谐波齿轮减速器设计及性能仿真【说明书+CAD+SOLIDWORKS】
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毕业设计(论文) 开题报告毕业设计(论文)题目:谐波齿轮减速器设计及性能仿真 专 业: 指导教师: 学生姓名: 学 号: 毕业时间: (一)选题的背景及意义背景:谐波传动是 20 世纪 50 年代中期随着空间科学技术的发展,在薄壳弹性变形的理论基础上发展起来的一种新型传动技术。由于谐波减速器具有回差小、单级减速比范围大、运动平稳、低噪声、传动效率高、承载力大、体积小、质量轻等多种其他减速器不具备的优点,因此一经问世就立刻引起了各国的普遍重视。美国、前苏联、日本、德国、英国等国家以及我国都开展了谐波减速器的理论、制造、加工、润滑等技术研究,美国等先进国家已将该项技术大量应用于空间飞行器的各种实施展开、驱动、精密指向、扫描、空间机器人活动关节等运动机构上,并已推广应用到地面雷达天线、通讯、电子、医疗器械、工业机器人、仪器仪表等多种行业中,获得了巨大的军事收益和社会效益。意义:虽然国内外学者几乎对该领域所有问题都进行过不同程度的研究,但仍有大量的基础性工作有待开展。作为决定传动寿命的柔轮疲劳强度的研究问题一直是研究谐波齿轮传动的重心。针对柔轮轴向尺寸大的问题,国外谐波齿轮传动多采用短杯柔轮,其体积小,重量轻、承载能力高;而国内的短杯谐波齿轮存在着轴向尺寸大,承载能力不高的缺点。国内的短杯谐波技术还处于研发阶段,没有成熟的产品。国外虽然有短杯柔轮,但是由于各国所采用的标准不一致和技术上的封锁,并考虑到进口产品价格昂贵等因素,所以研究开发出可以满足我国在紧凑空间环境中尺寸小,承载能力相对较大的特殊形状的谐波减速器对推动我国谐波减速器在宇航空间中的应用具有重要的意义。(二)研究内容拟解决的问题本课题在对谐波传动及齿轮传动相关知识熟练掌握的基础上,主要完成以下几个内容:确定杯形柔轮的结构、对柔轮的结构参数进行影响分析、谐波减速器的结构设计、谐波减速器的传动比、承载能力、传动效率的性能分析、对谐波减速器的传动效率、启动力矩、跑合温升进行研究。其结构形式决定着谐波传动的承载能力、传动性能、结构尺寸、使用寿命和加工工艺性等等。根据使用实践和试验研究,谐波齿轮传动最主要的失效形式是柔轮的疲劳断裂,因此,对于谐波齿轮中柔轮的进一步研究已经非常必要。由于谐波减速器有众多的优越性,因此谐波传动得到了广泛的应用。谐波传动有三个基本运动构件刚轮、柔轮和波发生器,如图 1-1 所示,图1-1 三大件结构示意例如:谐波传动不适用于小速比的传动,由于速比过小,柔轮的径向变形量增大,容易疲劳破坏;柔轮和波发生器的加工困难;对柔性轴承的材料及制造精度要求较高;杯形柔轮虽然应用广泛但是轴向尺寸大;柔轮在苛刻条件下(如高低温环境)容易失效。对于谐波齿轮传动在空间环境中的应用来说,柔轮的轴向尺寸大和柔轮在高低温环境下容易发生强度破坏是两个比较明显的问题。针对所设计的谐波减速器的具体结构参数,对传动比、承载能力、传动效率等参数做性能分析。分别分析两大核心部分各自的性能参数的影响,并给出谐波减速器的性能分析表。(三)研究方法技术路线:研究内容:传统的杯形结构的柔轮在当前的谐波减速器中应用极其广泛,具有结构简单、联接方便、制造容易、刚性较大的特点,具体的结构示意图如图 2-1 所示。但是就目前的产品来说,传统杯形的柔轮结构的轴向尺寸大的问题没有得到很好的解决,相比于国外相同机型的产品,还是存在较突出的体积大的缺点。这也大大的限制了谐波减速器在小空间中的应用。图 2-1 杯形柔轮结构图针对传统杯形柔轮的轴向尺寸较大的问题,本课题设计了三种不同于传统杯形结构的柔轮:直角圆弧回形结构的柔轮结构示意图如图 2-2 a)所示;“之”字结构的柔轮结构示意图如图 2-3 a)所示;直角直线回形结构的柔轮结构示意图如图 2-4 a)所示。这三种结构的特殊点在于改变了传统柔轮的杯筒和杯底结构,呈现回折的趋势。因此,这种提高了谐波减速器可用于结构紧凑的机构。 图 2-2 直角圆弧回形柔轮 图 2-3 “之”字结构柔轮图 2-4 直角直线回形柔轮研究方法: 通过改进设计,根据柔轮在不同工作条件下进行力学分析,进行三维造型。通过对不同机型柔轮的有限元分析比较,可以看出,相同机型、相同轴向尺寸的四种结构中哪种方式的柔轮结构为最优分析模型,分析柔轮各结构参数对柔轮应力的影响。(三)研究的总体安排和进度计划15年第1、2周 毕业实习,提交实习报告、开题报告15年第3、4周 网络搜集相关资料,去图书馆查阅资料,有条件去谐波齿轮减速器工厂参观,确定最终设计方案15年第5、6周 完成文献综述以及外文翻译15年第7、8周 根据工作要求,查阅相关手册,对各部门机构设计、计算;从各方面对产品进行综合评价,校核,修正。15年第911周 提交CAD,设计计算说明书和三维模型,毕业设计初稿15年第12周 提交毕业设计定稿15年第13周 答辩(二)参考文献1 机械设计手册编委会.机械设计手册新版第三卷.北京:机械工业出版社,2004.9.2 齿轮手册编委会.齿轮手册(上册)第2版.北京:机械工业出版社,2002.5.3 辛洪兵. 谐波齿轮传动单极传动比极限的研究. 机械设计. 1998, 1: 1920 4 辛洪兵. 常用柔轮材料的抗断裂性能分析. 长春光学精密机械学院学报.1998, 21(2):6365 5 濮良贵,纪名刚. 机械设计第八版.北京:高等教育出版社,2008.4.5李志刚. 谐波齿轮传动短杯柔轮的有限元分析及结构优化设计研究. 哈尔滨工业大学硕士学位论文. 2008:23246付军锋. 谐波齿轮传动中柔轮应力有限元分析. 西北工业大学硕士学位论文. 2007, 3: 3134 7 张春林,曲继芳.机械创新设计M.北京:高等教育出版社,2008.4.8 陈铁鸣, 王连明, 王黎钦. 机械设计. 哈尔滨工业大学出版社. 2003:122163 9 饶振刚. 行星传动机构设计. 国防工业出版社. 1994:547581 10 饶振刚. 封闭谐波-行星齿轮减速器的设计研究. 传动技术. 2000, 2: 4246 11 姚建初, 陈义保, 周济, 余俊. 齿轮传动啮合效率计算方法的研究. 机械工程学报. 2001, 37(11): 182712 Orlov P.Fundamtls of Machine Design. 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House,1985.毕业设计(论文)题目 谐波齿轮减速器设计及性能仿真 学院 机械设计制造及其自动化专业 学生姓名 学 号 指导教师 系 主 任 二级学院院长 27摘 要 谐波齿轮传动具有体积小、重量轻、结构紧凑、传动比大、效率高等优点。广泛应用于矿山、冶金、飞机、轮船、汽车、起重机、电工机械、仪表、化工业等许多领域谐波齿轮传动有着广泛的发展前景。谐波齿轮减速器与普通减速器相比具有体积小、重量轻、传动平稳、效率高、传动比范围大等优点。但其设计计算较过程复杂,轴承的受力较大、寿命较短。所以对于我们在设计这类减速器时如何进行参数的选择,避免大量繁杂的计算,如何选择好轴承使其使用寿命增加具有一定的设计意义。对谐波减速器国内外的发展现状、优缺点、结构型式和其传动原理进行了一定的阐述。在设计过程当中,对内啮合传动产生的各种干涉进行了详细验算;从如何提高轴承的寿命为出发点,来计算选择减速器齿轮的模数,最终合理设计减速器的整体结构。 关键词:谐波传动;减速器;内齿轮副 Abstract 目 录摘 要IIAbstractIII第1章 绪论51.1 概述51.2谐波齿轮减速器研究内容拟解决的问题51.3 本文研究主要内容6第2章 谐波齿轮减速器设计73.3.1.传动结构形式的选择73.3.2.几何参数的计算73.4 凸轮波发生器及其薄壁轴承的计算83.4.1柔轮齿面的接触强度的计算93.4.2柔轮疲劳强度的计算93.5 轴结构尺寸设计113.6 轴的受力分析及计算113.7 轴承的寿命校核126.2 销轴的强度校核计算146.3 输入轴的强度校核156.4 键的校核计算176.4.1 联轴器处键的校核176.4.2 偏心套处键的校核176.4.3 支座处键的校核176.5 轴承的校核计算18第3章 谐波齿轮减速器三维设计图24总结26致 谢27参考文献28第1章 绪论1.1 概述随着现代工业的高速发展,机械化和自动化水平的不断提高,各工业部门需要大量的减速器,并要求减速器体积小,重量轻,传动比范围大,效率高,承载能力大,运转可靠以及寿命长等。减速器的种类虽然很多,但普通的圆柱齿轮减速器的体积大,结构笨重;普通的蜗轮减速器在大的传动比时,效率较低;摆线针轮行星减速器虽能满足以上提出的要求,但成本较高,需要专用设备制造;而谐波减速器不但基本上能满足以上提出的要求,并可用通用刀具在插齿机上加工,因而成本较低。能适应特种条件下的工作,在国防,冶金,矿山,化工,纺织,食品,轻工,仪表制造,起重运输以及建筑工程等工业部门中取得广泛的应用。1.2谐波齿轮减速器研究内容拟解决的问题谐波传动是五十年代中期出现的一种新型传动,它随着空间技术的发展而迅速发展起来。由于谐波传动具有传动比大、体积小、传动精度高的特点,一开始就被运用在火箭、导弹、卫星等飞行器中,实现了他的优越性。目前这种传动技术已由航天飞行器,飞机中的应用迅速推广到原子能、雷达、通讯、造船、冶金、汽车、坦克、机床、仪表、防止、建筑、起重运输、医疗器械等各个部门。无论是作为数据传递的高精度传动,还是作为传递大转矩的动力传动,都得到了比较满意的效果。特别是,这种传动通过密封壁来传递机械运动,因而它用于操纵高温,高压的管路以及用来驱动工作在高真空,有原子辐射或其他有害介质空间的机构,是现有的其他一切传动所不能比拟的。谐波齿轮传动是五十年代后期随着航天技术发展而出现的一种新型传动。它与一般齿轮传动相比,具有传动比大、体积小、重量轻、精度高、噪音小等优点。此外,它还具有通过密封壳体传递运动和动力的功能,这一特点是机械传动所无法比拟的。谐波齿轮传动一问世,就显示出了它的显著优越性。因此,谐波齿轮传动是一种生命力强、发展前途十分宽广的机械传动。1.3 本文研究主要内容通过利用网络工具、图书馆的书籍和各类期刊、杂志查阅了解谐波减速器的相关知识,确定本设计符合要求,满足需要。具体设计方法如下:1、查阅资料、结合所学专业课程,产生谐波减速器结构设计的基本思路;2、查阅各类机械机构手册,确定合理的谐波减速器结构;3、根据给定技术参数来选择合适的零部件部位;4、重点对驱动机构进行设计研究;5、通过研究国内外情况,确定本设计课题的重点设计;6、完成2D装配图的设计和绘制,并由此绘制零件图;7、编写设计说明书;8、检查并完善本设计课题。本设计采用的方法是理论设计与经验设计相结合的方案,所运用的资料来源广泛,内容充足。第2章 谐波齿轮减速器设计谐波减速器:型号:XB3-50-100额定输出转矩:20N.m 减速比:i1=100 设谐波减速器的的传递效率为:,步进电机应输出力矩为: (3.6)选择BF反应式步进电机型号:55BF003静转矩:0.686N.m步距角:1.53.3.1.传动结构形式的选择该减速器是电传动减速的谐波齿轮装置。要求其传动比较大结构简单紧凑效率较高承载力较高通用性良好。因此本设计方案所选的结构形式为刚轮固定波发生器主动和柔轮从动比较合适。为了便于采用标准刀具来加工柔轮和刚轮,特选取压力角的渐开线齿廓。 3.3.2.几何参数的计算齿数的确定柔轮齿数:刚轮齿数: 已知模数:,则柔轮分度圆直径:钢轮分度圆直径:柔轮齿圈处的厚度:重载时,为了增大柔轮的刚性, 允许将1计算值增加20%,即柔轮筒体壁厚: 为了提高柔轮的刚度,取 轮齿宽度:轮毂凸缘长度:取柔轮筒体长度:轮齿过渡圆角半径:为了减少应力集中,以提高柔轮抗疲劳能力,取由于采用压力角的渐开线齿廓,传动的啮合参数可按考虑到构件柔度的计算公式,即按如下公式进行计算。3.4 凸轮波发生器及其薄壁轴承的计算滚珠直径: 柔轮齿圈处的内径:则:轴承外环厚度:由于工艺上的要求,可将外环做成无滚道的轴承内环厚度: 内环滚道深度:式中的是考虑到外环无滚道而内环滚道加深量。 轴承内外环宽度:所用为滚珠轴承,近似等于齿宽 轴承外环外径: 轴承内环内径:为了便于制造,采用双偏心凸轮波发生器。则凸轮圆弧半径:其中是偏心距:(刚轮分度圆直径,柔轮分度圆直径)则凸轮圆弧半径: 凸轮长半轴:凸轮短半轴:3.4.1柔轮齿面的接触强度的计算根据谐波传动传动比大的特点,其柔轮和刚轮的齿数较多,齿形很接近于直线。故实际谐波齿轮传动的载荷能力主要应由柔轮齿侧工作表面的最大接触应力所限制。因此,谐波齿轮传动的柔轮齿侧面应满足如下接触强度条件:接触强度计算公式: 输出转矩柔轮节圆半径柔轮轮齿宽刚轮压力角接触系数(0.40.9)对于一般双波传动,轮齿宽许用接触应力 则: 所以满足齿面的接触强度要求。3.4.2柔轮疲劳强度的计算 谐波齿轮传动中轮齿的工作特点是:齿面的摩擦滑移接触和柔轮承受着反复的交变载荷。为了使柔轮在循环的弹性变形下能正常工作,除满足耐磨条件外,还必须进行柔轮的疲劳强度计算。柔轮材料采用 调制硬度229269。计算柔轮在反复弹性变形状态下工作时所产生的交变应力幅和平均应力为截面处正应力:切应力:由扭矩产生的剪切应力:其中: 则:验算安全系数:疲劳极限应力:应力安全系数:其中,抗拉屈服极限: 剪切应力集中系数:则满足疲劳强度条件。3.5 轴结构尺寸设计考虑到轴的载荷较大,材料选用45,热处理调质处理,取材料系数 所以,有该轴的最小轴径为: 考虑到键槽的影响,所以dmin取值为17MM,具体结构如下:3.6 轴的受力分析及计算轴的受力模型简化(见图7)及受力计算图 轴的受力分析知: 3.7 轴承的寿命校核鉴于调整间隙的方便,轴承均采用正装.预设轴承寿命为3年即12480h.校核步骤及计算结果见下表:表1 轴承寿命校核步骤及计算结果计算步骤及内容计算结果6014A端B端由手册查出Cr、C0r及e、Y值Cr=98.5kNC0r=86.0kNe=0.68计算比值Fa/FrFaA /FrA e确定X、Y值XA=1 YA =0 查载荷系数fP1.2计算当量载荷P=Fp(XFr+YFa)PA=5796.24 PB=6759.14计算轴承寿命763399h大于12480h由计算结果可见轴承6014AC、6007均合格,最终选用轴承6014。四、轴的强度校核经分析知C、D两处为可能的危险截面, 现来校核这两处的强度:(1)、合成弯矩(2)、扭矩T图(3)、当量弯矩(4)、校核由手册查材料45的强度参数C截面当量弯曲应力:由计算结果可见C截面安全。各轴键、键槽的选择及其校核因减速器中的键联结均为静联结,因此只需进行挤压应力的校核.一、 电机键的选择及校核:带轮处键:按照带轮处的轴径及轴长选 键B8X7,键长50,GB/T1096联结处的材料分别为: 45钢(键) 、40Cr(轴) (1) 刚轮处键: 按照轮毂处的轴径及轴长选 键B14X9GB/T1096联结处的材料分别为: 20Cr (轮毂) 、45钢(键) 、20Cr(轴)此时, 键联结合格.(2)输出轴处键: 按照联轴器处的轴径及轴长选 键16X10,键长100,GB/T1096联结处的材料分别为: 45钢 (联轴器) 、45钢(键) 、45(轴)其中键的强度最低,因此按其许用应力进行校核,查手册其该键联结合格.6.2 销轴的强度校核计算 由于行星轮与内齿轮齿廓曲率半径很接近,齿轮接触面积较大,接触应力小,因此常不计算齿面接触应力。而且在设计齿轮计算齿轮模数时就是应用弯曲应力计算的,固齿轮的齿面弯曲应力是满足的,在此不必在对齿轮进行校核。现对销轴进行校核。 悬臂式销轴的弯曲应力校核公式:式中:制造和安装误差对销轴载荷影响系数 。1.351.5,精度低时取大值,反之取小值,在次取1.35 行星轮对销轴的作用力(上节算得3195.67N)销轴直径(28)许用弯曲应力(销轴的材料为20CrMnMo,根据销轴材料查取150200)L的值从下图11中取得,约为50,则:因此销轴的强度是足够的,其尺寸符合要求。6.3 输入轴的强度校核轴在载荷作用下,将产生弯曲或扭转变形。在进行州的强度校核时,应根据轴的具体受载及应力情况采用相应的计算方法,并恰当的选取许用应力。在此,输入轴受到弯矩和扭矩,按弯扭合成强度条件进行计算,其核算公式为:式中: 轴的计算应力,MPa; 轴所受的弯矩,N; 轴所受的扭矩,N; 轴的抗弯截面系数,; 对称循环变应力时轴的许用弯曲应力。1)做出轴的计算简图(即力学模型)在计算轴所受载荷时,常将轴上的分布载荷简化为集中力,其作用点取为载荷分布段的中点。各支承处所受的反力和应力集中点的反力、转矩都已在图中表示出来了。个支承处与应力集中点之间的距离算得结果在图中也已表明。如图12。2)做出弯矩图轴所受的载荷是从轴上的偏心套传来的,而偏心套所受的力又是行星轮传递的。行星轮所受的力在4.1.1已算出,圆周力为(节圆上)为=5897.78N,径向力为=4931.31N,即为轴所受的力。为了求出各支承处的水平反力和垂直反力列出以下四个个方程:+=5897.78N50100+=4931.31N50100联立以上四个方程可得出:3931.85N,=1965.93N,=3287.54,=1643.77N。弯矩,。总弯矩为3)做出扭矩图传递扭矩T=。扭矩图如图4)校核轴的强度在轴上,偏心套联接处为危险截面(即截面B)如图所示。对轴的抗弯截面系数的计算公式查课本机械设计中表15-4得出。由附图可知d=45,b14,t=5.5,代入数据得出7611.3。在此处的扭转应力为静应力,故取,轴的计算应力:前已选定轴的材料为45钢,调质处理,查课本机械设计中表15-1得出。因此,故安全。图12 输入轴受力分析简图6.4 键的校核计算所用到的三个键都是平键。设计中所涉及的键均为静联结,但有冲击,故用以下公式校核:式中:T为传递转矩(N),k键与轮毂的接触高度(),h为键高();,b为键宽();d为轴径()。查得 ,则校核过程如下:6.4.1 联轴器处键的校核 此处键(C型)传递的转矩为联轴器的转矩,即T=,bhL=10853,l=L-b=43 ,d=35,故有: 故安全6.4.2 偏心套处键的校核 此处键(A型)传递的转矩为输入转矩,即T,bhL=14970,l=L-b=56 ,d=45,故有: 故安全6.4.3 支座处键的校核 此处键(A型)传递的转矩为输出转矩,即TF/21200000N,bhL=161060,l=L-b=44 ,d=53,且采用双键联接,故有: 故安全6.5 轴承的校核计算 根据传动的结构要求选用的轴承如下表7所示:滚动轴承的寿命校核计算公式:式中n 轴承转速,r/min; 轴承寿命指数,对球轴承3,对滚子轴承10/3; 寿命因数,按表7-2-8选取;速度因数,按表7-2-9选取;力矩载荷因数,力矩载荷较小时,较大时,;冲击载荷因数,按表7-2-10选取;温度系数,由于卷扬机长期在室外工作,工作温度小于120,故取。(查表7-2-11)(据机械设计手册第四版第二卷) 。表7 轴承代号及基本参数型号数目基本参数dDB基本额定动载荷/kNGB/T276-199462112551002143.2GB/T276-19946208240801829.5GB/T276-19946220110018034122GB286-813516280140331041)轴承6211(球轴承),与卷筒转速相同,n26.53r/min;查得4.58,=1.073,=1.5,=1.2,则:2)轴承6208(球轴承),与端盖联接的轴承的转速n为输入轴与卷筒的相对速度,故;且查得4.58,=0.324,=1.5,=1.2,则:而与销轴盘联接的轴承的转速与输入轴的转速相同,n960,则:3)轴承6220(球轴承),n26.53r/min;查得4.58,=1.073,=1.5,=1.2,4)轴承3516(滚子轴承),转速n为输入轴与行星轮的相对速度,故;且查得3.93,=0.363,=1.5,=1.2,则: 以上对轴承的校核说明了所选的所有轴承都满足要求。(6)润滑与密封 齿轮的润滑采用浸油润滑,浸油深度为一个齿高,但不小于10mm。 滚动轴承的润滑由于轴承周向速度为1m/s 2m/s,所以选用轴承内充填油脂来润滑。 润滑油的选择齿轮选用普通工业齿轮润滑油,轴承选用钙基润滑脂。 密封方法的选取箱内密封采用挡油盘。箱外密封选用凸缘式轴承盖,在非轴伸端采用闷盖,在轴伸端采用透盖,两者均采用垫片加以密封;此外,对于透盖还需要在轴伸处设置毡圈加以密封。十、箱体尺寸及附件的设计采用HT250铸造而成,其主要结构和尺寸如下:中心距a=154.5mm,取整160mm 总长度L:总宽度B: 总高度H: 箱座壁厚:,未满足要求,直接取8 mm箱盖壁厚:,未满足要求,直接取8mm 箱座凸缘厚度b: =1.5*8=12 mm箱盖凸缘厚度b1: =1.5*8=12mm箱座底凸缘厚度b2:=2.5*8=20 mm箱座肋厚m:=0.85*8=6.8 mm箱盖肋厚m1:=0.85*8=6.8mm扳手空间: C118mm,C216mm轴承座端面外径D2:高速轴上的轴承: 低速轴上的轴承: 轴承旁螺栓间距s:高速轴上的轴承: 低速轴上的轴承: 轴承旁凸台半径R1: 箱体外壁至轴承座端面距离: 地脚螺钉直径: 地脚螺钉数量n:因为a=160mm250mm,所以n=4 轴承旁螺栓直径: 凸缘联接螺栓直径: ,取10mm凸缘联接螺栓间距L:, 取L100mm轴承盖螺钉直径与数量n:高速轴上的轴承:d3=6, n4 低速轴上的轴承: d3=8,n4检查孔盖螺钉直径:,取d46mm检查孔盖螺钉数量n:因为a=160mm3050 ,取 40mm 箱体内壁至箱底距离: 20mm减速器中心高H: ,取H185mm。箱盖外壁圆弧直径R: 箱体内壁至轴承座孔外端面距离L1: 箱体内壁轴向距离L2: 两侧轴承座孔外端面间距离L3: 2、附件的设计(1)检查孔和盖板查机械基础P440表204,取检查孔及其盖板的尺寸为:A115,160,210,260,360,460,取A115mmA195mm,A275mm,B170mm,B90mmd4为M6,数目n4R10h3ABA1B1A2B2hRndL11590957075503104M615(2)通气器选用结构简单的通气螺塞,由机械基础P441表205,取检查孔及其盖板的尺寸为(单位:mm): dDD1SLlaD1M22 1.53225.422291547(3)油面指示器 由机械基础P482附录31,取油标的尺寸为:视孔 A形密封圈规格(4)放油螺塞螺塞的材料使用Q235,用带有细牙螺纹的螺塞拧紧,并在端面接触处增设用耐油橡胶制成的油封圈来保持密封。由机械基础P442表206,取放油螺塞的尺寸如下(单位:mm):dD0LlaDSd1M24 2343116425.42226(5)定位销 定位销直径 ,两个,分别装在箱体的长对角线上。12+1224,取L25mm。(6)起盖螺钉起盖螺钉10mm,两个,长度L箱盖凸缘厚度b1=12mm,取L15mm ,端部制成小圆柱端,不带螺纹,用35钢制造,热处理。(7)起吊装置箱盖上方安装两个吊环螺钉,查机械基础P468附录13,取吊环螺钉尺寸如下(单位:mm):d(D)d1(max)D1(公称)d2(max)h1(max)hd4M89.12021.171836r1r(min)l(公称)a(max)b(max)D2(公称min)h2(公称min)41162.510132.5箱座凸缘的下方铸出吊钩,查机械基础P444表207得,B=C1+C2=18+16=34mmH=0.8B=34*0.8=27.2mmh=0.5H=13.6mmr2 =0.25B=6.8mmb=2 =2*8=16mm第3章 谐波齿轮减速器三维设计图 总结1.谐波减速器与普通相比具有结构紧凑、体积小、重量轻、传动比范围大、效率高、 运转平稳、噪音小、承载能力大结构简单、加工方便、成本低、安装和使用较为方便、运转可靠、使用寿命长等优点。因此,对于研究和开发设计此类减速器有一定的价值。2.在设计减速器过程当中,因内齿轮和外齿轮的齿数差很少,内外齿轮应制成变位齿轮。在选择变位系数时候要充分考虑啮合传动当中的各种干涉问题。我们可以通过试凑法来选取变位系数,但此方法比较繁琐。也可以通过查表法来选择,这种方法简单,在具体的计算验证过程中发现通过查表所得数据,虽满足各种限制条件,却并非最优。所以如何设计出高效的减速器,还有待进一步研究。3.轴承是谐波减速器中的一个薄弱环节,增大齿轮的模数,可以使行星轮的直径增大,可选择较大尺寸的轴承;另外增加两轴承之间的安装距离,使轴承上的载荷减小,因此能使轴承的寿命提高。 致 谢我要感谢我的指导教师XX老师。老师虽身负教学、科研重任,仍抽出时间,不时召集我和同门以督责课业,从初稿到定稿,不厌其烦,一审再审,大到篇章布局的偏颇,小到语句格式的瑕疵,都一一予以指出。是他传授给我方方面面的知识,拓宽了我的知识面,培养了我的功底,对论文的完成不无裨益。我还要感谢学院所有教过我的老师,是你们让我成熟成长;感谢学院的各位工作人员,他细致的工作使我和同学们的学习和生活井然有序。谨向我的父母和家人表示诚挚的谢意。他们是我生命中永远的依靠和支持,他们无微不至的关怀,是我前进的动力;他们的殷殷希望,激发我不断前行。没有他们就没有我,我的点滴成就都来自他们。让我依依不舍的还有各位学友、同门和室友。在我需要帮助的时候他们伸出温暖的双手,鼎立襄助。能和他们相遇、相交、相知是人生的一大幸事。 参考文献1 冯桂安等.机械制造装备设计M. 北京:机械工业出版社,2 齿轮手册编委会.齿轮手册(上册)第2版.北京:机械工业出版社,2002.5.3 渐开线齿轮行星传动的设计与制造编委会. 渐开线齿轮行星传动的设计与制造.北京:机械工业出版社,2002.5.4 陈坐模,葛文杰等. 机械原理第七版.北京:高等教育出版社,2007.12.5 濮良贵,纪名刚. 机械设计第八版.北京:高等教育出版社,2008.4.6 卜炎. 螺纹连接连接设计与计算.北京:高等教育出版社,1993.7 张春林,曲继芳.机械创新设计M.北京:高等教育出版社,2008.4.8 成大先.机械设计手册,第五卷M. 北京:化学工业出版社,9 王昆等.机械设计课程设计M. 北京:高等教育出版社,10 王杰等.机械制造工程学M.北京:北京邮电大学出版社,11 良贵,纪名刚.机械设计M. 北京:机械工业出版社,12 阮忠唐主编. 连轴器,离合器的设计与选用指南M. 13 机械设计手册联合编写组.机械设计手册(上) 14 中国农业机械化科学研究院.实用机械设计手册M.rugged, e generation curr guidelines 2 Power System Network Description bine can enter self-excitation operation. The voltage and fre- quency during off-grid operation are determined by the balance between the systems reactive and real power. Downloaded 28 Mar 2008 to 211.82.100.20. Redistribution subject to ASME license or copyright; see http:/www.asme.org/terms/Terms_Use.cfm We investigate a very simple power system network consisting of one 1.5 MW, fixed-speed wind turbine with an induction gen- erator connected to a line feeder via a transformer H208492 MVA, 3 phase, 60 Hz, 690 V/12 kVH20850. The low-speed shaft operates at 22.5 rpm, and the generator rotor speed is 1200 rpm at its syn- chronous speed. A diagram representing this system is shown in Fig. 1. The power system components analyzed include the following: An infinite bus and a long line connecting the wind turbine to the substation A transformer at the pad mount One potential problem arising from self-excitation is the safety aspect. Because the generator is still generating voltage, it may compromise the safety of the personnel inspecting or repairing the line or generator. Another potential problem is that the generators operating voltage and frequency may vary. Thus, if sensitive equipment is connected to the generator during self-excitation, that equipment may be damaged by over/under voltage and over/ under frequency operation. In spite of the disadvantages of oper- ating the induction generator in self-excitation, some people use this mode for dynamic braking to help control the rotor speed during an emergency such as a grid loss condition. With the proper choice of capacitance and resistor load H20849to dump the energy from the wind turbineH20850, self-excitation can be used to maintain the wind turbine at a safe operating speed during grid loss and me- chanical brake malfunctions. The equations governing the system can be simplified by look- ing at the impedance or admittance of the induction machine. To Contributed by the Solar Energy Division of THE AMERICAN SOCIETY OF MECHANI- CAL ENGINEERS for publication in the ASME JOURNAL OF SOLAR ENERGY ENGINEERING. Manuscript received: February 28, 2005; revised received: July 22, 2005. Associate Editor: Dale Berg. Journal of Solar Energy Engineering NOVEMBER 2005, Vol. 127 / 581Copyright 2005 by ASME E. Muljadi C. P. Butterfield National Renewable Energy Laboratory, Golden, Colorado 80401 H. Romanowitz Oak Creek Energy Systems Inc., Mojave, California 93501 R. Yinger Southern California Edison, Rosemead, California 91770 Self-Excitation Wind Power Traditional wind turbines they are inexpensive, tion generators requir is often used. Because the capacitor compensation among the wind turbine, tant aspects of wind content in the output ena and gives some H20851DOI: 10.1115/1.2047590 1 Introduction Many of todays operating wind turbines have fixed speed in- duction generators that are very reliable, rugged, and low cost. During normal operation, an induction machine requires reactive power from the grid at all times. Thus, the general practice is to compensate reactive power locally at the wind turbine and at the point of common coupling where the wind farm interfaces with the outside world. The most commonly used reactive power com- pensation is capacitor compensation. It is static, low cost, and readily available in different sizes. Different sizes of capacitors are generally needed for different levels of generation. A bank of parallel capacitors is switched in and out to adjust the level of compensation. With proper compensation, the power factor of the wind turbine can be improved significantly, thus improving over- all efficiency and voltage regulation. On the other hand, insuffi- cient reactive power compensation can lead to voltage collapse and instability of the power system, especially in a weak grid environment. Although reactive power compensation can be beneficial to the overall operation of wind turbines, we should be sure the compen- sation is the proper size and provides proper control. Two impor- tant aspects of capacitor compensation, self-excitation H208511,2H20852 and harmonics H208513,4H20852, are the subjects of this paper. In Sec. 2, we describe the power system network; in Sec. 3, we discuss the self-excitation in a fixedspeed wind turbine; and in Sec. 4, we discuss harmonics. Finally, our conclusions are pre- sented in Sec. 5. and Harmonics in Generation are commonly equipped with induction generators because and require very little maintenance. Unfortunately, induc- reactive power from the grid to operate; capacitor compensation the level of required reactive power varies with the output power, must be adjusted as the output power varies. The interactions the power network, and the capacitor compensation are impor- that may result in self-excitation and higher harmonic ent. This paper examines the factors that control these phenom- on how they can be controlled or eliminated. H20852 Capacitors connected in the low voltage side of the trans- former An induction generator For the self-excitation, we focus on the turbine and the capaci- tor compensation only H20849the right half of Fig. 1H20850. For harmonic analysis, we consider the entire network shown in Fig. 1. 3 Self-Excitation 3.1 The Nature of Self-Excitation in an Induction Generator. Self-excitation is a result of the interactions among the induction generator, capacitor compensation, electrical load, and magnetic saturation. This section investigates the self- excitation process in an off-grid induction generator; knowing the limits and the boundaries of self-excitation operation will help us to either utilize or to avoid self-excitation. Fixed capacitors are the most commonly used method of reac- tive power compensation in a fixed-speed wind turbine. An induc- tion generator alone cannot generate its own reactive power; it requires reactive power from the grid to operate normally, and the grid dictates the voltage and frequency of the induction generator. Although self-excitation does not occur during normal grid- connected operation, it can occur during off-grid operation. For example, if a wind turbine operating in normal mode becomes disconnected from the power line due to a sudden fault or distur- bance in the line feeder, the capacitors connected to the induction generator will provide reactive power compensation, and the tur- Downloaded 28 Mar 2008 to 211.82.100.20. Redistribution subject to ASME license or copyright; see http:/www.asme.org/terms/Terms_Use.cfm operate in an isolated fashion, the total admittance of the induc- tion machine and the rest of the connected load must be zero. The voltage of the system is determined by the flux and frequency of the system. Thus, it is easier to start the analysis from a node at one end of the magnetizing branch. Note that the term “imped- ance” in this paper is the conventional impedance divided by the frequency. The term “admittance” in this paper corresponds to the actual admittance multiplied by the frequency. 3.2 Steady-State Representation. The steady-state analysis is important to understand the conditions required to sustain or to diminish self-excitation. As explained above, self-excitation can be a good thing or a bad thing, depending on how we encounter the situation. Figure 2 shows an equivalent circuit of a capacitor- compensated induction generator. As mentioned above, self- excitation operation requires that the balance of both real and reactive power must be maintained. Equation H208491H20850 gives the total admittance of the system shown in Fig. 2: Y S + Y M H11032 + Y R H11032 =0, H208491H20850 where Y S H11005 effective admittance representing the stator winding, the capacitor, and the load seen by node M Y M H11032 H11005 effective admittance representing the magnetizing branch as seen by node M, referred to the stator side Y R H11032 H11005 effective admittance representing the rotor winding as seen by node M, referred to the stator side H20849Note: the superscript “ H11032” indicates that the values are referred to the stator side.H20850 Equation H208491H20850 can be expanded into the equations for imaginary and real parts as shown in Eqs. H208492H20850 and H208493H20850: R 1L /H9275 H20849R 1L /H9275H20850 2 + L 1L 2 + R R H11032/SH9275 H20849R R H11032/SH9275H20850 2 + L LR H11032 2 =0 H208492H20850 where Fig. 1 The physical diagram of the system under investigation Fig. 2 Per phase equivalent circuit of an induction generator under self-excitation mode 582 / Vol. 127, NOVEMBER 2005 1 L M H11032 + L 1L H20849R 1L /H9275H20850 2 + L 1L 2 + L LR H11032 H20849R R H11032/SH9275H20850 2 + L LR H11032 2 =0 H208493H20850 R 1L = R S + R L H20849H9275CR L H20850 2 +1 L 1L = L LS CR L H20849H9275CR L H20850 2 +1 R S H11005 stator winding resistance L LS H11005 stator winding leakage inductance R R H11032 H11005 rotor winding resistance L LR H11032 H11005 rotor winding leakage inductance L M H11032 H11005 stator winding resistance S H11005 operating slip H9275 H11005 operating frequency R L H11005 load resistance connected to the terminals C H11005 capacitor compensation R 1L and L 1L are the effective resistance and inductance, respectively, representing the stator winding and the load as seen by node M. One important aspect of self-excitation is the magnetizing char- acteristic of the induction generator. Figure 3 shows the relation- ship between the flux linkage and the magnetizing inductance for a typical generator; an increase in the flux linkage beyond a cer- tain level reduces the effective magnetizing inductance L M H11032 . This graph can be derived from the experimentally determined no-load characteristic of the induction generator. To solve the above equations, we can fix the capacitor H20849CH20850 and the resistive load H20849R L H20850 values and then find the operating points for different frequencies. From Eq. H208492H20850, we can find the operating slip at a particular frequency. Then, from Eq. H208493H20850, we can find the corresponding magnetizing inductance L M H11032 , and, from Fig. 3, the operating flux linkage at this frequency. The process is repeated for different frequencies. As a base line, we consider a capacitor with a capacitance of 3.8 mF H20849milli-faradH20850 connected to the generator to produce ap- proximately rated VAR H20849volt ampere reactiveH20850 compensation for full load generation H20849high windH20850. A load resistance of R L =1.0 H9024 is used as the base line load. The slip versus rotor speed presented in Fig. 4 shows that the slip is roughly constant throughout the speed range for a constant load resistance. The capacitance does not affect the operating slip for a constant load resistance, but a higher resistance H20849R L high=lower generated powerH20850 corresponds to a lower slip. The voltage at the terminals of the induction generator H20849pre- sented in Fig. 5H20850 shows the impact of changes in the capacitance Fig. 3 A typical magnetization characteristic Transactions of the ASME Downloaded 28 Mar 2008 to 211.82.100.20. Redistribution subject to ASME license or copyright; see http:/www.asme.org/terms/Terms_Use.cfm and load resistance. As shown in Fig. 5, the load resistance does not affect the terminal voltage, especially at the higher rpm H20849higher frequencyH20850, but the capacitance has a significant impact on the voltage profile at the generator terminals. A larger capacitance yields less voltage variation with rotor speed, while a smaller capacitance yields more voltage variation with rotor speed. As shown in Fig. 6, for a given capacitance, changing the effective value of the load resistance can modulate the torque-speed characteristic. These concepts of self-excitation can be exploited to provide dynamic braking for a wind turbine H20849as mentioned aboveH20850 to pre- vent the turbine from running away when it loses its connection to the grid; one simply needs to choose the correct values for capaci- tance H20849a high valueH20850 and load resistance to match the turbine power output. Appropriate operation over a range of wind speeds can be achieved by incorporating a variable resistance and adjust- ing it depending on wind speed. 3.3 Dynamic Behavior. This section examines the transient behavior in self-excitation operation. We choose a value of 3.8 mF capacitance and a load resistance of 1.0 H9024 for this simu- lation. The constant driving torque is set to be 4500 Nm. Note that the wind turbine aerodynamic characteristic and the turbine con- trol system are not included in this simulation because we are more interested in the self-excitation process itself. Thus, we fo- Fig. 4 Variation of slip for a typical self-excited induction generator Fig. 5 Terminal voltage versus rotor speed for different R L and C Journal of Solar Energy Engineering cus on the electrical side of the equations. Figure 7 shows time series of the rotor speed and the electrical output power. In this case, the induction generator starts from rest. The speed increases until it reaches its rated speed. It is initially connected to the grid and at t=3.1 seconds H20849sH20850, the grid is discon- nected and the induction generator enters self-excitation mode. At t=6.375 s, the generator is reconnected to the grid, terminating the self-excitation. The rotor speed increases slightly during self- excitation, but, eventually, the generator torque matches the driv- ing torque H208494500 NmH20850, and the rotor speed is stabilized. When the generator is reconnected to the grid without synchronization, there is a sudden brief transient in the torque as the generator resyn- chronizes with the grid. Once this occurs, the rotor speed settles at the same speed as before the grid disconnection. Figure 8H20849aH20850 plots per phase stator voltage. It shows that the stator voltage is originally the same as the voltage of the grid to which it is connected. During the self-excitation mode H208493.1 sH11021t H110216.375 sH20850, when the rotor speed increases as shown in Fig. 7, the voltage increases and the frequency is a bit higher than 60 Hz. The voltage and the frequency then return to the rated values when the induction generator is reconnected to the grid. Figure 8H20849bH20850 is an expansion of Fig. 8H20849aH20850 between t=3.0 s and t=3.5 s to better illustrate the change in the voltage that occurs during that transient. 4 Harmonic Analysis 4.1 Simplified Per Phase Higher Harmonics Representation. In order to model the harmonic behavior of the network, we replace the power network shown in Fig. 1 with the per phase equivalent circuit shown in Fig. 9H20849aH20850. In this circuit representation, a higher harmonic or multiple of 60 Hz is denoted Fig. 6 The generator torque vs. rotor speed for different R L and C Fig. 7 The generator output power and rotor speed vs. time NOVEMBER 2005, Vol. 127 / 583 4.1.2 Transformer. We consider a three-phase transformer with leakage reactance H20849X xf H20850 of 6 percent. Because the magnetiz- Downloaded 28 Mar 2008 to 211.82.100.20. Redistribution subject to ASME license or copyright; see http:/www.asme.org/terms/Terms_Use.cfm by h, where h is the integer multiple of 60 Hz. Thus h=5 indicates the fifth harmonic H20849300 HzH20850. For wind turbine applications, the induction generator, transformer, and capacitors are three phase and connected in either Wye or Delta configuration, so the even harmonics and the third harmonic do not exist H208515,6H20852. That is, only h=5,7,11,13,17,., etc. exist. 4.1.1 Infinite Bus and Line Feeder. The infinite bus and the line feeder connecting the wind turbine to the substation are rep- resented by a simple Thevenin representation of the larger power system network. Thus, we consider a simple RL line representa- tion. Fig. 8 The terminal voltage versus the time. a Voltage during self-excitation. b Voltage before and during self-excitation, and after reconnection. Fig. 9 The per phase equivalent circuit of the simplified model for harmonic analysis 584 / Vol. 127, NOVEMBER 2005 ing reactance of a large transformer is usually very large com- pared to the leakage reactance H20849X M H11032 H11015H11009 open circuitH20850, only the leakage reactance is considered. Assuming the efficiency of the transformer is about 98 percent at full load, and the copper loss is equal to the core loss H20849a general assumption for an efficient, large transformerH20850, the copper loss and core loss are each approximately 1 percent or 0.01 per unit. With this assumption, we can compute the copper loss in per unit at full load current H20849I 1 FullH6018Load =1.0 per unitH20850, and we can determine the total winding resistance of the primary and secondary winding H20849about one percent in per unitH20850. 4.1.3 Capacitor Compensation. Switched capacitors represent the compensation of the wind turbine. The wind turbine we con- sider is equipped with an additional 1.9 MVAR reactive power compensation H208491.5 MVAR above the 400 kVAR supplied by the manufacturerH20850. The wind turbine is compensated at different levels of compensation depending on the level of generation. The ca- pacitor is represented by the capacitance C in series with the para- sitic resistance H20849R c H20850, representing the losses in the capacitor. This resistance is usually very small for a good quality capacitor. 4.1.4 Induction Generator. The induction generator H208491.5 MW,480 V,60 HzH20850 used for this wind turbine can be repre- sented as the per phase equivalent circuit shown Fig. 9H20849aH20850. The slip of an induction generator at any harmonic frequency h can be modeled as S h = hH9275 s H9275 r hH9275 s H208494H20850 where S h H11005 slip for hth harmonic h H11005 harmonic order H9275 s H11005 synchronous speed of the generator H9275 r H11005 rotor speed of the generator Thus for higher harmonics H20849fifth and higherH20850 the slip is close to 1 H20849S h =1H20850 and for practical purposes is assumed to be 1. 4.2 Steady State Analysis. Figure 9H20849bH20850 shows the simplified equivalent circuit of the interconnected system representing higher harmonics. Note that the magnetizing inductance of the transformers and the induction generator are assumed to be much larger than the leakages and are not included for high harmonic calculations. In this section, we describe the characteristics of the equivalent circuit shown in Fig. 9, examine the impact of varying the capacitor size on the harmonic admittance, and use the result of calculations to explain why harmonic contents of the line cur- rent change as the capacitance is varied. From the superposition theorem, we can analyze a circuit with only one source at a time while the other sources are turned off. For harmonics analysis, the fundamental frequency voltage source can be turned off. In this case, the fundamental frequency voltage source H20849infinite busH20850, V s , is short circuited. Wind farm operator experience shows us that harmonics occur when the transformer operates in the saturation region, that is, at higher flux levels as shown in Fig. 3. During the operation in this saturation region, the resulting current can be distorted into a sharply peaked sinusoidal current due to the larger magnetizing current imbedded in the primary current. This nonsinusoidal cur- rent can excite the network at resonant frequencies of the network. From the circuit diagram we can compute the impedance H20849at any capacitance and harmonic frequencyH20850 seen by the harmonic source, V h , with Eq. H208495H20850, where the sign “ H20648 ” represents the words “in parallel with:” Transactions of the ASME Downloaded 28 Mar 2008 to 211.82.100.20. Redistribution subject to ASME license or copyright; see http:/www.asme.org/terms/Terms_Use.cfm ZH20849C,hH20850 = H20849Z line + 0.5Z xf H20850 H20648 H208490.5Z xf + Z C H20648 Z gen H20850H208495H20850 w
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