Structure Optimization And Experimental Study Of The Core-drawing Opener

Reducing soil disturbance and avoiding mixing of wet and dry soil during fertilization,sowing and trenching can effectively reduce the evaporation of soil moisture and ensure seed germination.The opener is a key working part of the sowing and fertilizing machine,and its structural design will have an important influence on the up and down movement of the soil and the lateral pushing under medium and high speed operation conditions.In this paper,the traditional core-opening opener is improved and designed.Using discrete element simulation and soil trough test,combined with tracer method to study the microscopic movement of the soil after the trenching operation,determine the optimal structural parameters,and conducted a comparative test.The main research contents and conclusions are as follows:(1)Core-type opener profile structure improvement.Based on the analysis of soil movement in trenching process and in-depth study of openers at home and abroad,we improved the design of the core-convex surface and changed the concave surface into a convex surface to reduce the lateral throwing of soil by open trenches;combined with sowing agronomical requirements and core opening Gutter design requirements determine the basic structural parameters and range of core-type openers.(2)Establishment of soil discrete element simulation model in Guan zhong Plain.The granular structure of the soil in the Guanzhong Plain is mainly granular.The soil of the experimental field of the School of Mechanical and Electrical Engineering of Northwest A&F University was selected.The subject group was used to determine the soil properties of the cultivated layer,and reference was made to the relevant literature data to determine the soil particle structure and soil model parameters to establish a discrete element soil simulation model.(3)Discrete element simulation analysis.Selecting the width of the opener,the angle of chamfering,the corner of the soil,the radius of curvature of the ridge,and the working speed are experimental factors.Two groups of four factors and three levels of orthogonal test are designed.The test results show that the width of the opener has significant influence on the test index.The larger the width,the larger the width of the trench,the higher the soil disturbance rate,the greater the distance of lateral soil throw,and the lower the backfill rate.According to the results of the simulation test,the parameters of the optimal core-type opener were determined to be the width B 60 mm,the chamfer angle γ 60°,the soil entering angle α 25°,and the ridge curvature radius R 300 mm.The surface layer,shallow layer,middle layer,and deep layer soil were set up to observe the microscopic movement of the soil.The optimal parameter combination and similar parameter opener was less disturbed by the backfill layer under the 8km/h operation.(4)Soil trough verification test.The angles of opener chamfering,angle of entrainment,radius of curvature of ridges and working speed were selected as experimental factors.Two groups of three factors and three levels of orthogonal test were designed.The experimental results show that the operating speed has significant effects on soil disturbance rate,ditch backfill rate,and lateral throwing distance of the experimental indicators,and the changes are-4.6% to 15.4%,26.7% to 8.1%,and 12.8% to 44.2%,respectively.According to the test results,the optimum design parameter combination of the miter angle γ 60°,the soil angle α 25°,the ridge curvature radius R 300 mm,and the optimal parameters of the soil microscopic motion analysis core-type opener are consistent with the results of the soil trough test.The difference between the simulation test and the soil trough test index width at 5km/h and 8km/h is-22.5%~-2.8% and-14.3%~5.6%,respectively;the lateral distance of the test target is 5km/h and 8km.The difference in /h was 5.7% to 30.2% and-11.1% to 5.7%,respectively.The error of the simulation test and soil trough test index is small,indicating that the simulation model is reliable.(5)Improved core-type openers compared to conventional openers.The results show that under the conditions of 5km/h and 8km/h,the soil disturbance rate of the improved core-type opener is lower than that of the traditional opener by 6% and 16.2%,and the backfill rate of the ditch is increased by 17.1% and 15.9%,respectively.Especially in high-speed conditions,the soil disturbance and the quality of work are significantly improved.