油菜高速直播机开畦沟装置刀组优化与试验

Optimization and experiments of the blade group of ditching devices in rapeseed direct seeder

针对长江中下游现有油菜机驱动型开畦沟装置高速(≥10 km/h)作业存在功耗较大、沟形不稳定的现实问题,该研究设计了一种刀体低阻触土面近似为螺旋桨叶面的类螺桨式开畦沟装置。基于运动学、动力学设计了由4组刀盘组成的类螺桨式刀组,确定了影响其作业功耗、作业质量的关键参数范围。基于EDEM软件开展了刀片刃型、螺距角及弯折角的单因素试验,结果表明:后磨刃耕阻最小,螺距角增大使刀片耕阻先减小后增大、抛土性能下降,弯折角增大使整体耕阻减小、抛土性能下降;1~4号刀盘的刃角结构为后磨刃,螺距角分别为7°、5°、4°、3°,折弯角分别为120°、120°、90°、90°时阻力较小,抛土性能较好。以螺距角、作业速度和刀盘转速为因子的Box-Behnken仿真试验,采用遗传算法对功耗和抛土性能进行多目标优化,结果表明:作业速度、刀盘转速、螺距角增大均使功耗上升,其中作业速度影响最大;作业速度降低、刀盘转速增高均使抛土效率提高;优化后1~4号刀盘对应的的螺距角分别为6.7°、4.7°、3.5°、2.5°;作业速度6、9、12 km/h时刀盘较优转速分别为540、620、810 r/min,优化刀组作业功耗低于对照组和国际ⅠS225刀组,总功耗较对照组分别降低5.51、11.78、28.99 kW,且12 km/h时减阻率最高,约为41%。田间试验表明:作业速度6~12 km/h时优化后开畦沟装置的总功耗为15.1~41.8 kW,与仿真结果相对误差小于10%,沟宽、沟深稳定系数均达90%以上。研究结果可为长江中下游稻油轮作区油菜高速开畦沟装置的优化改进提供参考。

A ditching device has been widely used for rapeseed direct-seeding in the rice-oil rotation areas of the mid-lower reaches of the Yangtze River.However,the high-power consumption and unstable furrow shape cannot fully meet the large-scale production in recent years,when operating at the high speed(≥10 km/h).In this study,a quasi-propeller ditching device was developed with a blade-soil contact surface similar to that of a propeller suitable for high-speed no-tillage rapeseed direct seeder.The ditching blade group was also optimized.A quasi-propeller cutter group consisted of four sets of cutters.The blade layout structure was then determined using kinematics and dynamics.An optimal model of power consumption and soil throwing efficiency was established for the operation of the blade group using dynamic analysis.The key structural parameters and working factors were determined to improve the power saving and soil throwing efficiency in the ranges of parameters.Single-factor tests were conducted on the blade edge type,pitch angle,and bending angle using EDEM software.The results show that the smallest resistance was achieved in the back blade edge type;The blade resistance first decreased and then increased,as the pitch angle increased,whereas,the soil throwing performance decreased significantly;There was a decrease in the overall resistance of the blade group and the soil throwing performance,as the bending angle increased.Once the blade edge structure of the cutter-1,cutter-2,cutter-3,and cutter-4 was the back edge(BE)type,the pitch angles were 7°,5°,4°,and 3°,respectively,and the bending angles were 120°,120°,90°,and 90°,indicating the relatively small resistance of the cutter group and the better performance of soil throwing.A Box-Behnken simulation test was conducted on the pitch angle,working velocity,and cutter rotary speed,according to a single factor test.A genetic algorithm(GA)was also used for the multi-objective optimization in the power consumption and soil throwing performance.Box-Behnken results showed that the pitch angle,cutter rotary speed,and working velocity greatly contributed to the power consumption.The most significant impact was found on the working velocity,indicating the lower working velocity and the higher cutter rotary speed,while the higher efficiency of soil throwing.After optimization,the optimal pitch angles of cutter-1,cutter-2,cutter-3,and cutter-4 were 6.7°,4.7°,3.5°,and 2.5°,respectively;The optimal rotary speeds of the cutter were 540,620,and 810 r/min,respectively,at the working velocity of 6,9,and 12 km/h;The power consumption of the optimized blade group was lower than that of the control group and the international IS225 blade group;The total power consumption of the optimized cutter group was reduced by 5.51-28.99 kW,compared with the control group.The higher the working velocity was,the higher the resistance reduction rate was;The reduction rate of resistance was the highest at 12 km/h,about 41%.Field experiments showed that the total power consumption of the optimized ditching device was 15.1-41.8 kW when operating at a speed of 6-12 km/h,with a relative error of less than 10%,compared with the simulation.The width range of the furrow was 421.3-452.7 mm,the depth range was 163.7-178.7 mm,the stability coefficient range of the furrow width was 95.2%-98.6%,and the stability coefficient range of the furrow depth was 93.8%-97.5%.The working velocity also caused the furrow pattern to change from a circular arc to a V-shape.This research can provide a strong reference to improve the high-speed ditching device for the rapeseed direct-seeding in the rice-oil rotation cropping area of the mid-lower reaches of the Yangtze River.