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ID:36923624
大小:3.72 MB
页数:58页
时间:2019-05-11
《圆柱齿轮公差与检测》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、第7章圆柱齿轮公差与配合应用Chapter7Cylindricalgear'stoleranceandfitapplication基本要求Basicrequirements目的:了解圆柱齿轮的公差标准Aim:TounderstandtolerancestandardsofCylindricalgear初步掌握:Grasppreliminarily:1.应用要求、加工误差Applicationrequirementsandmanufacturingerror2.评定指标Evaluationindex3.图样
2、标注Labelsofpattern4.齿轮精度设计Designofgearaccuracy操作技能:评定指标的检验Manipulativeskill:Thetestofevaluationindex.特点Traits1结构紧凑Compactstructure2恒定的传动比Constanttransmissionratio3传动效率高Hightransmissionefficiency4可实现平行轴、相交轴和交错轴之间的传动Itcouldrealizethetransmissionbetweenparallel
3、axles,intersectantaxlesandinterlacedaxles5使用寿命长Longworkinglife6维护保养简单Sampletomaintain作用:传递空间任意两轴(平行、相交、交错)的旋转运动,或将转动转换为移动。Founction:Totransmittherevolvingmovementsofanytwoaxles(parallel,intersectantandinterlaced)inspace.Andtoconvertturntoshift.缺点:要求较高的制造和安装
4、精度,加工成本高、不适宜远距离传动。Disadvantages:Itneedshigheraccuraciesofmanufactureandinstallment.Conversioncostishighanditisnotsuitableforlongdistancetransmission.齿轮传动的类型Typesofgeardrive传动齿轮:转速较高,功率较大(汽车飞机等变速装置)Drivegear:Higherrotationrateandpower(Speedvariatorsinautomob
5、ilesandairplanes)动力齿轮:转速不高,传递扭矩(矿山机械起重机械)Powergear:Thespeedofrevolutionisnothighandittransmitstorque(miningmachineandhoistingmachinery)分度齿轮:精确回转(精密机床仪表中的分度装置)Dividinggear:Preciserotation(precisionmachinetoolanddividingdeviceininstrumentation)齿轮传动机构组成Theform
6、ofgeartransimissionmechanism齿轮副、轴、轴承、箱体…pairofgears,axles,bearingsandboxes…失效形式failuremode轮齿折断toothbreakage1.由于多次重复的弯曲应力和应力集中造成的疲劳折断;Thefatiguefracturewhichiscausedbyoft-repeatedbendingstressesandstressconcentration.2.由于突然严重过载或冲击载荷作用引起的过载折断。Theoverloadbreak
7、whichiscausedbysuddensevereoverloadorimpactload.直齿轮:齿宽较小的往往发生全齿折断,齿宽较大的直齿轮或斜齿轮则容易发生局部折断。Straightgear:Thegearswithsmallerbreadthoftoothoftenemergewholetoothfracturewhilethestraightgearsorhelicalgearswithbiggerbreadthoftoothareeasytoemergelocalbreak.一、轮齿的失效形式
8、失效形式齿面点蚀Toothsurfacepitting原因:由于在齿面啮合处脉动循环变接触应力长期作用下,当应力峰值超过材料的接触疲劳极限,经过一定应力循环次数后,先在节线附近的齿廓表面产生细微的疲劳裂纹。随着裂纹的扩展,将导致小块金属剥落,产生齿面点蚀。Reason:Becauseofthelongtermeffectofpulsatingcyclicvariablecontactstresson
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