Key Technology Research Of Synchronous And Proportional Recovery Of Straw With No-tillage Precision Seeding And Straw-covering In Maize Stubble Fields

The 2BMFJ type no-till precision planter which applied the way of expelling straw sideways was able to integrate seedbed preparing,precision seeding,fertilization,compacting,pesticide spraying,and straws mulching equably at one operation.The planter has become an important technical mean to guarantee the combination of intensive cultivation and conversation tillage of corn,soybean and peanut.The amount of straws returning had significant effects on the grain yield and soil microorganism,in order to achieve no-tillage sowing and straws recycling at one operation,so that achieving the best amount of straws returning.This study designed a straws synchronous recovery device matching the 2BMFJ type no-till precision planter,completed the key technology research through the combination of theoretical analysis,numerical simulation,and experimental study.The main research contents and results are as follows:(1)Dynamics model of lateral straw throwing: Comprehensively considered with the influence of air resistance,soil interference and other uncontrollable factors on the spatial trajectory of the straws,the kinetics analysis of lateral throwing process of straws was taken,a model of straws lateral throwing dynamics with modified coefficients and a parametric equation of spatial trajectory of straw were established.Modified coefficient regression models are established for combine harvester harvest plots and artificial harvest plots which applied with the method of three-factor and five-level quadratic regression orthogonal center combination and a high-speed photography technology.The test result showed that the relative error between the actual displacement and theoretical value of straws were between 10.01%~14.80%,correlation coefficient were between 0.9347~0.9832.(2)Design of proportional recovery device of straws: The main structure and technical parameters of the straw recycling device were determined.The principle of adjusting the proportion of straws recovery was determined,and the design of the deflector was carried out A power model of recovery device was established.The power consumption of the recovery device was calculated as 7.032 k W.By the power of recovery device as the initial conditions,the hydraulic motor,hydraulic pump,relief valve,throttle valve type were selected through the calculation.(3)Analysis on the flow field of the straws recovery device: Through used FLUENT software,numerical simulation analyses were carried out by means of air flow recovery ofdifferent factors.Through the transient analysis method,the affect of axial blades number on the airflow was studied.The outlet flow of axial blades number from 1 to 5 were 0.310 kg/s、0.317kg/s、0.329 kg/s、0.339 kg/s、0.334 kg/s.Comprehensive comparison,axial blades number was set as 4.Through the method of steady-state analysis,the affect of blades length,blades axial overlap length and diameters of inlets on the airflow were studied.The outlet flow and blades length,blades axial overlap length,diameters of inlets are positively related.Comprehensive comparison,the blades length was set as 150 mm,the blades axial overlap length was set as 20 mm,diameters of inlets was set as 140 mm.Recovery device bench test results showed that the measured value was consistent with the distribution of the numerical simulation,simulation value was small than the measured value and the deviation was in the range of 10%.(4)Finite element analysis of critical components of recovery device: By using Workbench software,the modal analysis and prestressed modal analysis based on fluid-solid coupling method on the impeller were carried out.Prestressed in the impeller,prestressed modal ratio was low about10% than modal ratio.Impeller mode was with 12 orders as a group;the impeller external source excitation frequency was 140 Hz,the value of frequency was smaller than the twelfth order prestressed modal as 14.7 Hz,at the rotational speed of 700 r/min,the impeller did not affect the operation quality of resonance.(5)Prototype manufacture and field performance experiment: The prototype can recycle straws smoothly,by changing the installation angle of the deflector,the recovery ratio of straws can be realized,the relative error between theoretical recovery ratio and recovery rate was5.69%~9.49%,no-cleanliness rate were 6.08%~16.32%.