The Design And Experimental Research On The Air-suction Roller Precision Seed-metering Device Of Wheat

Wheat seed precision sowing technology is the method proposed by Academician Yu Songlie,which is more than 10%higher than that of traditional wheat planting.Wheat seed precision sowing demands definitized row spacing,and the traditional wheat seed-metering devices are mainly outer trough wheel.In this paper,we designed the air-suction roller precision metering device of wheat,based on the analysis of the structure and operation principle of the existing mechanical and air-blast precision metering device,and analyzed the flow field and the working field state of the device by simulation,than researched the air-suction roller precision metering device of wheat using the combination of theory and experiment method.The main research content and conclusions are as follows:(1)Based on the agronomic requirements of wheat seed precision sowing,this paper studied the physical characteristics of wheat seed length,width,height,1000-grain weight and sphericity of Jingdong 22,and developed the air-suction roller precision metering device in order to precision sowing.We designed the key components and elaborated the operation principle,and analyzed the stress of the seed in the seed selection process.Finally,we established a three-dimensional model of the air-suction roller precision metering device used the software Creo.(2)Based on the computational fluid dynamics,the flow field analysis of the well model was carried out in Fluent software.The flow field corresponding to different factors which are suction hole diameter,suction chamber vacuum and seed roller speed was analyzed.The results showed that with the increase of the diameter of the suction hole,the negative pressure decreases,the air velocity decreases and the adsorption capacity decreases.When the negative pressure fan provided a stable pressure,the fan only affected on the size of the flow field and the flow velocity,no longer on the distribution of the flow field in the suction chamber.The simulation results are verified by the bench test.The results showed that there are some differences between the simulation results and the experimental results,but the change trend of the two is consistent,which proves that the simulation results can be used as reference.(3)Based on the discrete element method,using discrete element simulation software EDEM to establish three-dimensional models of wheat seed,simulating the seeding process of the seeder.The simulation results showed the seed generated and fell into the sucking area,and closing to the surface of the seed roller surface first moved by the friction force,some seeds fell into the nest with the row of drum rotation until out of the nest.The simulation results showed the relationship between the seed velocities,forced and time,all seeds and contacted seeds,all seeds and the friction force with time.(4)The wheat seed sowing test bed was designed and constructed by using the 3D printing technology.The bench test that the air-suction roller precision metering device of wheat chose suction hole diameter,suction chamber vacuum and seed roller speed as the influencing factors,repeated rapping rate,leakage seed,pass rate,rapping yield and standard deviation coefficient as the evaluation indices to conduct a single factor test and variance analysis of every factors,obtained the significance of different influencing factors on the evaluation index.The experiment showed that under the condition of the suction chamber was 3500Pa,the suction hole diameter was 1.6mm,and the seeding drum speed was 40r/min,the seed pass rate is highest,achieved 90.2%.