【作者】 张卓；

【导师】 贾洪雷；

【作者基本信息】 吉林大学 ， 农业机械化工程， 2019， 博士

【摘要】 近年来,我国为了在有限的土地上平衡玉米和大豆的产量,逐步摸索出多种适合东北地区实际情况的轮作技术,其中玉米大豆轮作技术是逐渐兴起的一项轮作技术。玉米大豆轮作技术为前两年播种玉米,第三年播种大豆,依次循环往复,这种轮作技术具有蓄水保墒、降低风蚀水蚀、根茬降解腐烂程度高、增加土壤有机质含量等优势。由于采取玉米大豆轮作模式,因而在大豆播种作业时,地表上残留大量玉米秸秆和根茬,致使大豆播种作业时发生如下问题:秸秆、根茬易堵塞开沟装置,破茬作业需同时针对秸秆和根茬进行作业;在播种过程中解决大豆的精密排种问题;拖拉机行驶轮和机具在作业时均会接触到残留于地表的根茬,机具震动增加,排种器易发生掉种现象。上述问题使传统的大豆播种机很难适用于玉米大豆轮作种植模式,因而本文对玉米大豆轮作模式下的精密播种技术进行深入研究,并研制一种适用于玉米大豆轮作技术的大豆耕播机。本研究结合玉米大豆轮作技术特点和东北地区实际作业条件,通过理论分析、试验设计、数学建模、仿真分析等方法,研究关键部件的几何形态、结构参数、作业方式与作业效果之间的关系,并总结和量化其规律,从而设计出合理的排种、破茬、传动等关键部件,最终设计出与玉米大豆轮作技术相配套的大豆耕播机具。1、针对玉米秸秆覆盖模式下的破茬需要,本研究设计了一种适用于玉米大豆轮作种植模式的播种机防堵装置,其采用组合刀片式结构,具有作业功耗小、秸秆切断率高等优点。通过理论建模和动力学分析相结合的方法,对滑切刀片滑切秸秆的过程进行研究,得出滑切刀片侧切刃最优曲线应为一条等滑切角曲线。通过三因素三水平正交组合试验得出滑切刀片的最佳参数组合为:作业速度2 m/s、耕作深度35 mm、滑切刀片回转半径为185 mm,并进行验证试验得出秸秆切断率为91%,单把刀片功耗为8.2 W。2、设计了一种大豆气吸式双圆盘排种器。通过分析气吸式双圆盘排种器取种、排种作业原理,对其关键部件进行了设计、优化。以排种器播种吸盘转速、气流运动速度为试验因素,漏播率为试验指标分别进行单因素试验和二次通用旋转组合试验,运用Design-Expert软件得出回归曲面并建立数学模型,得出最佳因素组合为气流速度220 m/s、排种器播种吸盘转速100 r/min,此时漏播率为2.79%。3、本文设计的液控起降摩擦轮传动装置,通过理论分析和现有研究资料对比确定两个传动轮胎的径向尺寸,并合理选择传动轮胎。将整个传动机构建立三维模型,运用ADAMS仿真软件实现传动机构的运动学仿真分析,取得了东北地区坡度等级下的摩擦轮作业过程中的纵向偏差。经计算可知实现传动的最大摩擦轮胎压值为25.9psi。根据田间试验测试摩擦轮传动装置的传动效果,通过更改摩擦轮胎压值测量各轮胎转数和移动距离,并根据测得结果计算对比不同胎压摩擦轮的滑移率,做出摩擦轮的滑移率变化曲线,并求得摩擦轮传动效果最好的胎压最优值为24.345 psi。4、针对保护性耕作条件下与大豆耕播机配套的镇压辊压实土壤不均匀、相关耕播机具纵向尺寸过长的问题,设计了一种仿形弹性镇压辊,采用弹性辐条结构,通过理论分析确定了镇压辊的主要结构参数:直径D=450 mm,宽度B=210 mm,弹性辐条数量n=12。综合上述技术,本文研制了2BDG-6型大豆耕播机,经田间试验表明其在作业速度6 km/h的前提下,粒距合格指数86.8%,漏播指数5.2%,播种深度合格率93.75%,种子破损率仅为0.3%,机具的各项性能指标均超过国家相关标准规定的指标要求,可为玉米大豆轮作技术在东北地区的推广起到装备与技术支撑作用。更多还原

【Abstract】 Recently,in order to balance the production of corn and soybeans on limited land,China has gradually explored a series of rotation techniques that were suitable for Northeast China.Amongst these,corn-soybean rotation attracted much of the attention as a rising and promising rotation technique.In a typical cycle of the corn-soybean rotation,the corn was planted for the first two years with another one year planting of the soybean.The advantages of the corn-soybean rotation included the soil moisture retaining and conserving,the reduction of wind-water erosion,the high corrosion of the stubble degradation,the increase of the organic content in soil,et al.In the planting of the soybean,some problems arose from the residual of lodging maize straw and stubble on the earth surface.The maize straw and stubble would easily block ditching equipments,increasing the difficulty of stubble-breaking.The precision seed arrangement problem of soybean is to solve during sowing.The seed dropping would easily occur due to the shake of the seeding apparatus when the tractor wheels and machineries were exposed to the maize straw and stubble on the earth surface during the operation.Thereby,the conventional soybean planters seemed to be unsuitable for the corn-soybean rotation.It was significative to deeply study the precision planting technique for corn-soybean rotation.The development of an appropriate soybean planter for corn-soybean rotation.Focusing on the design of soybean planter for corn-soybean rotation,the present study detailedly investigated the geometric forms,structural parameters,the relationship between the operation mode and operation effect of the critical components of the machinery.The study was consisted of the theoretical analysis,the experimental design,the construction of mathematical models,and the simulation analysis,et al.The regular patterns had been summarized and quantified.The critical components of the seed discharging,stubble breaking,and earth repressing were legitimately designed.Firstly,we had designed an anti-blocking device for the soybean till-planter to appropriately work in the situation of the residual of lodging maize straw and stubble on the earth surface in the process of corn-soybean rotation.The designed device had a blade combined structure with the advantages of low power consumption and high straw cutting rate.The process of the straw cutting had been investigated via the methods of theoretical modeling and kinematics analysis.The optimal curve of the side cutting edge of straw cutting blade was established to be an equal slip angle curve.Through the orthogonal test of three factors and three levels,it was found that the optimal parameters of the straw sliding blade were 2.1 m/s for the operating speed,35 mm for the tillage depth,and 185 mm for the blade radius of gyration.The straw cutting rate and the power consumption of single blade had been established to be 90.9% and 8.15 W via the experimental results.Secondly,a biased double disc air suction metering device for the soybean till-planter had been designed.The principles of the seed extraction and the seed discharging were analyzed,and the critical components of the device were optimized.The single factor test and the general quadric rotation test had been carried out by using the rotating speed of the seeding sucker and the velocity of the airflow as test factors,and the rate of seed missing as test index.The optimal factors were established to be 220 m/s of the airflow velocity,100 r/min of the rotating speed of seeding sucker on the basis of the simulating model of the Design-Expert software.The rate of seed missing was calculated to be 2.72%.Thirdly,a hydraulic control friction wheel transmission device had been designed.The radial dimensions and the reasonable choice of the transmission tyres were established by the theoretical analysis.The relationship between the tire pressure,the deformation and the loading could be obtained on the basis of the analysis of the friction wheel transmission device.The three-dimensional model of the whole component was formed on the basis of the kinematics simulation analysis of Adams simulation software.The maximal friction tire pressure value for the transmission was calculated to be 25.9 psi.Based on the field trial results of the transmission effect of the friction wheel transmission device,the slip rate curve of the friction wheel was formed by changing the measured tire revolutions and moving distances of the friction tires and the comparison of the slip rate of friction wheel under different tire pressures.The optimal value of the tire pressure for best transmission effect of the friction wheel was calculated to be 24.345 psi.Fourthly,in order to resolve the problems of the uneven soil compaction and the long longitudinal dimension of the till-planter,we designed a copying elastic press roller with the elastic spoke structure.Based on the results of the theoretical analysis,the major structural parameters such as 450 mm of the diameter,210 mm of the width,and 12 of the elastic spoke value for the repression roll had been established.In summary,we had successfully designed the 2BDG-6 soybean till-planter.The results of the field trial revealed 86.8% of the grain spacing conformity index,5.2% of the leakage index,93.75% of the qualification rate of seeding depth,and only 0.3% of the seed crushing rate under 6 km/h of the working speed.All the performance indexes of the machines exceeded the requirements of the relevant national standards.The designed planter could play an important role in the promotion of corn-soybean rotation in Northeast China更多还原