| Recently,in order to balance the production of corn and soybeans on limited land,China has gradually explored a series of rotation techniques that were suitable for Northeast China.Amongst these,corn-soybean rotation attracted much of the attention as a rising and promising rotation technique.In a typical cycle of the corn-soybean rotation,the corn was planted for the first two years with another one year planting of the soybean.The advantages of the corn-soybean rotation included the soil moisture retaining and conserving,the reduction of wind-water erosion,the high corrosion of the stubble degradation,the increase of the organic content in soil,et al.In the planting of the soybean,some problems arose from the residual of lodging maize straw and stubble on the earth surface.The maize straw and stubble would easily block ditching equipments,increasing the difficulty of stubble-breaking.The precision seed arrangement problem of soybean is to solve during sowing.The seed dropping would easily occur due to the shake of the seeding apparatus when the tractor wheels and machineries were exposed to the maize straw and stubble on the earth surface during the operation.Thereby,the conventional soybean planters seemed to be unsuitable for the corn-soybean rotation.It was significative to deeply study the precision planting technique for corn-soybean rotation.The development of an appropriate soybean planter for corn-soybean rotation.Focusing on the design of soybean planter for corn-soybean rotation,the present study detailedly investigated the geometric forms,structural parameters,the relationship between the operation mode and operation effect of the critical components of the machinery.The study was consisted of the theoretical analysis,the experimental design,the construction of mathematical models,and the simulation analysis,et al.The regular patterns had been summarized and quantified.The critical components of the seed discharging,stubble breaking,and earth repressing were legitimately designed.Firstly,we had designed an anti-blocking device for the soybean till-planter to appropriately work in the situation of the residual of lodging maize straw and stubble on the earth surface in the process of corn-soybean rotation.The designed device had a blade combined structure with the advantages of low power consumption and high straw cutting rate.The process of the straw cutting had been investigated via the methods of theoretical modeling and kinematics analysis.The optimal curve of the side cutting edge of straw cutting blade was established to be an equal slip angle curve.Through the orthogonal test of three factors and three levels,it was found that the optimal parameters of the straw sliding blade were 2.1 m/s for the operating speed,35 mm for the tillage depth,and 185 mm for the blade radius of gyration.The straw cutting rate and the power consumption of single blade had been established to be 90.9% and 8.15 W via the experimental results.Secondly,a biased double disc air suction metering device for the soybean till-planter had been designed.The principles of the seed extraction and the seed discharging were analyzed,and the critical components of the device were optimized.The single factor test and the general quadric rotation test had been carried out by using the rotating speed of the seeding sucker and the velocity of the airflow as test factors,and the rate of seed missing as test index.The optimal factors were established to be 220 m/s of the airflow velocity,100 r/min of the rotating speed of seeding sucker on the basis of the simulating model of the Design-Expert software.The rate of seed missing was calculated to be 2.72%.Thirdly,a hydraulic control friction wheel transmission device had been designed.The radial dimensions and the reasonable choice of the transmission tyres were established by the theoretical analysis.The relationship between the tire pressure,the deformation and the loading could be obtained on the basis of the analysis of the friction wheel transmission device.The three-dimensional model of the whole component was formed on the basis of the kinematics simulation analysis of Adams simulation software.The maximal friction tire pressure value for the transmission was calculated to be 25.9 psi.Based on the field trial results of the transmission effect of the friction wheel transmission device,the slip rate curve of the friction wheel was formed by changing the measured tire revolutions and moving distances of the friction tires and the comparison of the slip rate of friction wheel under different tire pressures.The optimal value of the tire pressure for best transmission effect of the friction wheel was calculated to be 24.345 psi.Fourthly,in order to resolve the problems of the uneven soil compaction and the long longitudinal dimension of the till-planter,we designed a copying elastic press roller with the elastic spoke structure.Based on the results of the theoretical analysis,the major structural parameters such as 450 mm of the diameter,210 mm of the width,and 12 of the elastic spoke value for the repression roll had been established.In summary,we had successfully designed the 2BDG-6 soybean till-planter.The results of the field trial revealed 86.8% of the grain spacing conformity index,5.2% of the leakage index,93.75% of the qualification rate of seeding depth,and only 0.3% of the seed crushing rate under 6 km/h of the working speed.All the performance indexes of the machines exceeded the requirements of the relevant national standards.The designed planter could play an important role in the promotion of corn-soybean rotation in Northeast China... |
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