Development Of A Guiding-groove Precision Metering Device For High Speed Planting Of Soybean

Aiming at the problem that the seed arching at the filling mouth of the mechanical precision metering device hinders the high-speed operation of the auxiliary device for seed filling and cleaning,this paper designs a high-speed precision metering device with seed guide slot,aiming at improving the efficiency of seed filling and simplifying the cleaning process,and controlling the arrangement of seeds before and after the process of seed filling and cleaning The design scheme and structural parameters of key components of the metering device were determined by means of discrete element simulation,high-speed photography technology,bench test and field test,which provided technical support for the development of mechanical soybean metering device suitable for high-speed field operation.The main research contents and conclusions are as follows:（1）The structure design of high speed precision metering seed metering device for soybean with seed guide groove.Combined with the requirements of soybean planting agronomy,a high-speed precision seed metering device with seed guide groove was designed based on the design idea of controlling the arrangement of seeds before and after filling and clearing.By establishing the mathematical model of seed filling and cleaning process,the key factors which affecting seed filling and seed cleaning process of seed metering device were determined to be the width of inner groove-wheel（L）,cone angle of the shell（δ）,the width of guiding-groove（L₁）,and the angle of the groove bottom surface to the horizontal plane（?）.（2）Simulation and experimental study on the working process of soybean high speed precision metering device.Based on the response surface method,the multi factor simulation test scheme was designed.Through the variance analysis of the test results,the regression equation between the structural parameters and the seeding performance index was established.Combined with the boundary conditions,the regression variance was optimized,and the optimal combination of structural parameters was obtained:L=8.1 mm、?=8.3°、L₁=25.3 mm、δ=23.6°。（3）The performance test of the high speed precision metering seed metering device for soybean with seed guide groove.The seed metering device was shot in different working conditions by high speed photography technology.The variation of seed feeding angle and pass rate of seed spacing was studied according to the test data.The results of bench test showed that when the advance speed of seeder was 8～15 km/h（the working speed of the seed metering device was 88.9～166.7 RPM）,the qualified rate of seed arrangement is higher than 93%,the coefficient of variation of plant distance variation coefficient was less than 22%,and all performance indexes of seed metering device meet the industry requirements of soybean precision sowing.（4）Improvement of seed metering device and field experiment of soybean with high speed precision metering.The storage space was increased to improve the stability of seed metering device;According to the size characteristics of soybean seeds,the spatial structure parameters range of seed storage was determined.Based on the response surface method,the combination test of the center was designed.The optimal combination of spatial structure parameters of seed storage was as follows:the width of seed storage space was L₂=9.4 mm,the length L₃=9.1 mm,the height L₄=4.2 mm,the height of control track Q=5.5 mm;The results show that the qualified rate of the seed spacing is higher than86%and the variation coefficient of the seed spacing is lower than 27%when the operating speed of the seeder is 4～12 km/h,which meets the national standard.