| In the corn-soybean rotation no-tillage planting mode,during the double-row sowing operation on the soybean ridge,because the corn root-soil combination is large and unevenly distributed in the ridge direction,the stubble cutter and fertilizer shovel of the soybean no-tillage planter can only cut and disturb the root-soil combination vertically along the forward direction of the unit,and the root-soil combination under the surface still gathers greatly,which hinders the furrow opener from moving in the ridge direction,thus failing to meet the requirements of sowing depth uniformity and row spacing consistency.Therefore,in order to solve the problem of the furrowing quality caused by the corn root-soil combination under the surface,comprehensive theoretical analysis,material physical property measurement,EDEM simulation,multi-objective optimization,response surface analysis,high-speed camera shooting,field test and other methods and means,the structural parameters of zigzag opener were determined,and discrete element simulation performance test was carried out.The field performance was compared and analyzed,and the field operation parameters were optimized and its applicability was verified,so as to provide a new reference for improving the sowing quality of double-row planter on no-tillage soybean ridge.The main research contents are as follows:(1)Design of structural parameters of zigzag openerOn the basis of expounding the structure and working principle of zigzag opener for double-row seeding on soybean ridge,the curve of front blade mouth is designed,and the curve equation of front blade is derived The mechanical model of side cutting root system is analyzed,and it is determined that the side cutting edge is zigzag.Taking the measurement results of sliding friction angle in each area of corn root-soil combination as abscissa and sliding cutting angle as ordinate,the tooth profile curve of side edge is obtained by Matlab software.according to theoretical calculation,when the tooth number of each side edge is 3,it has obvious sawing effect;According to the agronomic requirements of soybean sowing,it is clear that the seed guide tubes in the main body of the opener are arranged in a staggered manner,and at the same time,it is determined that the entry clearance angle of the zigzag opener is 5°.(2)Discrete element simulation performance test based on EDEM softwareIn order to verify the rationality of the design idea and test the performance of the zigzag opener,the simulation performance test of the designed zigzag opener was carried out by using the discrete element software EDEM.According to the material characteristics,the agricultural requirements of previous crops and the size of zigzag opener,the northeast loam-stubble-straw discrete element model was established,and the geometric model of stubble cutter-fertilizer shovel-zigzag opener was constructed by Solidworks.Finally,the overall action model was constructed in EDEM software.The results of discrete element simulation performance test show that the zigzag opener can effectively cut off the root system,and its working resistance becomes more stable with the increase of working speed,which indicates that the zigzag opener has stable working performance.(3)Comparative test of field operation performance of zigzag openerIn order to analyze the comprehensive field operation performance of the zigzag opener,under the condition of the furrow depth of 50 mm,the forward speed of the unit was set at 5 km/h,6 km/h,7 km/h,8 km/h and 9 km/h respectively,and the coefficient of variation of furrow depth,coefficient of variation of transverse grain distance and soil disturbance area were selected as evaluation indexes,and the field operation performance was compared with that of the double-disc furrow opener.The experimental results showed that the average coefficient of variation of furrow depth and the average transverse seed spacing decreased by 43.33%and 60.81%,respectively.The average soil disturbance area of the zigzag opener was 377.28 mm~2smaller than that of the double-disk furrow opener,and the zigzag opener met the agronomic requirements of double-row sowing on no-tillage soybean ridge.(4)Optimization test of field operation parameters of zigzag openerIn order to explore the best field operation parameters of zigzag opener and verify its rationality,the orthogonal rotation combination experiment of quadratic regression with three factors and five levels was carried out with the advancing speed of the unit,the depth of furrow opener and the amount of straw cover as experimental factors,and the coefficient of variation of furrow depth,the coefficient of variation of transverse grain distance,the working resistance and the cutting rate of root system as evaluation indexes.The experimental data were processed and analyzed by Design-Expert 6.0.10 software.It was found that when the advancing speed of the unit was 5.81 km/h,the furrow depth was 34.05 mm,and the straw coverage was 0.6 kg/m~2,the zigzag opener had the best operation performance.Under the best operation parameters,the coefficient of variation of ditching depth,the coefficient of variation of transverse grain distance and the working resistance were 6%,2.61%and 229.38 N,respectively.The optimized operation parameters were rounded,and the field verification test was carried out with the advancing speed of the unit 6 km/h,the furrow depth 35 mm,and the straw coverage 0.6 kg/m~2.The results of high-speed camera measurement show that the zigzag opener mainly cuts through the designed side blade.The verification test results show that the average trenching depth stability of the zigzag opener is higher than the industry minimum standard by 17.9%,the average broken soil rate after trenching is higher than the industry minimum standard by 6%,the average qualified index of grain spacing is higher than the industry minimum standard by 7%,and the average root cutting rate is 96.5%,which meets the industry standard.Simulation test and field test show that the zigzag opener meets the agronomic requirements of double-row sowing on no-tillage soybean ridge,and provides a new reference for improving the sowing quality of double-row sowing machine on no-tillage soybean ridge. |
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