| Plot breeding trial of maize in china basically use manual for sowing.The demand for special machinery on maize breeding trial is more and more urgent.Research on precision seeding equipment for maize breeding trial is a trend of the development of breeding mechanization.Aiming at the problems of low sowing efficiency,poor consistency,low mechanization,lack of special equipment and other sowing adaptability in maize breeding experimental sowing operation,the technology of accurate cyclic automation control and self-purification without mixing had been researched.a precision seeder for corn plot,which integrated component seed supply,low loss seed distribution,high purity seed cleaning and high precision seed planting had been designed.The study was shown in the following aspects.According to the agronomic requirements of different stages of breeding experiment,the overall scheme design of corn plot seeder was carried out.According to the principle that the plot length needed to be controlled accurately,the cable detection mode was adopted to control the plot length.The main structural components and the whole machine were modeled digitally by SolidWorks software.The arithmetic logic of automatic control system and the pneumatic system with cylinder was designed to realize the automatic control of cleaning and filling cycle operation between two plots.In order to meet the needs of maize breeding trial,an air-suction precision seed meter with self-clearing seed chamber had been designed,whose seed chamber and seed clearing chamber were independent of each other.The process of metering and clearing did not interfere with each other.The self-purification rate could achieve 100%.The main structural parameters of seed meter were determined.Dynamics analysis of the process of seed adsorption was carried out,and EDEM software was used to verify the disturbance of churn plate to the fewer population.Fluent software was used to simulate the seed clearing process.It was proved that when the remaining seeds were not more than 10 and the clearing time was not more than 1 s,the vacuum of clearing seeds was greater than 3 kPa,the remaining seeds could be cleared completely.Seeds used in breeding experiments were graded,single factor experiments were carried out in the vacuum range of 3-4 kPa.The results showed that seeds adsorbed on suction holes in the clearing stage could still be sown normally regardless of their specifications.The response surface optimization method was used to design the experiment.According to the results of variance analysis,response surface and contour plot,significance of the effect on performance indicators of seed-metering devices was analyzed.The order is scraping position,vacuum degree,rotational speed and suction hole diameter.Four optimum combinations of working parameters of seed meter was obtained,which provided a basis for the adjustment of working parameters of seed meter in practical operation.With the comparison trials of varieties of Anhui Long Ping High-Tech Co.,Ltd.,field experiments were carried out on the self-cleaning air-suction precision metering device.The results showed that the seedling emergence effect met the seeding requirements of the breeding trial,and there was no case of abandonment of plot trial caused by the seeder.Field experiments of corn precision plot seeder were carried out,in which the vacuum was 8 kPa,the distance between the scraper and the suction hole center was 3 mm,and the rotation speed of the metering disk was about 20 r/min.Double-grain seeding plate with suction hole diameter of 4.5mm was selected.The results showed that the single-seed rate was 6.2%,the double-seed rate was 92.45%,the multiple-seed rate was 1.25%,and the leakage rate was 0.1%.It could ensure that the rate of seedling shortage can be much lower than 10%?15%.Comparing the consistency of sowing depth,seed germination time,hollow stem rate abd yield,it was proved that the trial quality of mechanical sowing was obviously better than that of artificial sowing. |
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