林地开沟机刀具优化设计与试验

Optimum design and test of cutting tools for forest ditcher

针对林地开沟条件恶劣、开沟困难的情形,设计一种开沟刀,对设计的开沟刀进行切削土壤研究与参数优化。利用LS-DYNA建立开沟刀—土壤切削有限元模型,得到开沟刀土壤切削过程等效应力、切削阻力以及切削能耗的变化规律。以平均切削阻力为指标,建立正交仿真试验,探究刀片厚度、刃倾角和刀片切削速度对平均切削阻力的影响。正交仿真试验结果表明:平均切削阻力最小时的最优参数组合为刀片厚度6 mm,刃倾角45°,刀片切削速度2 m/s;各因素影响平均切削阻力的顺序为刀片切削速度>刀片厚度>刃倾角。对优化后的开沟刀进行静力学分析,刀具的强度与刚度满足要求。林地试验开沟刀切削阻力平均值为232.6 N,试验值与仿真值误差为7.1%,表明开沟刀—土壤切削模型可用于开沟刀参数优化。

In view of the poor ditching conditions and difficult ditching of forest land,a ditching knife was designed,and the cutting soil and parameter optimization of the designed ditching knife were carried out.The finite element model of trench cutter-soil cutting was established by LS-DYNA,and the variation laws of equivalent stress,cutting resistance and cutting energy consumption in the soil cutting process of trench cutter were obtained.Taking the average cutting resistance as the index,the orthogonal simulation experiment was established to explore the influence of blade thickness,blade angle and blade cutting speed on the average cutting resistance.The orthogonal simulation results showed that the optimal parameter combination with the minimum average cutting resistance was blade thickness of 6 mm,blade inclination angle of 45°,and blade cutting speed of 2 m/s.The order of factors affecting the average cutting resistance was blade cutting speed>blade thickness>blade inclination.The static analysis of the optimized trench cutter showed that the strength and stiffness of the cutter met the requirements.The average cutting resistance of the ditching cutter in the forest land test is 232.6 N,and the error between the test value and the simulation value is 7.1%,indicating that the ditching cutter-soil cutting model can be used to optimize the ditching cutter parameters.