Design And Experimental Study Of Pneumatic Super Rice Precision Direct Seeding Device

China has a vast territory and a wide area of rice cultivation,but the degree of mechanization of rice is still very low.Precision hole direct seeding of rice seeds is the direct and uniform sowing of rice seeds in the field through machinery,which has the advantages of high operational efficiency,precise sowing quantity,and strong lodging resistance.The core technology of mechanized precision hole live streaming is the orderly single granulation and single granulation state maintenance of the population,namely precision seeding technology and seed smooth migration technology.The existing precision hole direct seeding technology for rice generally uses 6-8 grains to form holes,while super rice requires sowing per hole due to its high price and seedling rate.The pneumatic drum precision seed metering device can achieve 1-3 seed metering,but it is generally used for factory seedling cultivation.However,there is also a lack of seed guides in the existing seed guide methods that can maintain the orderly and stable movement of super rice precision.Based on the above current situation,this project designs a pneumatic super rice precision hole direct seeding guide that can be suitable for pneumatic drum metering devices,achieving stable seed guide and seeding after precision metering.The main research content and conclusions of this article are as follows:1)The material characteristics of super rice seeds were measured and the parameters of the seed discrete element model were calibrated.Establish four types of seed discrete element models,compare the experimental values of the cylinder method and the drum method through EDEM simulation,analyze the discrete element simulation results based on seed stacking and fluidity,and obtain the optimal seed discrete element model.2)This paper expounds the working principle of the pneumatic super rice precision hole direct seeding device,and carries out kinematics analysis of the force on the seeds at different stages.Conduct force analysis on a single seed when it leaves the seeder and enters the inoculation tube,derive the motion equation of the seed after leaving the seeder,and analyze the relationship between the seed motion during the above process and the rotation speed,radius,and positive pressure of the seeder;Conduct force analysis on a single seed when transported in a seed transport tube,and obtain the relationship between the motion state of the seed when suspended in the seed transport tube and gas velocity,seed velocity,and seed rotation angular velocity.3)Carry out the overall structural design of the pneumatic seed guide and optimize the configuration of key parameters through CFD-DEM gas-solid two-phase flow simulation.Orthogonal experiments were conducted at the throat,and full factor experiments were conducted on the seed delivery tube to determine the optimal structural configuration based on the time error and coefficient of variation of seed delivery.The optimal configuration was as follows: the diameter of the inoculation tube was 25 mm,the diameter of the seed delivery tube was 35 mm,the inclination angle of the inoculation tube was 45 °,the seed delivery height was 275 mm,and the bend diameter ratio of the 90 °bend was 3:1,We have established an analytical relationship between seed transport distance and seed speed,and calculated and designed the horizontal curved parts of seed guide pipes with different seed transport widths.4)Conduct two-phase flow simulation research throughout the entire process of seed guidance,revealing the impact of different operating parameters on seed guidance performance.Single factor and orthogonal experiments were conducted through two-phase flow simulation to obtain the influence of gas velocity,number of single seed guides,and seeding speed on the qualification rate and coefficient of variation of seed guides.When the gas speed is 30m/s,the number of single seed guides is 1,and the seeding speed is 5 clusters/second,the seed guide device has the best seeding effect.At this time,the qualification rate is 99.43%,and the coefficient of variation is 4.21%.5)Cooperate with the seed metering device to conduct experimental research on the seed guide device,conduct full factor experiments,and compare with simulation values to obtain the impact of air speed and seed metering speed on the qualification rate.When the air speed is 30m/s and the seed metering speed is 5 clusters/s,the qualification rate of the seed guide device is 88.29%,and the qualification rate of the seed sowing with the seed metering device is 76.29%.