米粉切割机传动及切割部分设计
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黄河科技学院毕业设计(文献翻译) 第 21 页机械传动mechanical drive 机械传动有多种形式,主要可分为两类:靠机件间的摩擦力传递动力和运动的摩擦传动,包括带传动、绳传动和摩擦轮传动等。摩擦传动容易实现无级变速,大都能适应轴间距较大的传动场合,过载打滑还能起到缓冲和保护传动装置的作用,但这种传动一般不能用于大功率的场合,也不能保证准确的传动比。靠主动件与从动件啮合或借助中间件啮合传递动力或运动的啮合传动,包括齿轮传动、链传动、螺旋传动和谐波传动等。啮合传动能够用于大功率的场合,传动比准确,但一般要求较高的制造精度和安装精度。 基本产品分类:减速机、制动器、离合器、连轴器、无级变速机、丝杠、滑轨等 发展历史机械传动机构,可以将动力所提供的运动的方式、方向或速度加以改变,被人们有目的地加以利用。中国古代传动机构类型很多,应用很广,除了上面介绍的以外,像地动仪、鼓风机等等,都是机械传动机构的产物。中国古代传动机构,主要有齿轮传动、绳带传动和链传动。 1、齿轮传动。其出现时间不晚于西汉,西汉时的指南车、记里鼓车,东汉张衡发明的水力天文仪器上,都使用了相当复杂的齿轮传动系统。这些齿轮只用来传递运动,强度要求不高。至于生产上所采用的齿轮,要传递较大的动力,受力一般较大,强度要求较高。古代在利用畜力、水力和风力进行提水、粮食加工等工作时,都要应用此类齿轮。例如在翻车上,须应用一级齿轮传动机构,以改变运动的方位和传递,适应翻车的工作要求。 2、链传动。链,在我国古代出现很早,商代的马具上已有青铜链条,其他青铜器和玉器上也有用链条作为装饰的。西安出土的秦代铜车马上,有十分精美的金属链条。但这都不能算是链传动。作为动力传动的链条,出现在东汉时期。东汉时毕岚率先发明翻车,用以引水。根据其工作原理和运动关系,可以看作是一种链传动。翻车的上、下链轮,一主动,一从动,绕在轮上的翻板就是传动链,这个传动链兼做提水的工作件,因此,翻车是链传动的一种特例。到了宋代,苏颂制造的水运仪象台上,出现了一种“天梯”,实际上是一种铁链条,下横轴通过“天梯”带动上横轴,从而形成了真正的链传动。 3、绳带传动。这是一种利用摩擦力的传动方式。在西汉时,四川出产井盐,在凿井、提水时,都是用牛带动大绳轮,收卷绕过滑轮上的绳索,来提升凿井工具、卤水等。西汉时出现的手摇纺车,是一种典型的绳带传动。在西汉时期的画像石上,有几幅手摇纺车图,可以清楚地看到:大绳轮主动,通过绳索带动纱锭,用手摇大绳轮旋转一周,纱锭旋转几十周,效率很高。以后出现的三锭、五锭的纺车,效率就更高了。元代的水运大纺车,也是用绳带传动的。东汉时,冶金手工业有一项重要发明“水排”,用于鼓风。这种绳带传动的工作原理是:水力推动卧式水轮旋转,水轮轴上装有大绳轮,通过绳带带动小绳轮,小绳轮轴上端曲柄随之旋转,通过连杆推动鼓风器鼓风。这种水排鼓风效力很高,可以抵得上几百匹马鼓风。它的出现,标志着东汉时发达的机械已经在我国出现了,因而意义十分重大。 传动方式分类机械传动按传力方式分,可分为 : 1 摩擦传动。 2 链条传动。 3 齿轮传动。 4 皮带传动。 5 涡轮涡杆传动。 6 棘轮传动。 7 曲轴连杆传动 8 气动传动。 9 液压传动(液压刨) 10 万向节传动 11 钢丝索传动(电梯中应用最广) 12 联轴器传动 13 花键传动。 传动方式详解皮带传动 带传动是具有中间挠性件的传动方式,在机械传动中应用较为普遍,特别是带传动中的V带传动,应用极为广泛。 一、 带传动的类型 带传动是利用带作为中间挠性件来传递运动或动力的一种传动方式。 按传动原理不同,带传动分为摩擦型(平带传动、V带传动等)和啮合型两类。 目前机械设备中应用的带传动以摩擦型带传动居多,下面主要以V带传动为例介绍有关带传动的基本知识。 二、带传动的基本原理 传动带套在主动带轮1和从动带轮2上,对带施加一定的张紧力,带与带轮接触面之间就会产生正压力;主动轮转动时,依靠带和带轮之间的摩擦力来驱动从动轮转动。 带传动的基本原理是依靠带和带轮之间的摩擦力来传递运动和动力。 三、带传动的特点和传动比 1、带传动的特点 由于带富有弹性,并靠摩擦力进行传动,因此它具有结构简单,传动平稳、噪声小,能缓冲吸振,过载时带会在带轮上打滑,对其他零件起过载保护作用,适用于中心距较大的传动等优点。 但带传动也有不少缺点,主要有:不能保证准确的传动比,传动效率低(约为0.900.94),带的使用寿命短,不宜在高温、易燃以及有油和水的场合使用。 2、带传动的传动比 带传动中,主动轮转速 与从动轮转速 之比称为传动比,用符号 表示。 四、常用带传动 常用的带传动有两种形式,即平带传动和V带传动。 1、平带传动 横剖面为扁平矩形,工作是环形内表面与带轮外表面接触。平带传动结构简单,平带较薄,挠曲性和扭转性好,因而适用于高速传动、平行轴间的交叉传动或交错轴间的半交叉传动 2、V带传动 横剖面为等腰梯形,工作时置于带轮槽之中,两侧面接触,产生摩擦力较大,传动能力较强。 五、带传动的张紧装置 带传动工作时,为使带获得所需的张紧力,两带轮的中心距应能调整;带在传动中长期受拉力作用,必然会产生塑性变形而出现松弛现象,使其传动能力下降,因此一般带传动应有张紧装置。带传动的张紧方法主要有调整中心距和使用张紧轮两种,其中它们各自又有定期张紧和自动张紧等不同形式。 六、安装和维护 为提高V带传动的效率,延长V带的使用寿命和确保带传动的正常运转,必须正确做好带传动装置的安装、维修与保养工作。 1、V带必须正确地安装在轮槽之中,一般以带的外边缘与轮缘平齐为准。 2、V带传动中两带轮的轴线要保持平行,且两轮相对应的V形槽的对称平面应重合。 3、拆、装V带时,应先调小两带轮中心距,避免硬撬而损坏V带或设备。套好带后,再将中心距调回到正确位置,带的松紧要适度。 4、V带传动必须安装防护罩,防止因润滑油、切削液或其他杂物等飞溅到V带上而影响传动,并防止伤人事故的发生。 5、对一组V带,损坏时一般要成组更换,新旧带不能混用。 齿轮传动 齿轮传动是由分别安装在主动轴及从动轴上的两个齿轮相互啮合而成。齿轮传动是应用最多的一种传动形式。 一、齿轮传动的基本特点 1、齿轮传递的功率和速度范围很大,功率可从很小到数十万千瓦,圆周速度可从很小到每秒一百多米以上。齿轮尺寸可从小于1mm到大于10m。 2、齿轮传动属于啮合传动,齿轮齿廓为特定曲线,瞬时传动比恒定,且传动平稳、可靠。 3、齿轮传动效率高,使用寿命长。 4、齿轮种类繁多,可以满足各种传动形式的需要。 5、齿轮的制造和安装的精度要求较高。 二、齿轮传动的分类 齿轮的种类很多,可以按不同方法进行分类。 按啮合方式分,齿轮传动有外啮合传动和内啮合传动。 按齿轮的齿向不同分,齿轮传动有直齿圆柱齿轮传动;斜齿圆柱齿轮传动;人字齿圆柱齿轮传动和直齿锥齿轮传动。 三、标准直齿圆柱齿轮传动 直齿圆柱齿轮传动是齿轮传动的最基本形式,它在机械传动装置中应用极为广泛。 齿线为分度圆直母线的圆柱齿轮称为直齿圆柱齿轮,简称直齿轮。 直齿圆柱齿轮的主要参数 (1)齿数z 一个齿轮的轮齿总数称为齿数。 (2)齿形角a 在端平面上,过端面齿廓与分度圆交点处的径向直线与齿廓在该点处的切线所夹的锐角称为齿形角。 标准规定渐开线齿轮的标准齿形角a =20。 (3)模数m 齿距p除以圆周率所得的商称为模数,模数的单位为mm,且已经标准化。 四、其他类型齿轮传动 常用的齿轮传动除直齿圆柱齿轮传动外,还有斜齿圆柱齿轮传动、直齿锥齿轮传动和蜗杆传动等。 1、斜齿圆柱齿轮传动 齿线为螺旋线的圆柱齿轮称为斜齿圆柱齿轮。 斜齿圆柱齿轮根据螺旋角的方向不同,分为左旋齿轮和右旋齿轮两种,其旋向可用右手法则来判断。伸出右手,手掌朝上,四指指向齿轮轴向方向,若齿向与拇指方向一致则为右旋,反之为左旋。 一对斜齿圆柱齿轮啮合时,由于轮齿在圆柱面上是螺旋放置的,所以两啮合轮齿齿面是逐渐接触又逐步脱离的,而一对直齿圆柱齿轮啮合时,两啮合齿齿面是同时在齿向全长上接触,之后又同时脱离。因此,斜齿圆柱齿轮传动平稳性好,冲击小,特别是在高速重载下更为明显。 斜齿圆柱齿轮传动适用于传动平稳性要求高的两平行轴之间的传动。 2、直齿锥齿轮传动 分度曲面为圆锥面的齿轮称为锥齿轮,它是轮齿分布在圆锥面上的齿轮,当其齿向线是分度圆锥面的直母线时称为直齿锥齿轮。 锥齿轮传动用于空间两相交轴之间的传动,一般多用于两轴垂直相交成90的场合。 五、齿轮的失效形式 齿轮在工作过程中由于某种原因而损坏,使其失去正常工作能力的现象称为失效。齿轮的失效形式有很多种,常见的失效形式有: 1、齿面磨损 齿轮在传动过程中,轮齿啮合表面间存在相对滑动。齿轮在受力情况下,齿面间的相对滑动使齿面发生磨损。磨损会破坏齿面形状,造成传动不平稳;另外,磨损使轮齿变薄,造成齿侧间隙增大,轮齿强度降低。齿面磨损是润滑条件差的开式齿轮传动(外露的齿轮传动)的主要失效形式,也是开式蜗杆传动的主要失效形式。 2、轮齿折断 齿轮在工作中,其轮齿的受力状况相当于悬臂梁,齿根处受到的弯矩最大,所产生的应力集中。在啮合过程中,齿轮根部所受的弯矩是交替变化的,因此,在该处最容易产生疲劳裂纹而使轮齿折断,轮齿的这种失效形式称为轮齿的疲劳折断。齿轮的另一种折断是长期过载或受到过大冲击载荷时的突然折断,称为过载折断。 3、轮齿塑性变形 在低速重载的工作条件下,齿轮的齿面承受很大的压力和摩擦力,由于这些力的作用,材料较软的齿轮的局部齿面可能产生塑性流动,使齿面出现凹槽或凸起的棱台,从而破坏齿轮的齿廓形状,使齿轮丧失工作能力。齿轮的这种失效形式称为轮齿的塑性变形。 4、齿面点蚀 齿轮工作时,当啮合表面反复受到接触挤压作用,且由此所产生的压力过大或使用时间过长时,齿面会产生细微的疲劳裂纹。随着齿轮的连续工作,裂纹会沿表层不断扩大,使齿面出现小块金属剥落,形成麻点和斑坑。轮齿齿面发生的这种失效形式称为齿面点蚀。严重的齿面点蚀会破坏齿轮轮齿的工作表面,造成传动不平稳,产生噪声,甚至使齿轮失去工作能力。 齿面点蚀这种失效形式多发生在润滑条件良好的闭式齿轮传动中。 5、齿面胶合 在高速重载的闭式齿轮传动中,齿面润滑较为困难,啮合面在重载作用下产生局部高温使其粘结在一起,当齿轮继续运动时,会在较软的齿面上撕下部分金属材料而出现撕裂沟痕,这种由于齿面粘结和撕裂而造成的失效称为齿面胶合。齿面出现胶合现象后,将严重损坏齿面而导致齿轮失效。闭式蜗杆传动中极易发生这种失效。 链传动 链传动是由两个具有特殊齿形的的齿轮和一条闭合的链条所组成,工作时主动连轮的齿与链条的链节相啮合带动与链条相啮合的从动链轮传动。链条传动主要用于传动比要求较准确,且两轴相距离较远,而且不宜采用齿轮的地方。这就是我们常见的自行车链轮链条传动原理。 一、链传动的特点 1)能保证较精确的传动比(和皮带传动相比较) 2)可以在两轴中心距较远的情况下传递动力(与齿轮传动相比) 3)只能用于平行轴间传动 4)链条磨损后,链节变长,容易产生脱链现象。 二、滚子链 1、滚子链的结构 在机械传动中,常用的传动链是滚子链(也称套筒滚子链)。滚子链由内链板1、外链板2、销轴3、套筒4和滚子5组成。 滚子链的内链板与套筒、外链板与销轴分别采用过盈配合固定,销轴与套筒、滚子与套筒之间分别为间隙配合;各链节可以自由屈伸,滚子与套筒能相对转动。滚子链与链轮啮合时,由于滚子的作用,将套筒与链轮齿直接接触的滑动摩擦转化为滚动摩擦,从而减小了链轮齿的磨损。 滚子链的长度用节数来表示。为了使链条的两端便于连接,链节数应尽量选取偶数,链接头处可用开口销或弹簧夹锁定。当链节数为奇数时,链接头需采用过渡链节,过渡链节不仅制造复杂,而且传递能力低,因此应尽量避免使用。 2、滚子链的标记 滚子链是标准件,其标记为: 链号 排数 整链链节数 标准编号 标记示例 08A188GB/T12431997表示链号为08A(节距为12.70mm),单排,88节的滚子链。 3、链传动的使用 (1)为保证链传动的正常工作,两链轮轴线应相互平行,且两链轮应位于同 一铅垂平面内。 (2)为了提高链传动的质量和使用寿命,应注意进行润滑。 (3)链传动可不施加预紧力,必要时可采用张紧轮装置。 (4)为了安全和防尘,链传动应加装防护罩。 蜗轮蜗杆传动 当一个齿轮具有一个或几个螺旋齿,并且与涡轮(类似于螺旋齿轮)啮合而组成交错轴传动时,这种传动称为蜗杆传动。蜗轮蜗杆传动用于两轴交叉成90度,但彼此既不平行又不相交的情况下,通常在蜗轮传动中,蜗杆是主动件,而蜗轮是被动件。 (1)蜗杆传动的特点 单级传动就能获得很大的传动比,结构紧凑,传动平稳,无噪声,但传动效率低。 (2)蜗杆传动中涡轮转向的判定 蜗杆传动中蜗杆、涡轮转向间的关系取决于两者间的相对位置、蜗杆的旋向及其旋转方向。 判断涡轮相对于蜗杆的转向用左手或右手法则,挡蜗杆为右旋(蜗杆也分左右旋且判断方法与斜齿轮方向判断方法相同)时用右手法则,蜗杆为左旋时用左手法则。弯曲四指,是之指向蜗杆的旋向方向(直箭头表示蜗杆可见侧的圆周运动方向),则拇指的反方向就是涡轮相对于蜗杆的运动方向。 螺旋传动 螺旋传动是利用螺杆和螺母组成的螺旋副来实现传动要求的,主要用于将回转运动变为直线运动,同时传递运动和动力。 螺旋传动的分类: 1)传力螺旋:以传递动力为主,要求以较小的转矩产生较大的轴向推力,用于克服工作阻力。如各种起重或加压装置的螺旋。这种传力螺旋主要是承受很大的轴向力,一般为简写工作,每次工作时间较短,工作速度也不高。email=7&xx/email 2) 传导螺旋:以传递运动为主,有时也承受较大的轴向载荷。如机床进给机构的螺旋等。传导螺旋主要在较长的时间内连续工作,工作速度较高,因此,要求具有较高的传动精度。 3)调整螺旋:以调整、固定零件的相对位置。如机床、仪器、及测试装置中的微调机构的螺旋。调整螺旋不经常转动,一般在空载下调整。 螺旋传动的特点:传动精度高、工作平稳无噪音,易于自锁,能传递较大的动力等特点。 重要性工作机一般都要靠原动机供给一定形式的能量,但是,把原动机和工作机直接连接起来的情况很少,往往需要在二者之间加入传递动力或改变运动状态的传动装置: (1)工作机所需要的速度一般与原动机的最优速度不相符合。 (2)很多工作机都需要根据生产要求进行速度调整,但是依靠原动机的速度来达到这一目的是不经济的,也不可能。 (3)在有些情况下,需要用一台原动机带动若干个工作速度不同的工作机。 (4)为了安全及维护方便,或因机器的外廓尺寸受到限制等原因,不能将原动机和工作机直接连接在一起。 设计概要当设计传动时,如传动的功率、传动比和工作条件已定,则不同的类型传动各有其优缺点。 (1)功率和效率 各类传动所能传递的功率取决于其传动原理、承载能力、载荷分布、工作速度、制造精度、机械效率、发热情况等因素。 效率是评定传动性能的主要指标之一。 (2)速度 速度是传动的主要运动特性之一。提高传动速度是机器的重要发展方向。 (3)外廓尺寸、质量、成本 传动的外廓尺寸和质量与功率和速度的大小密切相关,也与传动零件材料的力学性能有关。mechanical driveMechanical transmission has a variety of forms, can be divided into two categories:1 on parts of the friction between the transmission power and the movement of the friction transmission, including the belt transmission, transmission and friction wheel transmission. Friction transmission easy to realize stepless speed, can adapt to the larger axial spacing transmission occasions, overload slip but also to cushion and protect the drive device, the drive cannot generally be used to big power situation, also cannot ensure accurate transmission ratio. II by active and follower by middleware meshing gears or transfer of power or motion of the meshing transmission, including gear transmission, chain drive, screw drive and harmonic drive. Gear transmission can be used for large power situation, accurate transmission ratio, but generally require a higher precision and installation accuracy.Basic product classification: reducer, brake, clutch, shaft coupling, stepless variable speed machine, screw, such as slideDevelopment historyThe mechanical transmission mechanism, which can drive the power provided by the manner of motion, direction or speed change, people have to use. In ancient China, many types of transmission mechanism, application is very wide, in addition to the outside, like it, blower and so on, is a mechanical transmission mechanism. Chinese ancient transmission mechanism, the main gear transmission, belt transmission and chain transmission.1, gear transmission. The time when the Western Han Dynasty, the car guide, written in drum cart, Zhang Heng of Eastern Han Dynasty invented hydraulic astronomical instruments, using a fairly complex gear transmission system. These gears for transmitting motion, strength requirements is not high. As for the production of the gear, to transfer a larger power, force and generally larger, higher intensity. Ancient in the use of animal power, water and wind power are carrying water, food processing and other work, it can be applied to such gear. For example in a roll-over, requires the use of a gear transmission mechanism, in order to change the moving direction and transfer, to overturn work requirements.2, chain drive. Chain, in our country ancient times occur very early, the harness has bronze chain, other bronzes and jades is also useful as a decorative chain. Xian unearthed Qin copper car right away, have very fine metal chain. But this can not be chain drive. As the power transmission chain, appeared in the Eastern Han dynasty. Bi Lan when the Eastern Han Dynasty the first invention of tipping, for water diversion. According to its working principle and movement relationship, can be regarded as a chain drive. ROPS, sprocket, a driving, a driven, around the wheel of the turning plate is the transmission chain, the transmission chain and make water piece of work, therefore, tipping is a special case of chain drive. The Song Dynasty, Su Song manufacturing waterborne instrument like a table, the emergence of a ladder, is actually an iron chain, under the horizontal axis through the ladder driven on the horizontal axis, thus forming a real chain drive.3, belt drive. This is a use of force transmission. In the Western Han Dynasty, produced in Sichuan salt, in sinking, water, are cattle drive sheave, winding around a pulley on the ropes, to enhance drilling tools, such as brine. When the Western Han Dynasty the hand spinning wheel, is a kind of typical belt transmission. In the period of the Western Han Dynasty portrait stone, have a few hand spinning wheel graph, can see clearly: large rope pulley rope through active, drive spindles, hand rope wheel rotates a circle, a few weeks spindle rotation, the efficiency is very high. After the three spindles, five spindles of spinning wheels, would be more efficient. The waterborne big wheel, also use the rope transmission. When the Eastern Han Dynasty, the metallurgical industry has an important invention water, used for blast. The rope drive working principle is: the hydraulic drive horizontal turbine rotation, water wheel shaft is provided with a large rope pulley drive wheel through a string, string, string shaft is a crank to rotate through the connecting rod, drives air blower blower. This water blast effect is very high, can be worth hundreds of horses blast. It appears, marks the Eastern Han Dynasty developed machinery has appeared in our country, so it is of great significance.Transmission mode classificationMechanical transmission by way of power transmission points, can be divided into:1friction drive.2chain drive.3gear transmission.4 belt drive.5turbine bar transmission.6wheel drive.7 crankshaft connecting rod driveThe 8 pneumatic transmission.9hydraulic ( hydraulic plane )10universal joint drive11wire transmission ( elevator in the most widely used )The 12coupling transmission13spline drive.Transmission mode.Belt driveBelt drive is a middle flexible part of the transmission mode, in the mechanical transmission is widely used, especially in the belt drive V belt transmission, is widely used.One, belt type transmissionBelt drive is used as a middle flexible part with to transfer movement and power of a transmission mode.According to the transmission principle of different, belt drive for friction type ( flat belt, V belt transmission etc.) and meshing type two class.The mechanical equipment in the application of the belt to the friction belt transmission are, deals with the V belt as an example to introduce the basic knowledge of the belt drive.Two, the basic principle of belt transmissionThe drive belt is sheathed on the driving belt wheel 1and the driven belt wheel 2, on the band exerts certain tension force, belt and belt wheel between the contact surface will produce positive pressure; the driving wheel to rotate, depends on the friction between the belt and belt wheel to drive the driven wheel to rotate.Belt transmission is the basic principle of relying on the friction between the belt and the belt wheel to transfer movement and power.Three, belt transmission characteristics and transmission ratio1, belt transmission characteristicsAs with elastic, and rely on friction transmission, so it has the advantages of simple structure, stable transmission, small noise, can buffer the vibration absorption, overload belt on the belt wheel slip, on the other part has the function of overload protection, suitable for center distance larger transmission etc.But the belt drive also has many disadvantages, mainly include: cannot ensure accurate transmission ratio, transmission efficiency is low ( approximately 0.90to 0.94), with a short service life, not in high temperature, flammable and have the oil and water use.2, belt drive transmission ratioBelt drive, the speed of the driving gear and the driven wheel speed is called the gear ratio, represented by the symbol.Four, commonly used in belt transmissionCommonly used belt transmission has two forms, namely flat belt drive and V belt transmission.1, flat belt driveThe cross section of a flat rectangular, work is an annular inner surface and the outer surface is in contact with wheel. Flat belt drive belt has the advantages of simple structure, thin, bending and torsion is good, so it is suitable for high speed transmission, parallel to the axis of the drive shaft between the cross or cross half cross driveIn 2, V belt transmissionCross section is an isosceles trapezoid, work on the belt wheel groove, both sides contact, frictional force is larger, transmission ability.Five, belt tensioning deviceBelt transmission, in order to make access to the tensioning force, two wheel center distance can be adjusted; band in the transmission long are subjected to a tensile force, is bound to produce plastic deformation and relaxation phenomena, so that the transmission capacity decreased, so the general belt proper tensioning device. Belt tensioning method are mainly used for adjusting the center distance and tensioning wheel two, wherein each of them has periodically tensioning and automatic tension in different forms.In six, the installation and maintenanceIn order to improve the V belt transmission efficiency, prolong the service life of the band V and ensure the normal operation of belt drive, must make correct belt drive device installation, repair and maintenance work.In 1, V must be installed correctly in the round grooves, generally to the outer edge of the belt and the rim flush.In 2, V in belt transmission wheel axis to maintain two parallel, and two corresponding to the V shaped slot symmetry plane should be coincident.3, assembly and disassembly, V belt, should adjust two wheel center distance, to avoid a hard prying and damaged V belt or device. A good band, the center distance is adjusted to return to the correct position, the elastic to moderate.In 4, V belts must be installed protective cover, to prevent lubricating oil, cutting fluid or other debris flying to the V take affect the transmission, and prevent hurt accidents.In 5, a group of V belt, damage to grouping replacement, new band not mix.Gear driveGear is respectively arranged on the driving shaft and the driven shaft and two gear are engaged with each other. Gear transmission was the most used form of a transmission.One, the basic characteristic of gear transmission1, gear transmission power and the speed of a large area, the power can be from small to Shushiwanqian tile, circumferential velocity can be from very small to more than 100meters per second. Gear size from less than 1mm to more than 10m.In 2, belongs to the meshing transmission gear, gear tooth profile for a specific curve, instantaneous transmission ratio constant, stable transmission, reliable.In 3, a gear transmission with high efficiency, long service life.In 4, a gear range, can meet a variety of transmission form need.In 5, the gear manufacturing and installation of high precision.In two, the classification of gear transmissionGear type are many, can be classified according to different method to classify.According to the meshing points, gear transmission with outer meshing transmission and internal gear transmission.According to gear tooth to different points, gear with straight tooth cylindrical gears; helical gear; herringbone gear with straight tooth bevel gear drive.Three, standard spur gear transmissionStraight tooth cylindrical gear drive gear drive are the most basic form of mechanical transmission device, it is widely applied in the.Tooth line as the pitch circle straight generatrix cylindrical gear called straight tooth cylindrical gear, referred to as the spur gear.The main parameters of spur gear(1) the number Z of teeth of a gear tooth number number is called.(2) the profile angle of aIn the end plane, end surface tooth profile with the pitch circle at the intersection of the radial line and profile in the point of the tangent between acute angle is called the profile angle.Standard involute gear tooth profile of the standard angle a = 20degrees.(3) the modulus MPitch P divided by PI gains business called modulus, modulus unit is the mm, and have been standardized.Four, other types of gear transmissionIn addition to commonly used gear transmission spur gear transmission, and helical gear, straight bevel gear and worm drive.1, cylindrical helical gear driveDentate line for helical cylindrical gear called helical cylindrical gear.Cylindrical helical gear with helix angle in different directions, divided into left and right gear two gear, the rotating direction by the right hand rule to judge. Stretched out his right hand, palm up, four fingers are pointing to gear axial direction, if the tooth and the direction is right handed, and vice versa for L.A pair of helical gears meshing, the tooth in a cylindrical surface is spiral placed, so the two meshing gear tooth surface is gradually exposed gradually disengaged, and a pair of straight tooth cylindrical gear, two gear tooth surface is at the same time in the tooth length of exposure, and then at the same time out. Therefore, helical cylindrical gear drive is of good stability, small impact, especially in high speed and heavy load is more obviously.Helical cylindrical gear transmission for smooth transmission of high requirements for the two parallel to the axis of the transmission between.In 2, straight bevel gear driveDividing surface is a circular conical surface gear called bevel gear tooth, it is distributed on the cone gear, when the tooth line is a straight line reference cone surface called straight bevel gear.Bevel gear drive for the space between two intersecting axes drive, more generally used two perpendicular axes intersect at an angle of 90 degrees.In five, the failure forms of gearGear in the work process for some reason and damage, which lost its normal working ability of the phenomenon
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