Design And Experiment Of Air Suction Soybean High Speed And Precision Seed Metering Device

With the improvement of agricultural machinery development requirements,seeding in quality,speed and other requirements are getting higher and higher.In terms of high speed precision seeding performance,it has been studied and applied more and more widely.The working performance of the seed platter is the key factor affecting the seeding performance.Because of the advantages of no injury to seeds,relatively low requirements on seed shape and more suitable for high speed conditions,pneumatic seed metering device has been studied by many experts and scholars for many years,and the problems related to the application of pneumatic seed metering are optimized and solved continuously.This paper focuses on the problems of high pressure dependence and low seed filling rate of air suction seed planter of pneumatic seed planter under high speed condition.According to the experimental research and analysis,a kind of high speed and precise seed planter of soybean with air suction type is designed.(1)Three kinds of soybean seeds,Heihe 43,Jiyu 99 and Jiyu 302,were selected and measured for their 1000-seed weight,density,water content and other physical characteristics.In order to meet the design requirements of the suction hole of the seed plate,the outer contour information of the seed was studied and analyzed.Creo software was used to draw the three-dimensional contour size of soybean seeds,and API particle substitution method was used to bond the soybean seed replacement model.(2)According to the physical characteristics and simulation analysis of soybean seeds,the seed platter,vacuum chamber,the mechanism of seed cleaning and the structure of seed chamber were designed.The related mechanical and mathematical relationship models were established for each working part,and the seed filling,seed clearing,seed transporting and seed arranging process of the seed platter was theoretically analyzed.(3)Simulation test analysis mainly includes EDEM,CFD and EDEM-CFD.The parameters of mechanical properties of soybean seeds were calibrated by simulation test,and the calibration values of dynamic coefficient,static coefficient of friction and collision recovery coefficient were 0.03,0.43 and 0.39.The dynamic and static friction coefficients and collision recovery coefficients of soybean model established by substitution method were 0.025,0.42 and 0.37;The calibration values of the simulated static friction coefficients between seed and seed plate modeled by particle filling method and particle replacement method were 0.21 and 0.23.The fluid simulation analysis showed that the annular chamber had better flow field characteristics.When the number of suction holes reached 50,the pressure stability and size of the vacuum chamber decreased obviously.The seed filling simulation test without negative pressure showed that the seed filling performance was better at low speed,and the seed filling rate decreased rapidly with the increase of speed.(4)Based on the performance test bench of JPS-12 seed platter developed by Heilongjiang Agricultural Machinery Engineering Research Institute,a performance test bench was built for the seed platter designed in this paper.Using the test bench,the performance of the seed platter,such as seed filling and seed platter under different test factors were tested.