毕业论文-台式电风扇摇头装置设计.doc

毕业设计说明书 课程名称： 机械设计课程设计 题目名称： 台式电风扇摇头装置 班 级 姓 名： 学 号： 指导教师： 评定成绩：教师评语： 指导老师签名： 20 年 月 日目 录一、设计任务书.2 1、设计题目.2 2、设计要求2 3、功能分解.2 4、机构选用 1.4.1电风扇左右摆头机构 3 1.4.2 电风扇上下仰俯机构 3二、传动方案设计步骤1、左右摆动方案.4 2、上下摆动方案.5 3、最终方案 .5 4、传动比拟定. 6 2.4.1行星轮系设计.6 2.4.2蜗轮蜗杆轮系设计 .7 2.4.3蜗轮蜗杆各参数及强度校核.8 5、机构参数计算. 10三、小结.11四、参考文献.121、 设计任务书1、设计题目设计台式电风扇的摇头机构，使电风扇作摇头动作（在一定的仰角下随摇杆摆动）。风扇的直径为300mm，电扇电动机转速n1450r/min，电扇摇头周期t=10s，电扇摆动角度90、俯仰角度15与急回系数K1.02。风扇可以在一定周期下进行摆头运动，使送风面积增大。2. 设计要求电风扇摇头机构至少包括连杆机构、蜗轮蜗杆机构和齿轮传动机构三种机构。画出机器的运动方案简图与运动循环图。拟订运动循环图时，执行构件的动作起止位置可根据具体情况重叠安排，但必须满足工艺上各个动作的配合，在时间和空间上不能出现干涉。.设计连杆机构，自行确定运动规律，选择连杆机构类型，校核最大压力角。1.2.4设计计算齿轮机构，确定传动比，选择适当的摸数。3. 功能分解电风扇的工作原理是将电风扇的送风区域进行周期性变换，达到增大送风区域的目的。显然，为了完成电风扇的摆头动作，需实现下列运动功能要求：风扇需要按运动规律做左右摆动，因此需要设计相应的摆动机构。风扇需要按路径规律做上下俯仰，因此需要设计相应的俯仰机构。风扇需要转换传动轴线和改变转速，因此需要设计相应的齿轮系机构。对这两个机构的运动功能作进一步分析，可知它们分别应该实现下列基本运动： 左右摆动有三个基本运动：运动轴线变换、传动比降低和周期性摆动。俯仰运动有两个基本运动：运动方向变换和周期性俯仰。转换运动轴线和改变传动比有一个基本动作：运动轴线变换。此外，还要满足传动性能要求：改变电风扇的送风区域时，在急回系数K1.02、摆动角度=90的要求下，尽量保持运动的平稳转换和减小机构间的摩擦。图1.3.1 运动功能图4. 机构选用根据前述要求，电风扇的应作绕一点的往复摆动，且在工作周期中有急回特性。驱动方式为电机驱动，利用机械原理课程设计指导书中第16页中的设计目录，分别选择相应的机构，以实现这三个机构的各项功能，见表一。表一 电风扇摆头的机构选形0功能执行机构工艺动作执行机构设计矩阵左右摆动连杆机构急进急回往复运动齿轮机构连杆机构A1上下摆动连杆机构扇形往复运动连杆机构A21.4.1 电风扇左右摆头机构 考虑到用电动机驱动、而且空间比较狭小，又需要的三个基本动作和高传动比要求。转换运动轴线与改变传动比机构(蜗轮蜗杆与行星轮系组合而成的齿轮箱)a32 和a24。优点是在较小空间内可以运动轴线变换，且有自锁功能。为了能实现上下、左右往复运动，在经济简单的原则下选择双摇杆机构（a43），实现运动方向交替交换。综上，整个电风扇左右摆头机构A1a24，a32，a43。1.4.2 电风扇上下仰俯机构考虑到能实行仰俯运动，事先计划使用（凸轮机构）a11设计仰俯机构，但由于电扇的机壳大小有限，并且凸轮只常使用在低负载的传动过程，假如当电风扇的机头被某重物压住，则很容易损坏凸轮。所以，改变成方案二使用A2=a33（连杆滑块机构）设计。将机壳引出杆使用一条路径导轨进行约束，来完成设想的仰俯运动。二运动方案及选择1、左右摆动方案：图2.1.1 左右摆动方案三机构简图图2.1.2 左右摆动方案三立体图该方案在方案改变了四杆机构的机架及各杆的位置，消除了其自转，达到扇叶随摇杆左右摆动的效果。蜗轮与下面的转盘同轴但可以拉伸，在需要电扇转头时放下蜗轮使其与蜗杆啮合，使蜗杆带动蜗轮转动，带动转头；当不需要转头时，拔起蜗轮即可脱离啮合。2、上下摇摆方案图2.2.1 上下摆动方案立体图 该方案中，导轨来控制风扇机头的上下摇摆，导轨的形状可以根据要求更改来达到不同的上下摇摆效果，并为了美观将导轨藏于机壳内部。 导轨套在主轴上，不随着机头左右转动，而机头在左右转动时其内部的凸起物受导轨轨迹的约束，带动机头在左右转动的同时随导轨轨迹上下摇摆。 本方案不涉及复杂机构，提高了可靠性；上下摇摆轨迹可以随要求改变。3、最终方案： 左右摆动方案三 与 上下摆动的结合。图2.3.1 最终方案三视图四杆长度的定义：首先定义一个摇杆的长度，再由摆角及行程比系数K来估算出曲柄的长度，同时可以由且最短杆为连架杆来辅助估算，再由图5.3.2得到连杆和机架的长度以及最小传动角。表2.3.2序号摇杆长c摆角曲柄长a行程比系数K机架长d连杆长b最小传动角113.10909.21.0269.544170.011138.6894213.50909.21.02161.7053164.005630.3259313.60909.21.02177.6986180.278328.8866413.70909.211.02190.5464193.347027.7623513.71909.211.02191.9816194.806927.6356613.80909.211.02204.4902207.528826.5385713.85909.21.02212.8910216.072425.7894813.90909.21.02219.3212222.611025.2351914.00909.21.02231.7115235.209524.17801014.50909.21.02286.7636291.174919.6662图2.3.3观察表2.3.2，根据实际情况（30CM直径的扇叶），挑出比例最协调的第二组数据，并按比例缩放到c=2.72cm、a=3cm、d=6.56cm、b=6.4cm4传动比设计由于在设计的左右摆头机构中，将蜗轮带动连杆进行整周回转的匀速圆周运动。当蜗轮旋转一周，电扇机壳也正好摇摆一回，得出蜗轮的转速为w=2/10=/5。由于已知条件电动机转速与蜗轮转速相差较大，并且需要改变轴向传动，因此在设计中运用了能产生较大传动比的蜗轮蜗杆机构与行星齿轮机构。最终得出理想的传动比。4.1行星轮系设计行星轮系在一定齿数比的情况下能产生较大的传动比。设计中，采用一对外啮合和一对内啮合齿轮构成。其中Z3为内啮合齿轮，Z1=18，m1=1；Z2=33，m2=1，=17，=1；Z3=68，m3=1。计算得传动比为。图2.4.1 行星轮系4.2蜗轮蜗杆轮系设计与行星轮系配合，并考虑电扇机壳的体积大小，蜗轮蜗杆的尺寸不宜过大。设计中蜗杆的直径为18，m=1.6,=,=；蜗轮的Z=30，m=1.6,=,=，如此，蜗轮蜗杆轮系的传动比i=20，且均为左旋。、将两种轮系组合成一个复合轮系，能顺利地符合设计要求，不仅传动的轴向改变，而且，完成了较大传动比的减速过程，综合两者的传动比，得=。故轴的强度足够。4.3蜗轮蜗杆各参数和校核由于动力的传递方向需要变向，同时也需要将转速降低，所以我们在设计中使用了蜗轮蜗杆减速器。 选择材料：蜗杆用45钢，表面硬度4550HRC。蜗轮材料采用ZCuSn10Pb1，金属型铸造。 4.3.1按接触强度计算 1、确定蜗杆头数、蜗轮齿数 查表知，Z=1 Z=30 2、确定蜗轮转矩 = （=0.82，初估计） =N.mm 3、确定条件 确定载荷系数=1.1, 确定弹性系数 转速系数=0.85 寿命系数=1.13 ，接触系数查图得=2.85 接触疲劳极限由表得，=265MPa，接触强度安全系数=1.34、 初定中心距、模数、导程角 = =29.95 （a取35mm） m=（1.41.7）=1.52.4 取m=1.6 = 0.057 =5、 计算传动效率 当量摩擦角， 啮合效率=0.91, 传动效率=0.98（取=1，因查时考虑轴承的摩擦损耗， =0.98，考虑蜗杆转速较高） 4.3.2 验算齿面接触强度 = =N.mm = =30.335mm(原参数强度足够） 4.3.3 计算传动的主要尺寸 中心距 =38mm 蜗杆的分度圆直径 =28mm， 蜗杆齿顶圆直径 =28+21.6=31.2mm， 蜗杆齿根圆直径 =24.16mm， 蜗杆轴向齿距 =5.024mm， 蜗杆轮齿螺纹部分长度 = =17.81mm（取为20mm）， 蜗轮分度圆直径 =1.630=48mm， 蜗轮齿顶圆直径 =48+21.6=51.2mm， 蜗轮齿根圆直径 =44.16mm， 蜗轮外圆直径 =51.2+1.51.6=53.6mm， 蜗轮轮齿宽度 =15.36mm（取为16mm） 蜗轮齿宽角 =69.5 4.3.4 弯曲强度验算 齿形系数查表得，=2.124，螺旋角系数=0.899 极限弯曲应力查表得，=115MPa 许用弯曲应力 =82MPa（取=1.4） 弯曲应力= = =10.2MPa82MPa（满足要求）5机构参数计算 5.1双摇杆机构设计 因为使用的是以连杆做主动件的双摇杆机构，区别于日常的设计方法，所以，此次设计我们采用一种新的设计思路机架转换法。 机架转换法的理论依据如图所示，图一中的V1是绝对速度，V2是机构运动后，机架相对于摇杆的相对速度，此时V1=V2。然后转换机架，将机架转换至图一中的摇杆位置，现在同一位置处，设定图二中的V1=V2。这样按照图2的机构设计尺寸，所得的尺寸就是实际问题所需要的尺寸长度。此设计，克服了连杆机构以连杆为主动件，连架杆为为从动所产生的难题，通过转换思路，等效运动规律，设计出理想的尺寸长度。三、小结经过1周的机械设计课程设计，让我认识和了解到，机械设计必须认真，细致，不能有任何的马虎。通过1周的学习，也让我系统的复习了机械设计的相关知识，同时也明白了要将理论知识和实践相结合，这样才能真正的掌握知识，提高自己的学习与实践的能力。也通过一步一步的设计，明白了整个过程连接性，需要有个整体的规划才能作好每步的分析，否则一步的脱节或者错误就直接导致走弯路，所作的无用功增加，耗时也随之增加不少。从制定传动方案，合理选择标准部件的类型和型号到计算校核，这一切都是很好的学习过程。也让我的计算机、AutoCAD的综合运用得到了很大的提高。总得来说，收获很大。四、参考文献（1） 裘建新. 机械原理课程设计指导书. 北京 高等教育出版社 2005（2） 申永胜. 机械原理教程（第2版）. 北京 清华大学出版社 2005（3） 孙恒. 机械原理第七版 .高等教育出版社 请您删除一下内容，O(_)O谢谢！Many people have the same mixed feelings when planning a trip during Golden Week. With heaps of time, the seven-day Chinese National Day holiday could be the best occasion to enjoy a destination. However, it can also be the easiest way to ruin how you feel about a place and you may become more fatigued after the holiday, due to battling the large crowds. During peak season, a dream about a place can turn to nightmare without careful planning, especially if you travel with children and older people. As most Chinese people will take the holiday to visit domestic tourist destinations, crowds and busy traffic are inevitable at most places. Also to be expected are increasing transport and accommodation prices, with the possibility that there will be no rooms available. It is also common that youllwait in the line for one hour to get a ticket, and another two hours at the site, to only see a tiny bit of the place due to the crowds. Last year, 428 million tourists traveled in China over the week-long holiday in October. Traveling during this period is a matter that needs thorough preparation. If you are short on time to plan the upcoming Golden Week it may not be a bad idea to avoid some of the most crowded places for now. There is always a place so fascinating that everyone yearns for. Arxan is a place like this. The beauty of Arxan is everlasting regardless of the changing of four seasons. Bestowed by nature, its spectacular seasonal landscape and mountains are just beyond word. Arxan is a crucial destination for the recommended travelling route, China Inner Mongolia Arxan Hailar Manzhouli. It is also the joint of the four prairies across the Sino-Mongolian border, where people gravitate towards the exotic atmosphere mixed with Chinese, Russian, and Mongolia elements. As a historic site for the Yitian Battle, Arxan still embodies the spirit of Genghis Khan. Walking into Arxan, you will be amazed by a kaleidoscope of gorgeous colors all the year round - the Spring azaleas blooming red in the snow, the Summer sea wavering blue in the breeze, the Autumn leaves painted in yellow covering volcanic traces, and the Winter woods shining white on the vast alpine snowscape. Hinggan League Arxan city is situated in the far eastern area of Inner Mongolia Autonomous Region. Its full name Haren Arxan means hot holy water in the Mongolian language. Arxan is a tourism city in the northern frontier with a blend of large forest, grand prairies, vast snowfield, heaven lake cluster, thermium, as well as volcanic cluster. It is a rare and unique ecotourism base filled with healthy sunshine, clean air and unspoiled green. Nestled close to the countrys largest virgin forest, and known for its spring and ecological environment, Arxan is marveled at by many tourists as the purest land on earth. You cannot miss out the Autumn of Arxan. It is definitely the best with brightly-colored scenery full of emotions. Autumn in the northern part of the country comes earlier than the South. A September rain followed by the footprints of Autumn brings more colors to the once emerald green mountain and blooming grassland. Shutterbugs flock to see for themselves the marvel of splendid colors around the mountains and waters, many of whom have travel a long distance and even camp here only to capture a moment of the nature wonder. The silver birch turns golden, while the larch is still proudly green. You will find yourself drowned in the intoxicating red of the wild fruits as well as the glamour of flowers in full blown. And your heart will be lingering on the woods as its time for the wild fruits to ripe. The picturesque Arxan in Autumn is indeed a fairyland only exists in a dream that satisfies all your fantasies. If itrains heavily on Saturday night, some elderly Chinese will say it is because Zhinu, or the Weaving Maid, is crying on the day she met her husband Niulang, or the Cowherd, on the Milky Way. Most Chinese remember being told this romantic tragedy when they were children on Qixi, or the Seventh Night Festival, which falls on the seventh day of the seventh lunar month, which is usually in early August. This year it falls on Saturday, August 2. Folklore Story As the story goes, once there was a cowherd, Niulang, who lived with his elder brother and sister-in-law. But she disliked and abused him, and the boy was forced to leave home with only an old cow for company. The cow, however, was a former god who had violated imperial rules and was sent to earth in bovine form. One day the cow led Niulang to a lake where fairies took a bath on earth. Among them was Zhinu, the most beautiful fairy and a skilled seamstress. The two fell in love at first sight and were soon married. They had a son and daughter and their happy life was held up as an example for hundreds of years in China. Yet in the eyes of the Jade Emperor, the Supreme Deity in Taoism, marriage between a mortal and fairy was strictly forbidden. He ordered the heaven troop to catch Zhinu back. Niulang grew desperate when he discovered Zhinu had been taken back to heaven. Driven by Niulangs misery, the cow told him to turn its hide into a pair of shoes after it died. The magic shoes whisked Niulang, who carried his two children in baskets strung from a shoulder pole, off on a chase after the empress. The pursuit enraged the empress, who took her hairpin and slashed it across the sky creating the Milky Way which separated husband from wife. But all was not lost as magpies, moved by their love and devotion, formed a bridge across the Milky Way to reunite the family. Even the Jade Emperor was touched, and allowed Niulang and Zhinu to meet once a year on the seventh night of the seventh month. This is how Qixi came to be. The festival can be traced back to the Han Dynasty (206 BC-AD 220). Traditionally, people would look up at the sky and find a bright star in the constellation Aquila as well as the star Vega, which are identified as Niulang and Zhinu. The two stars shine on opposite sides of the Milky Way. Customs In bygone days, Qixi was not only a special day for lovers, but also for girls. It is also known as the Begging for Skills Festival or Daughters Festival. In this day, girls will throw a sewing needle into a bowl full of water on the night of Qixi as a test of embroidery skills. If the needle floats on top of the water instead of sinking, it proves the girl is a s