seed-feeding tube was obtained.(2)According to the law of seed movement in the seed tube,the key parts of the seed feeding device were designed.The length and cross-section of the seed tube were determined by the size of the seed and the structure of the seed feeder,and the position and length of the seed nozzle were determined by the variation of the relative displacement of the seed with the rotation angle of the seed tube.Based on the motion analysis of the seeds outside the seed-feeding tube,the position and length of the cam and the initial angle of the seed-feeding switch were determined by the motion law of the seed-dropping,and the length of the seed-feeding outlet was 30 mm.The initial angle of the seed-feeding switch was 45 °and the length of the seed-feeding cam was 65 mm.(3)The EDEM discrete element software was used to simulate and analyze the working state of the seed feeding device of the friction vertical disc seeder.According to the simulation results,the effects of the rotating speed of the seeder,the friction force of seed feeding and the initial position of seed feeding on the working performance of the seeder were obtained,which provided a reference for selecting the combination of working parameters to meet the requirements of seed feeding of the seeder.It also provided a reference for the selection of the working parameters of the practical test of the subsequent seeder.The high speed camera was used to test the performance test bench of the precision seeder,and the rationality of the design was verified.The single factor verification of the working parameters and the structural parameters obtained by the simulation shows that the qualified index can reach more than 90%.It can meet the expected effect of simulation.(4)The whole factor test was carried out to test the operation performance of the plant,to seek the suitable range of the plant,and to analyze the influence of each factor on the performance index.High-speed photography system was used to analyze the seeding process and the f alling motion of the seeder,and the working performance of the seeder was explored.The results of the experiment showed that when the forward speed is 2.0m/s,seed-dropping height is 50 mm and seed spacing is 60 mm,the qualified index was 96.0%,the multiple index was 1.6%,the missing index was 2.4% and the variation coefficient was 8.4%.It can meet the requirement of precision sowing.In order to verify the accuracy of the optimal design of seed feeder based on discrete element simulation,a comparative test was carried out to verify the reliability of seed feeding performance of the seed feeder with or without friction seed feeder.