| The magnetic precision seeding relies on magnetic force of magnetic seeding element to suck covered seed with magnetic,and the magnetic force has the direct relation to the magnetic induction intensity of magnetic seeding element in the seeding space,In order to improve the efficiency,the complex magnetic system is consisted by many magnetic seeding elements which are arranged by the form of the circumference uniform and the axial array in the drum.In this magnetic structure,the different structure and combinations of seeding element will affect the magnetic distribution of the seeding spaces and the magnetic force of seeding element,furthermore,the performance of seeder will be affected.In order to improve the performance of seeding element,electromagnetic field finite element method is utilized to study the magnetic force and magnetic field characteristics of a single seeding element,and the spatial magnetic field characteristics of magnetic structure.Through electromagnetic finite element analysis of magnetic field distribution along the axial and the radial of a single magnetic seeding element given the end diameter of 2.5mm,the magnetic distribution of seeding element end face which is low magnetic field in the middle of end face and higher magnetic field in the edge of end face is gained,because of magnetic congregate effect in the edge of end face.Therefore, minimize mostly end diameter of seeding element when sowing the certain diameter seeds in order to avoid reseeding.The model is picked which higher energy utilization from four kinds of different types of structure models which are composed with open-circuit type of the original seeding element and closure magnetic shield by analyzing magnetic field.The structural parameters of picked model are optimized as follows:2 mm end-diameter,5 mm the central diameter,and 1.5 mm gap width for magnetic shield through the model test.After analysis and testing,the end face magnetic induction intensity of the optimized model is higher than original model under the condition of the same coil turns and current.The arrangement way for magnetic seeding element is attained by analysis the effect of two polar arrangement of many seeding element on the magnetic field distribution.Analyzing the factors impacted the magnetic field distribution,it shows non-uniform magnetic distribution that the magnetic induction intensity is stronger in the middle than both ends because of the influence between seeding elements and thus a method was put forward to increase the uniformity of the magnetic field by increasing coil turns of the seeding element at the both ends.The coil turns relationship between middle and both ends seeding element is got by using curve fitting.Finally,the sucking seed test of seeding element and performance test of magnetic structure shows that the spatial magnetic non-uniform of optimized structure is reduced by 50%and the performance of seeding is increased by10.7%.Based on the magnetic field characteristics of the magnetic precision seeder and experimental research,the laws of magnetic field distribution of magnetic precision seeder are gained and magnetic structure is optimized.All above can offer a reference for enhancing the performance of precision seeder,and lay the foundation of practical applications for the magnetic precision seeder in the field of small seeds mechanized precision seeding. |
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