Analysis Of Pore Group Effect And Performance Test Of Quinoa Pneumatic Precision Seed Metering

Quinoa seeds have the characteristics of irregular shape,small 1000-grain weight,rough surface and large friction coefficient etc.The seeds are greatly affected by the fluctuation of air tightness during the pneumatic precision sowing operation,which is difficult to realize precision sowing.During the experiment of metering device,it is found that not only the suction hole has the ability to absorb seeds,but also a certain number of seeds are attached around the suction hole,which is called hole group effect.The pore group distribution of different parameters has a great differences in the adsorption effect of quinoa grains,and the emergence of pore group effect has a great influence on the stability of the number of grains per hole.The emergence of this phenomenon is closely related to the airflow field inside the seed metering device.In this thesis,theoretical analysis,flow field simulation and performance test are carried out based on the mechanical and physical characteristics of quinoa seeds.The main research contents are as follows :1.The physical characteristic parameters of quinoa seeds were tested to determine the shape and size,1000-grain weight,density,friction coefficient and suspension velocity of seeds.The design of seed metering tray is carried out by using porous combination of holes,and its working principle is analyzed.The force analysis of seed adsorption process is carried out,which provides theoretical basis and reference for the structural design and simulation research of seed metering device.2.The finite element analysis software was used to simulate the internal airflow field of the seed-metering device under different parameters,and to explore the flow field distribution characteristics of the seed-metering device.Combined with the physical characteristics of seeds and the theoretical analysis results in the process of seed suction,the area where each suction hole has a stable adsorption of seeds was found,which laid the foundation for the subsequent study of accurate adsorption and the reasonable control of the number of seeds per hole.3.The seeding performance bench test was conducted based on the indoor seeding performance test bench.Taking the vacuum degree,the rotation speed of the metering plate,the number of suction holes on the suction plate and the distribution position of the suction holes as the experimental factors,the mixed orthogonal test was carried out to explore the best working condition of the metering performance index.Through the comprehensive weighted average method,it can be obtained that when the number of suction holes is 5,the distribution position of suction holes is D11,the vacuum degree is1.2 KPa,and the rotational speed is 15 r / min,the test performance is the best.