自激振动旋耕刀设计与减扭降耗性能分析

为实现旋耕作业减扭降耗，在国标IT245旋耕刀基础上设计了一种自激振动旋耕刀装置，对其工作原理进行了阐述。通过运动受力分析，完成了其大弹簧参数选型与弹簧心轴腰型孔设计。基于DEM-MBD技术，建立土壤-旋耕刀相互作用仿真模型，分析5种刀轴转速下国标旋耕刀与自激振动旋耕刀所受三向阻力与扭矩变化规律。仿真试验中，刀轴转速为150、200r/min时，减阻降扭效果不明显；转速为250、300r/min时，自激振动旋耕刀相比国标旋耕刀的减阻降扭效果较好，垂向阻力分别降低6.96%、10.41%，且平均扭矩降低率较大，分别为9.80%和19.63%，而转速达到350r/min时，减阻降扭效果下降。通过对2种旋耕刀仿真与土槽试验的平均扭矩进行分析，得出了国标旋耕刀与自激振动旋耕刀平均扭矩变化曲线的相关系数，分别为0.997与0.998，基本验证了DEM-MBD耦合仿真模型的准确性。对土槽试验中采集的Y向（耕作时刀刃振动主要发生方向）振动加速度数据进行频域分析表明，随着刀轴转速的增加，Y向功率谱密度幅值总体呈上升趋势，转速达到300r/min时，激振频率达到装置Y向的固有频率附近，此时发生共振，Y向功率谱密度幅值达到最大值。即此时旋耕刀获得最大能量，扭矩降低幅度最大，减扭降耗的效果最佳。

Design of Self-excited Vibrating Rotary Tiller and Analysis of Its Performance in Reducing Torsion and Consumption

In order to reduce torsion and consumption in rotary tillage operation, a self-excited vibration rotary blade device was designed based on the national standard IT245 rotary blade, and its working principle was described. Through the analysis of motion force, the selection of large spring parameters and the design of waist hole of spring spindle were completed. Based on DEM-MBD technology, the simulation model of soil rotary tiller interaction was established, and the variation law of three-dimensional resistance and torque of national standard and self-excited vibration rotary tiller under five knife shaft speeds was analyzed. In the simulation test, the effect of drag reduction and torque reduction was not obvious at the low speed when the cutter shaft speed was 150r/min and 200r/min. When the rotating speed was 250r/min and 300r/min, the self-excited vibration rotary blade had better drag and torque reduction effect than the national standard rotary blade. The vertical resistance was reduced by 6.96% and 10.41%, respectively, and the average torque reduction rate was larger, which were 9.80% and 19.63%, respectively. When it reached 350r/min, the drag and torque reduction effect was reduced. By analyzing the average torque of two kinds of rotary tiller simulation and soil tank test, the correlation coefficients of the national standard and the average torque curve of self-excited vibration rotary tiller were obtained, which were 0.997 and 0.998, respectively, which basically verified the accuracy of DEM-MBD coupling simulation model. The frequency domain analysis of the vibration acceleration data in the Y-direction collected in the soil trough test showed that with the increase of the rotating speed of the cutter shaft, the amplitude of the Y-direction power spectral density generally showed an upward trend. When the rotating speed reached 300r/min, the excitation frequency reached near the natural frequency of the installation in the Y-direction. At this time, resonance occurred, and the amplitude of the Y-direction power spectral density reached the maximum value. At this time, the rotary tiller obtained the maximum energy. The torque reduction was the largest, and the effect of reducing torque and consumption was the best.