Design And Experiment Of Precision Air-suction Cell-wheel Seed Metering Device For Panax Notoginseng

Panax notoginseng is a kind of precious medicinal material,which is mainly grown in Yunnan Province.With the increasing medical value of Panax notoginseng,the demand for Panax notoginseng in domestic and overseas markets is increasing which shows a rapid development tendency.According to the characteristics and agronomic requirements of Panax notoginseng,the row spacing and plant spacing of the seedlings of Panax notoginseng are only 50 mm.In order to achieve high-density precision seeding of Panax notoginseng,we designed a precision air-suction cell-wheel seed metering device.Based on mechanical-pneumatic seed filling technology,the seed metering wheel has water drop-shaped holes on both sides,which could operate in a way of “one-wheel seeding double-row and multi-wheel in series”.This paper carried out the design and experiment of precision air-suction cell-wheel seed metering device for Panax notoginseng.The main research contents and conclusions are as follows:(1)Using reverse engineering technology,based on bonded particle model,the seed particle model of Panax notoginseng was established in EDEM software to test and calibrate the contact parameters between Panax notoginseng seed particle model and ABS plastics by comparing bench tests.(2)Based on the theory of fluid mechanics,the flow field type in the metering device was determined and the mechanical model of the seed adsorbing process was established.The air suction process was studied and analyzed.The adsorbing performance of Panax notoginseng seeds was studied by bench test to obtain the relationship between the adsorbing distance of Panax notoginseng seeds and sucking hole pressure which provide a theoretical basis for the design of the precision air-suction cell-wheel seed metering device.(3)Based on the characteristics of Panax notoginseng and the agronomic requirements of planting,a precision air-suction cell-wheel seed metering device was designed.The overall structure of the metering device was determined by three-dimensional modeling with UG software.The main structure parameters of seed metering device are determined by theoretical calculation and empirical formula.(4)Based on EDEM,the simulation test of mechanical filling performance was carried out.Based on FLUENT,the flow field simulation tests of negative pressure chamber,positive pressure chamber and air separator of seed metering were finally carried out.(5)Through bench test,the optimum working parameters of seed metering device were determined.Three-factor quadratic regression orthogonal rotation combination experiment was carried out with negative pressure of sucking hole,rotation speed of seed metering wheel and height of seed layer as test factors,and qualified index,missing index,multiple index and variation coefficient of each row displacement consistency as test indexes.Experimental results show that the sequence of qualified index is negative pressure of sucking hole,rotation speed of seed metering wheel and height of seed layer.Based on the results of examination,we found that the fitting of the equations was good,when the height of seed layer reaches 50 mm,rotation speed of seed metering wheel spins at 34-48 r/min and negative pressure of sucking hole between 560~660 Pa,and under the optimal condition,the qualified index is greater than 93.0%,the missing index was less than 3.5%,the multiple index is less than 3.5% and variation coefficient of each row displacement consistency is less than 3.0%.The precision air-suction cell-wheel seed metering device meets the standard and requirements by comparing the results with the national standard and Panax notoginseng planting requirements.This approach of research is suitable for the exploitation of Panax notoginseng seed-metering device.