基于离散元法的冬小麦划锄断根追肥联合作业装置设计与试验

Design and Experiment of Combined Operation Device for Hoeing, Root Cutting and Topdressing of Winter Wheat Based on Discrete Element Method

摘要:

结合冬小麦返青期划锄断根与追肥深施作业农艺要求,针对行间断根和化肥深施联合作业需求,设计了一种划锄断根追肥联合作业装置,以降低作业阻力、提高断根率并保证施肥深度为目标,系统开展了结构设计与参数优化研究。首先,基于作业机理分析与力学建模,对开沟器、断根铲及施肥管等关键部件进行了结构设计,提出了开沟器前刃采用指数曲线、施肥管采用最速降线曲线的设计方案;其次,基于离散元法(DEM)构建了划锄断根追肥联 合作业装置-土壤-根系-肥料仿真模型。以断根率和作业阻力为评价指标,对断根铲刃线型、入土角和翼张角等关键参数进行了分析,并结合小麦农艺需求确定了合理参数范围;在此基础上,采用Box-Behnken 正交组合仿真试验进行参数优化,得到断根铲的最优结构组合为:铲刃为阿基米德螺旋线、入土角6.43°、翼张角54.99°;优化后的结构参数可提高断根率并降低作业阻力;最速降线施肥管仿真结果显示施肥深度合格率最高达到94.0% ,排肥过程稳定。田间对比试验表明,在作业速度4km/h条件下,划锄断根追肥联合作业装置作业效果良好,平均断根深度为117mm,断根率达82.9% ,施肥深度合格率为90.6%,所设计装置能实现划锄断根追肥深施作业功能。

Abstract:

Aiming to meet the agronomic requirements for hoeing, root-cutting, and deep fertilization during the winter wheat greening stage, and address the need for integrated inter-row root-cutting and fertilizer application, an integrated hoeing, root-cutting, and topdressing device was designed. With the objectives of reducing draft force, increasing the root-cutting rate, and ensuring fertilization depth, structural design and parameter optimization were systematically conducted. Firstly, based on operation mechanism analysis and mechanical modeling, key components, including the furrow opener, root-cutting shovel, and fertilizer tube were designed. A design scheme was proposed, featuring an exponential curve for the leading edge of the furrow opener and a brachistochrone curve for the fertilizer tube. Secondly, a discrete element method ( DEM) simulation model for the “ integrated device-soil-root-fertilizer” system was established. Using the root-cutting rate and draft force as evaluation indicators, key parameters such as the shovel blade profile, penetration angle, and wing angle were analyzed, and reasonable parameter ranges were determined based on wheat agronomic requirements. Subsequently, a Box Behnken design simulation experiment was employed for parameter optimization. The optimal structural combination for the root-cutting shovel was determined to be an Archimedes spiral blade profile, a penetration angle of 6.43°, and a wing angle of 54.99°. The optimized structural parameters effectively increased the root-cutting rate and reduced draft force. Simulation results for the brachistochrone fertilizer tube showed a maximum fertilization depth qualification rate of 94% with a stable discharging process. Field comparative experiments indicated that at an operating speed of 4km/h, the integrated device performed well, achieving an average root-cutting depth of 117 mm, a root-cutting rate of 82.9% , and a fertilization depth qualification rate of 90.6%. The results confirmed that the designed device successfully fulfilled the functions of hoeing, root-cutting, and deep fertilizer application.