| Welsh onion is one of the important economic crops in China,and its planting area and output rank first in the world.The shallot seedling cultivation is the most important link in the shallot production.There are two main ways of seedling cultivation of shallots: one is the traditional artificial seedling,and the other is the special mechanical seedling.At present,the cultivation of scallions mainly depends on manual labor,with high labor intensity,poor emergence quality,and low mechanization,which is not conducive to subsequent mechanized transplanting.Although there are some general vegetable seedling raising machines on the market,the lack of special plant seedling raising machines for coating green onion seeds and other general seedling raising machines have poor applicability and reliability,serious clogging,and high missed replay rate.The agronomic requirements of one-hole,three-grain planting,especially when the seeding speed is too fast,results in a high rate of missed seeding,which leads to subsequent mechanized transplantation requiring artificial seedling replenishment,which is time-consuming and labor-intensive.Therefore,the hysteresis of the spring onion seedlings has seriously hampered the development of the whole process of the production of green onions.The research contents of this paper include: investigating the agronomic requirements of green onion planting,and measuring the physical characteristics of coated green onion seeds.The precision seeding device of the core components of the plug-onion onion seedling planter was studied.The mechanical seed metering device and the air suction seed metering device are combined to achieve a high degree of coupling between the airflow field and the gravity field,so as to improve the seeding qualification rate of the precision seeding device.The kinematics analysis of the seed metering and other processes is carried out,and the seed metering device is designed based on this.Use three-dimensional design software SolidWorks to design and analyze each component.Based on the existing seed meter,a socket-type drum seed meter is prepared,and parameters such as socket shape,depth,arrangement,roller diameter,and rotational speed are determined.Using EDEM software Discrete element analysis was performed to establish the seeder dynamics model,and the seeding process was simulated.The effects of different speeds and different socket shapes on the yield rate were analyzed through simulation.The flow field of the seeder was simulated and optimized by Fluent software Use CAD software to draw processing drawings of the final parts,make a precision seeding device test bench,and verify the design effect of parts assembly according to the overall plan.The sowing performance test was performed on the precision seeding device.The singlefactor test was performed with the pass rate,missed rate,and replay rate as the performance indicators,and the inclination angle of the sockets and sockets,the vacuum of the air chamber,and the speed of the seeder.Obtain its reasonable working parameter range,and carry out threefactor three-level quadratic regression orthogonal test.Based on the test data results,a response surface mathematical model is established using Design-expert software,and the mathematical model is optimized.The model optimization results show that when Eye tilt is 13.1°,seeder rotation speed is 9.91 r / min,and air chamber vacuum is 3.14 kPa.The best seeding effect is achieved;the average missed rate of 5 tests is 2.524%,and the average replay rate is 1.132%.The average pass rate is 96.344%,which is consistent with the optimization results and better than the agricultural industry standards. |
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