Design And Experimental Research Of Small-size Vegetable Seeds Air Suction Precision Seeder

China’s vegetable production and consumption ranks the first in the world,and vegetable planting industry is the second largest crop industry in China.However,the special physical characteristics of vegetable seeds,such as small particle size,easy damage and light weight,seriously restrict the development of vegetable mechanized seeding technology.The mechanization of vegetable production in China is still in the initial mechanization stage.The mechanized seeding of vegetables in most areas is less than 15%,and the development level is low and uneven.There are many key technical problems to be solved in vegetable seeding.Aiming at small particle size of vegetables in gas suction seed metering device of poor universality,complex structure,low qualification rate of problem,put forward the small particle size of vegetable seed suction type precision metering technology and equipment research,aims to develop a precise seeding,high universality and seeding quality gas suction precise metering device,simplify the structure of transmission system and the whole machine,double planting operation efficiency.The main research contents of this paper are as follows:(1)The physical parameters for 1000-grain weight,water content,resting angle,sliding friction angle,particle size distribution and density of Suzhou green,Shanghai green,Chinese cabbage,fast food,chicken hair vegetables,Chinese small cabbag six vegetable seeds with typical small grain size were determined.These parameters provide theoretical basis for mechanical analysis of seeding process,mold hole size design,FLUENT and EDEM simulation analysis;(2)An innovative air-suction precision seed metering device for small-size vegetable seeds was proposed based on the double-disc structure with variable grain size.The double-disk structure with rotatable combination and variable hole diameter was adopted.The disc was provided with four types of holes of different sizes,and precision sowing of seeds with different grain size could be achieved without replacing the disc.Metering mechanism study of gas suction seed,establish a kind of absorption,with kinds of seeds in the adsorption pressure and metering plate diameter,aperture,the mathematical model of working parameters such as structure,the stress analysis of seed and verification,in the row of kind of seeds from type hole weight metering mechanics analysis,and determined the trajectory equation of the metering device for parameter optimization and provide theoretical basis for structure design;(3)Using EDEM software to obtain the stacking distribution state of the seeds at each time point when they enter the seed box,the movement rule of the seeds in the seeder under the influence of seed disturbance and the overall movement trend of the population,and verify the rationality of the structure design;Using the FLUENT software to influence factors such as pressure,angle of the shaped hole has carried on the simulation analysis,single factor flow in proven type different hole shape on the flow field of gas chamber,the influence of flow rate and considering the pressure status of force bearing analysis on the seeds,and ultimately determine the best type hole is 60 ° taper angle type hole,optimum operation conditions for speed 34.37 r/min,4.10 kPa pressure value;(4)The seed arrangement performance of the developed precision seed arranger was tested and studied.The single-factor experiment of structural parameters and working parameters was conducted by using the JPS-12 test bed.The orthogonal factor experiment was conducted considering the interaction between various experimental factors to obtain the structure and working parameters of the seed arranger under the optimal working state.Field experiments were conducted to verify and analyze the field experiments.The results showed that the seedlings had good growth effects,and the stability variation coefficient of total sowing displacement,consistency variation coefficient of each row’s displacement,missed sowing rate and average qualification rate all conform to the requirements of qualified indexes.The seeder conform to the agronomic requirements of agricultural machinery.