Design Of Carrot Seeder Metering Device

If the mechanized production of common vegetables can be realized,vegetable industry can improve production efficiency,reduce production costs and improve the competitiveness of Chinese vegetables in the international vegetable market.However,in the process of vegetable production,the main problem in this field is that agricultural machinery and planting measures are not matched.The study solve that integration of agricultural machinery and agronomic measures in carrot sowing link as an example.Firstly,the cultivation mode of carrot was explored,which was convenient for mechanical operation.The suitable cultivation mode of carrot was determined based on the distribution of soil aggregates,leaf growth and dry matter accumulation.Secondly,according to the requirements of suitable planting mode,a seed metering device suitable for carrot seed pellet sowing was designed by using theoretical analysis,discrete element simulation analysis,bench performance test and field test.Primary coverage:（1）Through the field experiment for two years,three planting modes were set under the condition of the same planting density,studies were that changes of soil structure and growth of carrot.The results showed that the treatment of narrow row and wide ridge could improve soil structure,increase the proportion of soil macroaggregates（particle size>1 mm）in harvest period,increase the surface soil by 84.6%,and increase the bottom soil by 145.65%.Leaf morphological peak decreased and appeared about 10 days earlier;it is conducive to inhibiting the leaf growth at the expansion stage of fleshy roots and promoting the accumulation of dry matter to the underground.The total dry matter increased by 16.4%～38.35%,the distribution ratio increased by4.62%～7.7%,and the yield increased by 1,450.5～1568.85 kg/ha.It is a new planting mode beneficial to the deep integration of agricultural machinery and agronomy.（2）We measured material parameters of pellet,and accorded to agronomic requirements,material parameters and process requirements,a carrot metering device was developed,the overall structure and working principle of the metering device are analyzed.The filling hole section is designed by using the theory of the most rapid decline curve,which effectively improves the working accuracy of the metering device.（3）According to the characteristics of pellet materials,the pellet dynamic model was established,and the discrete element software was used to conduct the virtual experiment on the seed metering performance of the seed metering device model.The simulation experiments were carried out with the rotation speed of the filling disc and the inclination of the arc beam mouth as the single factor,and the simulation experiments of rectangular,hemispherical and steepest descent line filling holes were carried out.The experimental results show that when the rotating speed of the filling disc is 32 r/min,the opening diameter of the filling hole is 5.3 mm,and the inclination angle of the arc beam is 74°,the qualified rate of grain spacing is 86.32%,and the variation rate of seed metering uniformity is 28.67%.The simulation results are better.（4）Seed metering performance optimization test,pellet sowing test and vibration adaptability test were carried out by using seed metering device performance test bench.First of all,through the single factor experiment,the influence law of the rotation speed of the filling disc,the inclination angle of the arc beam and the inclination angle of the metering on the metering performance is clarified.Secondly,the effect of each factor interaction on seed metering performance was explored by multi-factor test.Finally,the performance of seed metering device in actual field operation was predicted by vibration adaptability test.The single-factor test results showed that the influence of various factors on the test indexes was similar.With the increase of the rotation speed of the seed-filling disc,the inclination of the arc beam mouth and the inclination of the seeding row,the qualified rate of the grain spacing first increased and then decreased.The multi-factor test results showed that the optimal parameter combination was the rotation speed of the seed-filling disc30.78 r/min,the inclination angle of the arc beam mouth 44.92°and the seeding inclination angle 33.02°.At this time,the predicted values of the qualified rate of seeding spacing P1,the reseeding rate P2 and the missed seeding rate P3 were 90.03%,5.48%and 4.49%.When the working speed of the metering device was 28 r·min^-1～36 r·min^-1,the average qualified rate of seed spacing was 85.22%,which still met the agronomic requirements of carrot metering.It showed that the metering device still had good metering performance under the condition of changing the speed.The vibration adaptability test results show that the working quality of the seed metering device still meets the requirements of carrot planting when the vibration frequency is increased to 10 Hz and the vibration amplitude is increased to 10 mm,indicating that the seed metering device has good adaptability.（5）According to the agronomic requirements of carrot sowing,the metering device was used as the core component,and the ditcher,soil coating device,pressing wheel and frame mechanism were configured.The carrot seeder that completed the ditching,seeding,soil coating and pressing processes at one time was integrated.Taking carrot pellet as the test material,the field performance test was carried out with the rotational speed of seed metering device as 31 r·min^-1and the seed metering inclination angle as 45°.The qualified rate of grain spacing and variation coefficient were determined to test the sowing performance and adaptability.The results showed that the coefficient of variation of carrot seed pellet sowing uniformity ranged from 15.14%～16.33%,and the average coefficient of variation was 15.75%.The average qualified rate of seed pellet spacing was 88.90%,and the performance indexes met the agronomic requirements of carrot planting,and were better than Chinese national standards.The research results are conducive to screening out the suitable mechanical planting mode of carrot.The developed carrot seeder metering device has certain application value,which can provide a theoretical basis for the design and development of small mechanical seeder metering device.