【作者】 贺俊林；

【导师】 佟金； 陈志；

【作者基本信息】 吉林大学 ， 农业机械化工程， 2007， 博士

【摘要】 不分行技术和低损伤摘穗技术是玉米收获机械化的关键技术。长期以来,不分行收获问题一直被视为玉米收获机发展的瓶颈,相当一部分人员呼吁统一玉米种植行距,要求种植农艺适应收获工艺。由于各地种植模式差异较大,而且玉米收获的时间性不像小麦那么紧迫,所以这一要求一直未能被接受,我国玉米收获机械化水平在2002年仅为1.73%,到2005年也只有3.12%。同时,玉米机械化收获中的基础理论工作也没有得到足够的重视。本研究工作在国家杰出青年科学基金项目“土壤机具系统摩擦学表面仿生研究”(50025516)、国家高技术研究发展计划(863计划)“不分行玉米收获机技术与装备”(2005AA420250)及其子课题“玉米联合收获机低损伤摘穗机构仿生表面技术”资助下,基于工程仿生基本原理和机械系统仿真方法,对玉米机械化收获中诸如不分行(不对行)收获技术和减轻机收损伤等关键性难点技术进行了系统的研究。分析了玉米收获机摘穗辊辊型、作业速度、摘穗辊转速和割台水平倾角四种因素对卧辊式摘穗机构性能的影响。探索玉米茎秆进入摘穗机构的姿态对摘穗机构性能的影响,通过仿真模拟确定保持玉米茎秆直立姿态的工作参数组合。应用机械系统动力学仿真软件MSC.ADAMS对玉米不分行(不对行)收获作业中分禾机理及其影响参数进行研究,以保持茎秆直立姿态为优化目标,分别探索了具有扶禾杆的链式分禾机构和具有指形拨禾轮的无链分禾机构之较优结构参数和工作参数。对适收期玉米植株的力学性能进行了研究,探讨了含水率和植株结穗高度对机械化收获的影响。依据工程仿生学原理,构思了旨在通过增大摘穗辊与玉米茎秆之间当量摩擦系数而增强攫取能力的具有表面凸起和凹坑的仿生几何结构表面的几种摘穗辊结构,并进行了田间考察试验。研制开发了卧辊式摘穗辊多因素试验台,并进行室内试验进一步考察玉米摘穗各因素对摘穗性能之影响,验证了新型具有仿生几何结构表面结构摘穗辊的实际效果。上述研究工作及其所取得的研究成果,对于玉米收获机械化技术基础性研究工作具有重要意义,对于仿生摩擦学研究是一项有意义的探索。更多还原

【Abstract】 Research & Development in corn (maize) no-row harvesting technology and its equipment is an urgent project at present in China. The FDP (Functional Digital Prototyping) is an advanced product development technology in 21st century. FDP is a quickly and effectively means for the mechanical products. But it isn’t reported that the FDP was used in R&D of the corn (maize) harvest machinery, at present, with the exclusion of the research works about this dissertation.This work was supported by National Science Fund for Distinguished Young Scholars of China, and Hi-tech Research and Development Program (863 Program) of China. The work puts forward to Research & Develop the no-row corn (maize) harvesting technology based on FDP, and centering on to analyze some key problems in corn (maize) harvesting technology, especially in the technology of lower damage with snapping rolls to pick down the corn (maize) ears based on bionical technology.Firstly, it was discussed that the key problems in corn (maize) harvesting, and the research thought and the technical route of the work was introduced. The design norm for snapping rolls design was bring forward after the detailed expounding on the working principle of pick off the ear from cornstalk. And some ignored questions in snapping corn cob was put forward. A series field tests for corn harvesting were done with the cooperative supports famed national corn harvester company. And series multi-factor tests were done in snapping rolls tester which was been trial-manufactured by this work. The degree of influencing factor on the performance of corn picking was demonstrated. The new type roll with bionic surface structures was been designed. By minishing the rolls diameter markedly based on the bionical engineering, the damage of snapping rolls was reduced evidently.Based on the CAD/CAE technology, the simulation model for the feed-in mechanism with guide rod of a national no-row corn harvester was set up. The kinematic simulation of holding and supporting the corn stalks was carried out for the diverse working parameters based on software MSC.ADAMS. The results demonstrated that the driving feed-in mechanism was able to avoid the forward collapse and the guide-rod played an important role of avoiding the lateral leaning in no-row corn harvesting. Some ameliorative suggestions were given for the designing of the feed-in mechanism.The feed-in mechanism model of a harvester with finger rotor has been researched based on CAD software. The mechanical dynamics software MSC.ADMAS was used to establish the 3-D kinematic simulation model of corn stalks feed-in mechanism for no-row corn harvesting. The process of making kinematics model and its simulating were been statement in detail. The simulation based on software MSC.ADAMS was successfully got along. The results demonstrated that the harvesting speed and the rotating speed of finger rotor were main influencing parameters on the performance of the feed-in mechanism. The shape of finger rotator, especially the shape of the fingers’ end, had a notable influence on the motion of corn stalks. Some ameliorative suggestions were provided to the corresponding physical mechanism.The no-row harvesting technology,the bottleneck in the development of maize (corn) harvest machinery, was lucubrated. The influencing principle of key components, the feed-in mechanical components with varying parameter, was been analyzed using the techniques of virtual simulation.The main contents and innovative works in the dissertation are as follows:a) The working principle of snapping corn ears was lucubrated on the base of present research in corn harvest machinery. The working process of snapping rolls with an obliquity was analyzed. It was put forward that the design norm for snapping rolls design aimed to lower damage of corn ears by rolls.b) The mechanics performance of cornstalk in harvesting period was been studied. Its influences of water content of cornstalks to corn harvesting mechanization were discussed. The results demonstrated that the water content is the main factor which influencing the harvesting performance and the height of corn ears isn’t observably related to the height of corn plant.c) A series field tests for corn harvesting were done with the main national corn harvester to discover the main factor which influencing the corn harvesting performance. The results were demonstrated that the rolls’ type play an important role in picking corn ears, and the working speed had an unobservable influence to picking corn ears but feed-in mechanism.d) A device for testing the performance of snapping rolls of corn harvester was researched and developed. The influencing factors on picking maize-cob were discussed. In the designing of the tester, the regulating and controlling factors influencing the roller-type picking mechanism were considered. The working factors can be adjusted and controlled in monofactorial tests & multifactorial tests. The snapping-rolls of main corn harvester made in China can be installed easily.e) According to the engineering bionics principle, several structures of snapping rolls with bionical geometry structures, protruding surface & concave hole on the roll’s surface, were been worked out to keep up the seizing ability by enlarging equivalent coefficient friction to between the cornstalk and the rolls which the diameter was observably minished. The field tests about it were conducted, and the results showed that the expectant purpose were come true. The sizes and mass was minished observably.f) The feed-in process of cornstalks was studied based on the theoretical, simulation analysis, and verifying testing. It is discovered which the basis to analyze the key mechanism for no-row corn harvesting. In the dissertation, the next research is suggested that the mechanics basis of corn plants and the innovation of corn-pick mechanism. The studies should go on in the cooperation with multi-system and multi-domain, and the R&D of corn (maize) harvesting technology should lucubrate between the whole work tache.更多还原