Discrete Element Analysis And Performance Test Of Pneumatic Precision Metering Device For Quinoa

Aiming at the problems of poor seeding stability,suction hole clogging,and injury of small-sized seeds during the operation of the pneumatic seed metering device,with quinoa seed as the research object,a seeding plate was designed with spoon seeds function,and obtains the force of quinoa particles in the seeding process through theoretical analysis;Discrete element simulation method was used to explore the influence of different seed spoon structure parameters on population migration and seed filling effect.Based on the above research,combined with bench test,the effect of different working parameters on seeding performance was investigated.The main results of this study are as follows:1.According to the D'Alembert's principle and other related theories,the seed tray(including seeds taken plate,body of seed tray and sheet sucking the seed),suction chamber and seed chamber were designed by the analysis of the force condition of the scoop up seed,seed in absorbing,seed in clearing,seed in carrying and seed in throwing process.2.With quinoa seed as the research object,the physical parameters of the quinoa are measured to obtain the shape,density,angle of repose,friction coefficient and recovery coefficient of the seed,and in order to determine the quinoa discrete element simulation parameters,based on the particle accumulation test,the simulation parameters of quinoa grain simulation are calibrated by Design Expert software design test.The Poisson ratio,density,Young's modulus,static friction coefficient,rolling friction coefficient and collision recovery coefficient of seed and contact material(PLA)were determined.3.According to the analysis of discrete element software,it is found that the movement of quinoa population can be divided into rising area,static area,collapse area and reflux area under the rotation of the seed spoon,which shows that the scoop disturbance to the population is significant.Through EDEM software for different seed spoon structure parameters of the seeding disk simulation,and seed speed and number of seeds per scoop simulation analysis,to obtain the round center angle of the seed spoon between 30 to 60 degrees,the scoop position angle between-15 to 15 degrees can meet the work requirements of the seed metering device.4.According to the results of variance analysis of seed metering device performance,the result of obtaining the round center angle of the seed spoon and the seed tray speed had a significant effect on the quality index of seeds number per hold and quality index of holes distance,the round center angle of the seed spoon had a significant effect on the variation coefficient of holes distance,and none of the factors had a significant effect on the index empty holes.5.Due to the different optimal operating conditions of the seeding performance indicators,through the method of comprehensive weighted scoring to unify the dimensional of each indicator,the better operating parameters of the typer are the round center angle of the seed spoon 45 degrees,the scoop position angle 0 degrees,the typing shaft speed 15 r/min,under this condition,the number of quality index of seeds number per hold is 90.3%,the quality index of holes distance is 91.0%,the index empty holes is 0.7%,the variation coefficient of holes distance is 7.0%,to meet the requirements of small grain size crop seeding.