| As the first major oilseed crop in Anhui Province,rape is mainly distributed along the rivers and rivers of the region,where rainfall is abundant and the soil is clayey,rape is susceptible to water damage at different times of its growth as a crop with a water-limited root system.In order to address the problems of poor operational stability of the existing rape direct seeding machine,poor drainage of the rapeseed beds and high planting costs due to the need for manual reshaping of the rapeseed beds after sowing,a through-row preparation device is designed based on the principle of extrusion and its working principle is described.The study is based on the principle of extrusion moulding,the design and principle of operation of the through-row furrow preparation device,and the application of mass point dynamics theory,discrete element numerical simulation and experimental verification.The main findings of the study are as follows:(1)Parameter calibration of typical clay loam simulation model in rice oil rotation area was studied based on discrete element software nonlinear elastoplastic model.According to the sensitivity test,four parameters,including tangential stiffness factor,soil particle collision recovery coefficient,surface energy and static friction coefficient,have great influence on soil subsidence.Box-Behnken test design method was applied to determine the order of contribution to soil subsidence from large to small,which was soil particle collision recovery coefficient,static friction coefficient between soil particles,surface energy and tangential stiffness factor.A quadratic polynomial regression model of soil subsidence and the above parameters was established,and the actual subsidence obtained from physical tests was taken as the target value.The above parameters were optimized,and the optimal combination of calibration parameters was obtained: the inter-particle collision recovery coefficient was 0.477,the inter-particle static friction coefficient was0.309,the surface energy was 5.97,and the tangential stiffness factor was 0.674.(2)The structural design and parametric analysis of the border trench preparation device were carried out.A mechanical model of the soil extrusion process between the bed trench preparation device and the soil was established,the conditions affecting the stability of the trench shape were clarified,the key structural parameters of the bed trench preparation device were analysed and determined using mass dynamics theory,and the range of key factors affecting the performance of the device in opening the bed trench was clarified: the angle of entry into the soil was 25°-35°,the initial metric angle was 25°-45°,the maximum metric angle was 40°-60°,when the tilt angle of the side plate was 70°-85°,the angle of the wing plate was 5°-20°,70°～85° and the wing plate clamping angle 5°～20°.(3)Numerical simulations of key structural parameters were carried out and their effects on furrowing performance were analysed.By establishing a discrete element simulation model,tests were carried out on the structural parameters of the curved body of the furrow preparation unit and traction resistance.The results showed that the test factors of entry angle,initial element line angle and maximum element line angle have a significant influence on the traction resistance of the plough body.The results show that the tilting angle of the side plate and the angle of the wing plate have a significant influence on the integrity of the furrow,and the mathematical model for optimising the structural parameters of the furrow preparation device is constructed,and the integrity of the furrow is 73.5% when the tilting angle of the side plate is 70° and the angle of the wing plate is20°.(4)Field performance tests were carried out to verify the performance.Simulation tests were carried out on the simplified model of the unit for rototilling and furrowing,and the data extracted was analysed and processed in conjunction with software image processing.The results showed that the designed furrow preparation unit had a furrow integrity of73.5%,a furrow width stability factor of 94.73% and a furrow depth stability factor of96.27%.The results showed that the integrity of the trench shape was 78.69%,the stability coefficient of the trench width was 97.13% and the stability coefficient of the trench depth was 92.52%,and the error between the simulation test and the field test was less than 6.6%,indicating the feasibility of the simulation model.The stability coefficients of trench width and trench depth of the field test bed trench preparation device are greater than 80%,which meet the requirements of the national standard. |
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