| Panax notoginseng is a precious Chinese herbal medicine, the planting area of which has reached 0.6 million mu.In currently, the way of sowing mainly dominated by manual dibbling and lack of the matching precision seeder, which not only wastes time, but the quality of sowing is poor. Given all these, the key component of panax precision seedeer, seed metering device, was carried out to study in this paper. The air-suction roller precision metering device of Panax notoginseng was designed, which can effecitively solve the problem, such as structure complex, positive and negative exchange interfere. On the basis of experimental research on the physical properties of Panax notoginseng seed, the modeling of Panax was bulit in discrete element software. 3-D model of the precision metering device was bulit and movement of the seed was analysised. The internal flow field was simulated analysis and the structure was optimization. Through the study of prototype testing, the best working parameters was found. The specific research content as follows:(1) The physical characteristics of Panax notoginseng seeds were studied. The average diameter of Panax notogingseng is 5.62 mm and the sphericity is 90.86% indicating the Panax notoginseng seed can be approximate to sphere. The seeds density decrease linearly with the decrease of water content. As a decrease in moisture content, the angle of internal friction and the angle of repose firstly decreased and then increased to maximum value as well as the angle of sliding friction. The average floating speed decreases linearly with the decrease of water content.(2) Based on the parameters of the seed, the model was built and the angle of repose simulated. Compared with the experiment, the test measured angle is 31.5 °and the simulation data is 31.7 °,which show the error is slight and this method is practical. What’s more, adhesive Bonding of the seed model was set up in EDEM, which can adapt to the small grid computing coupling simulation.(3) Based on the principle of the hydrodynamic drag force, the four process named: suction, articles, throwing and the transition process was be analysis, calculate the required adsorption force; the basic structure of precision seed metering device and the corresponding parameters were determined, all parts 3D model was built by CATIA software, and anlaysis the interference and analysis of virtual assembly.(4) 3-D model was established by using the ANSYS ICEM CFD software, which was divided into non-structural grid. In the constant pressure boundary conditions, the k-ε model and wall function method in the Fluent for the numerical calculation of full gas flow field distribution inside the drum. The results show that, the suction hole axial number is greater than 5, as the number increases, the effect of stability of internal negative pressure is not significant. Empty mandrel and roller radius ratio is larger, the stronger adsorption force pore uniformity, showing the first increased and then decreased.(5) The experimental study of optimization of parameters on the performance of the seed metering device was analysis in self-designed. The test use three factors and five levels of the two rotating combination test method, the vacuum, seeding speed and suction angle as factors, the multiple index, miss index and quality of feed index as the objective function. Though optimize the processing of the test data with response surface method, the mathematical model was established between the factors and the objective function. Gets a set of better parameters combination of vacuum degree, seeding speed and suction angle, namely the degree of vacuum in the 660Pa ～ 720Pa, the working speed of 0.72 ～ 0.76m/s, can obtain the qualified index greater than 90.2, leakage sowing index less than 4.9, the replay index is less than 5.3.The conclusion of this parper can provide a theoretical basis for the foundation and parameters for deeply study for the air-suction roller precision metering device of Panax notoginseng. |
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