【作者】 张志强；

【导师】 张军昌；

【作者基本信息】 西北农林科技大学 ， 机械， 2025， 硕士

【摘要】 西北旱区玉-麦轮作区在免少耕条件下多采用全量粉碎还田,小麦播种时种床上存在大量玉米秸秆,导致秸秆与土壤混杂,小麦出苗率下降,同时也造成作业时机具的堵塞。现有主动防堵刀具的研究多以减少阻力、降低功耗为主要目标,对玉米秸秆的切割和抛撒机理研究较少,本文采用切抛刀与旋耕刀组合的防堵装置,运用运动学分析、力学模拟试验、离散元仿真分析、田间试验等方法,探究了切抛刀对秸秆切割和抛撒机理的影响,并对其结构参数和工作参数进行了设计和研究,主要研究内容和结论如下:（1）玉米秸秆切割机理研究与切抛刀刃口曲线设计。本研究基于滑切机理优化玉米秸秆切割性能,通过文献分析确定滑切角为关键参数,结合田间复杂情况选取滑切角与斜切角作为变量。本试验通过自主设计的秸秆夹具与刀具,依托万能材料试验机进行秸秆切割试验。通过力学分析表明,秸秆切割过程呈现三阶段特征,其中以切割阶段（临界应力破碎）应力最大值作为参考,通过计算确定每组试验的秸秆剪切强度与单位切断功耗,基于二次回归正交设计建立数学模型,经方差分析（P<0.01）验证,确定最优滑切角为46°。分析不同曲线,确定等角螺线刃口的刀具对秸秆切割保持一定的滑切角,最终刃口曲线方程式为:ρ=е^0.9657θ。（2）玉米秸秆抛撒机理研究及切抛刀结构参数优化。本研究通过构建秸秆抛撒动力学模型,揭示切抛刀结构参数与作业参数的耦合机制。基于接触力学分析建立抛撒距离与折弯角γ、偏移角δ及转速ω的函数关系,采用正交试验设计在350 mm行距条件下构建三组防堵装置原型。根据小麦免少耕播种农艺要求,运用EDEM离散元平台建立土槽-秸秆复合模型,以种床清秸率为评价指标,通过Box-Behnken响应面法优化得出最佳参数组合:当γ=17°、δ=8°、ω=270 r/min时,中间种床清秸率达94.93%。（3）小麦免少耕播种机防堵装置设计与试验。本研究设计了以切抛刀与旋耕刀组合的防堵装置,实现秸秆切割抛撒（切抛刀）与种床土壤疏松（旋耕刀）的时序协同作业。基于2BMF-14型播种机构建原型机,重点优化施肥开沟器、播种管等关键部件结构参数与装配参数。田间试验数据显示:三次60 m作业中无堵塞,通过性能良好,种床清秸率达91.0%,平均土壤扰动宽度为132 mm,平均播深48.6 mm,平均施肥深度114.6 mm,各项指标变异系数均小于15%,且均符合小麦免少耕播种农艺规范。更多还原

【Abstract】 In the corn-wheat rotation areas of the arid northwest China,full straw incorporation under no/minimum tillage practices leads to significant mixing of corn stalks with soil during wheat sowing,resulting in reduced seedling emergence and frequent implement clogging.Existing active anti-blocking tools primarily focus on reducing resistance and power consumption,with limited research on the cutting and throwing mechanisms of corn stalks.This study proposes a combined anti-blocking device integrating cutting-throwing blades and rotary tillage blades.Through kinematic analysis,mechanical simulation,discrete element modeling（DEM）,and field experiments,the mechanisms of stalk cutting and throwing were investigated,with structural and operational parameters optimized.Key findings include:（1）Corn stalk cutting mechanism and blade edge curve design.Based on slip-cutting theory,the slip-cutting angle was identified as a critical parameter.Cutting experiments using a custom-designed stalk clamp and universal testing machine revealed a three-phase cutting process.Maximum stress during the critical fracture phase was used to calculate shear strength and specific cutting energy.A quadratic regression orthogonal model（validated by ANOVA,P<0.01）determined the optimal slip-cutting angle as 46°.The blade edge curve,following an equiangular spiral(equation:ρ=е^0.9657θ),maintained consistent slip-cutting performance.（2）Stalk throwing mechanism and structural parameter optimization.A dynamic throwing model was established to analyze the coupling effects of structural and operational parameters.Using DEM-based soil-straw composite models and orthogonal testing,the optimal parameters（γ=17°,δ=8°,ω=270 rpm）achieved 94.93%seedbed clearance under350 mm row spacing,meeting no-till sowing requirements.（3）Anti-blocking device design and field testing.A no-till wheat seeder integrating cutting-throwing blades（for straw processing）and rotary blades（for soil loosening）was designed.Based on the 2BMF-14 seeder,key components like fertilizer openers and seed tubes were structurally optimized.Field tests demonstrated zero blockages over three 60-m passes,with a 91.0%seedbed straw clearance rate.Average soil disturbance width was 132 mm,sowing depth 48.6 mm,and fertilizer depth 114.6 mm,all with coefficient of variation less than 15%,meeting no-till wheat agronomic standards.更多还原