| Our country has abundant cultivated land resources,but average per capita cultivated land is less,belongs to the country that average per capita cultivated land area is relatively scarce.However,the quality of cultivated land resources has been seriously threatened due to the decrease of soil fertility and fertility of cultivated land and the shallower soil and the upward shift of plough base caused by continuous ploughing and shallow rotation.Based on the above analysis,in order to change the status quo of cultivated land quality,in addition to implementing the mode of rotation and fallowing,we should also increase the depth of tilling layer and break the tilling layer to improve the tilling environment.Vertical rotary tillage is a deep farming technology that can not only break the plow bottom to increase depth of cultivation,but also has characteristics such as good soil breaking effect and no soil loss in tillage.While it does not disrupt the spatial structure of the soil layer,it can also adapt to high-speed operations and has good application prospects under the background of promoting large-scale planting and soil quality improvement in our country.However,there are some outstanding problems in the application process of vertical rotary farming technology in the market,such as in the blade design link,the production of vertical rotary farming blade manufacturers are many,but the manufacturers do not have a unified standard in the design of the blade,some businessmen design the blade structure is not reasonable,leading to the rotary farming blade operation effect is poor,short life.In addition,in the application,due to the improper selection of operation parameters,resulting in the vertical rotary tillage operation effect quality is not up to standard,the resistance and resistance moment of the machine is also very large,can not meet the requirements of the operation.Therefore,it is of great significance for the promotion and application of vertical rotary tillage technology to clarify the interaction mechanism between rotary tillage cutter and soil in the process of vertical rotary tillage operation,analyze the influence of the structural design parameters of vertical rotary tillage cutter on the operation effect,analyze and optimize the optimal operating parameters of vertical rotary tillage to guide practical production.This paper intends to analyze the operation process of vertical rotary tillage through discrete element simulation and field comparison experiment,and analyze and optimize the structural parameters and operation parameters of the key component of vertical rotary tillage.The specific research contents are as follows:(1)Determine soil parameters and establish discrete element simulation model.By testing the soil parameters used in the experiment and combining with the research basis of some scholars,the parameters of the topsoil and the subsoil of the plough required by the simulation test were obtained,and the soil particle model and the contact model between materials were determined.The three-dimensional boundary model of the vertical rotary tillage knife was established by Solid Works to complete the preliminary work of the simulation.(2)Discrete element simulation and theoretical analysis of vertical rotary farming operation.The preliminary simulation of vertical rotary tillage was completed.The motion of vertical rotary tillage knife and the force of soil particles were analyzed theoretically.The spatial triaxial resistance and torque of vertical rotary tillage blade and the macro disturbance and displacement of the vertical rotary tillage blade on soil were analyzed by simulation.(3)Optimize the geometric structure of vertical rotary tillage blade,and conduct mechanical analysis on the optimized rotary tillage blade to verify whether the strength and stiffness of the blade meet the actual operation requirements.Single factor experiment was designed to analyze the influence of the blade camber Angle,camber Angle,blade Angle,γ Angle and blade tip fillet radius on vertical rotary farming.Combined with the results of single factor experiment,the three parameters of blade camber Angle,enfolding Angle and blade Angle were further selected as the factors of orthogonal experiment.The significance of each factor to different indexes was analyzed by taking the resistance,torque and soil crushing effect of rotary tillage blade as indicators.By means of regression fitting and response surface analysis,the above three parameters were further analyzed and optimized,and better structural parameters of vertical rotary tillage cutter were obtained.A vertical rotary tillage blade model with optimized structure was established,and statics,dynamics analysis and modal analysis under prestress were carried out to verify that the strength and stiffness of the blade could meet the operation requirements.(4)Using the same method as vertical rotary tillage blade structure optimization,the main operating parameters of vertical rotary tillage,such as forward speed,blade rotation speed and tillage depth,were analyzed and optimized to obtain the influence of each parameter on the indicators of rotary tillage operation,such as force,torque,power and soil crushing rate,and optimize the optimal combination of operating parameters.(5)Based on the above research results,a vertical rotary tiller with optimized structure was trial-produced and assembled on a vertical rotary tiller.Field experiments were carried out with the assistance of Xizhai Agricultural Machinery Cooperative of Pingdu City,Qingdao.The operating indexes of the vertical rotary tillage blade with optimized structure were determined: the variation coefficient of tillage depth stability was 0.32%,the soil crushing rate was 96.10%,and the surface flatness after tillage was0.79 cm,which not only met the national standard,but also better than the common cutting blades in the market at present. |
