Design And Experiment Of Air-absorbing Disc Type Hami Melon Precision Seed Discharger

Hami melon,is one of the most important fruits in China.With the increase of its planting area,the growth rate of Hami melon production in China has been higher than the global average.However,its low level of mechanized production has seriously restricted the development of Hami melon industry.Sowing is a vital link in Hami melon production,which directly affects the final yield of Hami melon.Aiming at the problems of poor seed filling performance and high missed sowing rate caused by inactive population of flat Hami melon seeds,based on the current situation of Hami melon cultivation in Xinjiang and the agronomic requirements of Hami melon sowing,this project developed an air-absorbing disc type Hami melon precision seed discharger with inflow slot,and the main research contents are as follows:(1)The physical parameters of Hami melon seeds were determined by physical experiments,and the triaxial size,sphericity,100-seed weight,density,moisture content,elastic modulus,shear modulus,poisson’s ratio,contact parameters and suspension speed of Hami melon seeds were obtained.The seeds were mapped by Solid Works software,and the discrete element model of Hami melon seeds was constructed.The rolling friction coefficient of Hami melon seeds was calibrated with the natural angle of repose as the index,and the static angle of repose of seeds and the dynamic inclination angle of rolling accumulation were used as the indicators to verify the accuracy of the DEM model,which provided a basis for the subsequent coupling simulation.(2)Combining the characteristics of Hami melon seeds and the agronomic requirements of sowing,an air-absorbing disc type Hami melon precision seed discharger with deflector grooves was designed,its structure and working principle were introduced,the kinetic analysis of the movement process of seeds was carried out,the mechanics model of Hami melon seed adsorption was constructed,and the structure of the seed discharger was optimized by using EDEM to determine the optimal solution.(3)The simulation model was constructed by combining discrete element theory and computational fluid dynamics,and the effect of different vacuum degrees and different rotational speeds on the pressure distribution of the internal flow field of the seed releaser was analyzed based on Fluent software.The simulation study of the seed filling process of Hami melon seeds was carried out by coupled CFD-DEM technology to analyze the effect of the size of vacuum degree and the rotational speed of the seed releaser on the seed filling situation,and the rationality of the structural design of the key components of the seed releaser is also verified.(4)An air-absorbing disc type Hami melon precision seed discharger was built,and a single-factor test and a quadratic orthogonal rotational combination test were designed to analyse the seed filling performance of the seeder,using the negative pressure of the suction hole of the seeding disc,the rotational speed of the seeding disc and the inclination angle of the seeding disc as test factors and the pass index,the misssowing index and the resowing index as test indicators.The results show that the factors influencing the pass index are rotational speed,negative suction hole pressure and inclination angle in order;the factors influencing the miss-sowing index are negative suction hole pressure,rotational speed and inclination angle in order;the factors influencing the resowing index are negative suction hole pressure,inclination angle and rotational speed in order.When the inclination angle of the seeding disc is16°,the negative pressure of the suction hole of the seeding disc is 1.15～1.84 k Pa,and the rotational speed of the seeding disc is 11.76～18.86 r/min,the qualifying index of the seeder is 93.67%,the miss-sowing index is 2.38% and the reseeding index is 3.95%,which meet the agronomic requirements of Hami melon seeding.