14 届毕业设计玉米脱粒机设计学生姓名 学 号 所属学院 机械电气化工程学院 专 业 班 级 指导老师 日 期 机械电气化工程学院制前 言我国是农业大国，农业是国民经济基础。党和政府对农村、农业和农民问题十分重视。中共十六大提出，统筹城乡经济社会发展，建设现代农业，发展农村经济，增加农民收入，是全面建设小康社会的重大任务。建设现代农业，推进农业产业化与现代化，提高农产品竞争力，努力增加农民收入，需要加快农业机械化发展。这既是解决农业劳动生产效率低、经济效益不高的重要措施，也是缩小城乡差别，提高农业和农村整体水平的重要条件。玉米是我国三大粮食作物之一，同时也是重要的饲料和工业原料。我国年种植面积3.67亿亩,目前我国已形成三大玉米生产区。一是北方玉米区，包括吉林、黑龙江、辽宁、河北等省市，播种面积占全国40；二是黄淮平原春夏玉米区，包括山东、河南、江苏等省市，播种面积占25；三是西南丘陵玉米区，包括云贵等省，约占播种面积15。三大玉米产区种植面积占全国80以上。大力发展粮食生产机械化，提高劳动生产率和粮食单产，改善粮食品质，节约生产成本，是增加粮食主产区农民收入的一条重要途径。研究玉米脱粒机的设计，发展玉米生产机械化，对于稳定和提高我国粮食生产能力，减轻农民负担，提高农业的生产率，提高农业收入，具有重要意义。第一、解决粮食供给问题的需要。我国有13亿人口，每年还纯增人口1000多万，耕地逐年减少，粮食供给形式十分严峻。国外曾有人预言，21世纪中国的粮食难以自给，甚至提出“谁来养活中国”的论调，进而得出了中国威胁论。为了使这些预言破产，同时也真正解决我国庞大人口的实际粮食需求，解决我国粮食安全问题，我国采取可扩大玉米种植面积和提高玉米单产等多项措施。其中，提高单产靠选用高产优良品种、紧凑型玉米种植模式、覆盖、移栽、机械收获等措施。我国粮食问题从长远来看，不单是口粮问题，还有饲料问题，其中主要是玉米问题。因为随着人民生活水平提高，饮食文化的提高，人均口粮下降，需要更多的饲料，而饲料首选作物是玉米。玉米面积的不断扩大，单产不断提高，对玉米生产机械化发展提出了客观需求。第二、对提高玉米产量的需求。我国玉米总产量居世界第二，但单产却比美国低56%，位居世界第28位，增产潜力极大。粮食的增产，带来农民收入的提高，必将推动玉米生产机械化的发展。玉米收获作为玉米生产的主要环节，也是玉米生产实现机械化不可逾越的关隘。第三、发展玉米生产机械化是农业生产的必然，也是农业机械化发展的客观要求。解决玉米生产的机械化间题是广大农民群众的迫切要求，是农业生产的急需，玉米生产机械化水平低，尤其是收获机械化水平极低，已经成为制约农业机械化发展的瓶颈。目前，收获机械化程度很低，收获基本靠人工完成，劳动强度大，效率低，“三秋”时间拖得很长，有些地区(一年两熟地区)影响适时种麦。因此，提高玉米收获机械化水平已成为当务之急。关键词： 农业，玉米，脱粒机，粮食，发展AbstractChina is a large agricultural country,agriculture is the foundation of the nationaleconomy.The party and governmentattach great importance to theproblem of countryside,agriculture and farmers.Sixteen National Congress of the CPCput forward,urban and rural economic and social development,build modern agriculture,develop the rural economy,increasing the income of farmers,is themajor task of building a well-off society.The construction of modern agriculture,promote agricultural industrializationand modernization,improving the competitiveness of agricultural products,increase the income of farmers,tospeed up the development of agricultural mechanization.This isan important measure to solve theagricultural work efficiencyis low,the economic benefit is not high,but alsoreduce the differences between town and country,the important condition to improvethe overall level ofagriculture and rural areas.Corn is one of the threemajor graincrops in China,but also an importantfeedand industrial raw materials.Our annualplanting area of 367000000mu,at present our countryhas formedthree majormaizeproduction area.One is theNorth maize region,including Jilin,Heilongjiang,Liaoning,Hebei and other provinces and cities,the sown areaaccounted for 40%;two isthe Huang Huai plain springcornregion,including Shandong,Henan,Jiangsu and other provinces and cities,the planting area of25%;three is thecornregion in SouthwestHilly,includingthe Yunnan GuizhouProvince,accounting for about15% ofthe sown area.The three majorcorn producing areasof plantingarea accounts formore than 80%.We will vigorously develop grainproduction mechanization,improve labor productivityandimprove thegrain yield,grain quality,saving the cost of production,isan important way toincreasethe income of farmersin major grain producing areas.Design and researchof corn thresher,the development of the corn productionmechanization,to stabilizeand improve grainproduction capacity in China,reduce farmer burden,improve agriculturalproductivity,improve the agricultural income,has the vital significance.First,to solve the problem of foodsupply.China has a population of 1300000000,annualnet increase ofabout 10000000 population,cultivated landis decreasing year by year,the food supplysituation is very austere.Foreign hadpredicted,twenty-first CenturyChinesefoodtoself-sufficiency,and even the who will feedChinese argument,then that theChinathreat.In order to make thesepredictions of bankruptcy,but alsosolvethe actual fooddemand of Chinashuge population,solvingthe problem of food security in China,our country adoptedcanexpand the planting areaof maize andmaizeyielda number of measures such as.Among them,increasing the yield per unit areaon theselection ofhigh-yield varieties,compact type maizecropping pattern,coverage,transplanting,harvesting machineryand other measures.The food problem in Chinain the long run,is not only theissue of rations,andfeed problem,which is the mainproblem ofmaize.With theimprovement of peoples living standard,food cultureimprove,per capitafooddown,need morefeed,andfeedcorncropispreferred.The maize areacontinues to expand,improve yields,the objectivedemandofthe development of corn productionmechanization.Second,toincrease the yield of maizedemand.Chinastotal cornproduction ranks second in the world,but the yieldislower than 56%America,ranking twenty-e