| The millet planting mode is mainly based on artificial seeding and mechanical seeding in China.Aiming at its poor seeding quality,seed damage,serious waste,high cost and low efficiency of manually remove excess seedlings.Studying of the flow field pressure and velocity distribution of the air-suction seeder and the dynamics and kinematics of millet,and designing of a low-damage,free-seedling,high-efficiency air-suction precision seed metering device has become an urgent problem to be solved in millet sowing.This paper summarizes and analyzes the current research situation of precision seeding technology and equipment at home and abroad,combined with market research,summarizes the advantages and disadvantages of different types of seed metering devices,and determines the research goal of the project is the air-suction millet precision hill seed metering device.The physical properties of Zhangzagu No.5 were measured.Based on the working principle and physical characteristics of the seed suction device,a digital prototype of the seed collector and a simplified model of the flow field area were established.FLUENT simulation analysis of the influence of five factors including the fan interface position,negative pressure value of the air chamber,suction-hole number,diameter and length on the pressure and velocity changes in the flow field of the seed meter.The pressure of each end face of the physical prototype of the seed metering device was measured using a digital differential pressure gauge,which proved the reliability of the simulation results.Through the analysis of seed dynamics and kinematics characteristics during the operation of the seed metering device,the structural parameters of the seed metering disk,air chamber body and seed guide device were determined.The stress analysis at the seed filling stage showed that the factors affecting the seed adsorption capacity included the material characteristics of the seed,the structure and size of the seed suction hole,the seed filling distance and the negative pressure of the air chamber.Using the seeding test bench,a single factor test of the influence of the four factors of fan interface position,air chamber negative pressure value,hole diameter and seed shaft speed on the performance of the seed meter was carried out,the better parameters of each factor were obtained,and the little effect of the position of the fan interface on the performance of the seed meter were determined.Through the range analysis and variance analysis of the three-factor three-level orthogonal test results,the primary and secondary order and significance of the influence of the three factors of the negative pressure value of the air chamber,the diameter of the hole and the rotation speed of the seeding shaft on the seeding device are obtained.These results determined the best working parameters of the seed meter:the negative pressure value of the air chamber was-0.8 kPa,the diameter of the hole was 1.0 mm,the rotation speed of the seeding shaft was 17r/min.Under these conditions,the right rate of seeds per hill was 83.33%,the right rate of hill distance was 93.33%,the rate of damaged seeds was 0.37%,and the variation coefficient of hill distance was 5.95%. |
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