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机械类外文翻译译文轴和齿轮的设计及应用

机械类外文翻译译文轴和齿轮的设计及应用
机械类外文翻译译文轴和齿轮的设计及应用

机械类外文翻译—轴和齿轮的设计及应用

摘要

在传统机械和现代机械中齿轮和轴的重要地位是不可动摇的。齿轮和轴主要安装在主轴箱来传递力的方向。通过加工制造它们可以分为许多的型号,分别用于许多的场合。所以我们对齿轮和轴的了解和认识必须是多层次多方位的。

关键词:齿轮;轴

在直齿圆柱齿轮的受力分析中,是假定各力作用在单一平面的。我们将研究作用力具有三维坐标的齿轮。因此,在斜齿轮的情况下,其齿向是不平行于回转轴线的。而在锥齿轮的情况中各回转轴线互相不平行。像我们要讨论的那样,尚有其他道理需要学习,掌握。

斜齿轮用于传递平行轴之间的运动。倾斜角度每个齿轮都一样,但一个必须右旋斜齿,而另一个必须是左旋斜齿。齿的形状是一溅开线螺旋面。如果一张被剪成平行四边形(矩形)的纸张包围在齿轮圆柱体上,纸上印出齿的角刃边就变成斜线。如果我展开这张纸,在血角刃边上的每一个点就发生一渐开线曲线。

直齿圆柱齿轮轮齿的初始接触处是跨过整个齿面而伸展开来的线。斜齿轮轮齿的初始接触是一点,当齿进入更多的啮合时,它就变成线。在直齿圆柱齿轮中,接触是平行于回转轴线的。在斜齿轮中,该先是跨过齿面的对角线。它是齿轮逐渐进行啮合并平稳的从一个齿到另一个齿传递运动,那样就使斜齿轮具有高速重载下平稳传递运动的能力。斜齿轮使轴的轴承承受径向和轴向力。当轴向推力变的大了或由于别的原因而产生某些影响时,那就可以使用人字齿轮。双斜齿轮(人字齿轮)是与反向的并排地装在同一轴上的两个斜齿轮等效。他们产生相反的轴向推力作用,这样就消除了轴向推力。当两个或更多个单向齿斜齿轮被在同一轴上时,齿轮的齿向应作选择,以便产生最小的轴向推力。

交错轴斜齿轮或螺旋齿轮,他们是轴中心线既不相交也不平行。交错轴斜齿轮的齿彼此之间发生点接触,它随着齿轮的磨合而变成线接触。因此他们只能传递小的载荷和主要用于仪器设备中,而且肯定不能推荐在动力传动中使用。交错轴斜齿轮与斜齿轮之间在被安装后互相捏合之前是没有任何区别的。它们是以同样的方法进行制造。一对相啮合的交错轴斜齿轮通常具有同样的齿向,即左旋主动齿轮跟右旋从动齿轮相啮合。在交错轴斜齿设计中,当该齿的斜角相等时所产生滑移速度最小。然而当该齿的斜角不相等时,如果两个齿轮具有相同齿向的话,大斜角齿轮应用作主动齿轮。

蜗轮与交错轴斜齿轮相似。小齿轮即蜗杆具有较小的齿数,通常是一到四齿,由于它们完全缠绕在节圆柱上,因此它们被称为螺纹齿。与其相配的齿轮叫做蜗轮,蜗轮不是真正的斜齿轮。蜗杆和蜗轮通常是用于向垂直相交轴之间的传动提供大的角速度减速比。蜗轮不是斜齿轮,因为其齿顶面做成中凹形状以适配蜗杆曲率,目的是要形成线接触而不是点接触。然而蜗杆蜗轮传动机构中存在齿间有较大滑移速度的缺点,正像交错轴斜齿轮那样。

蜗杆蜗轮机构有单包围和双包围机构。单包围机构就是蜗轮包裹着蜗杆的一种机构。当然,如果每个构件各自局部地包围着对方的蜗轮机构就是双包围蜗轮蜗杆机构。着两者之间的重要区别是,在双包围蜗轮组的轮齿间有面接触,而在单包围的蜗轮组的轮齿间有线接触。一个装置中的蜗杆和蜗轮正像交错轴斜齿轮那样具有相同的齿向,但是其斜齿齿角的角度是极不相同的。蜗杆上的齿斜角度通常很大,而蜗轮上的则极小,因此习惯常规定蜗杆的导角,那就是蜗杆齿斜角的余角;也规定了蜗轮上的齿斜角,该两角之和就等于90度的轴线交角。

当齿轮要用来传递相交轴之间的运动时,就需要某种形式的锥齿轮。虽然锥齿轮通常制造成能构成90度轴交角,但它们也可产生任何角度的轴交角。轮齿可以铸出,铣制或滚切加工。仅就滚齿而言就可达一级精度。在典型的锥齿轮安装中,其中一个锥齿轮常常装于支承的外侧。这意味着轴的挠曲情况更加明显而使在轮齿接触上具有更大的影响。

另外一个难题,发生在难于预示锥齿轮轮齿上的应力,实际上是由于齿轮被加工成锥状造成的。

直齿锥齿轮易于设计且制造简单,如果他们安装的精密而确定,在运转中会产生良好效果。然而在直齿圆柱齿轮情况下,在节线速度较高时,他们将发出噪音。在这些情况下,螺旋锥齿轮比直齿轮能产生平稳的多的啮合作用,因此碰到高速运转的场合那是很有用的。当在汽车的各种不同用途中,有一个带偏心轴的类似锥齿轮的机构,那是常常所希望的。这样的齿轮机构叫做准双曲面齿轮机构,因为它们的节面是双曲回转面。这种齿轮之间的轮齿作用是沿着一根直线上产生滚动与滑动相结合的运动并和蜗轮蜗

杆的轮齿作用有着更多的共同之处。

轴是一种转动或静止的杆件。通常有圆形横截面。在轴上安装像齿轮,皮带轮,飞轮,曲柄,链轮和其他动力传递零件。轴能够承受弯曲,拉伸,压缩或扭转载荷,这些力相结合时,人们期望找到静强度和疲劳强度作为设计的重要依据。因为单根轴可以承受静压力,变应力和交变应力,所有的应力作用都是同时发生的。

“轴”这个词包含着多种含义,例如心轴和主轴。心轴也是轴,既可以旋转也可以静止的轴,但不承受扭转载荷。短的转动轴常常被称为主轴。

当轴的弯曲或扭转变形必需被限制于很小的范围内时,其尺寸应根据变形来确定,然后进行应力分析。因此,如若轴要做得有足够的刚度以致挠曲不太大,那么合应力符合安全要求那是完全可能的。但决不意味着设计者要保证;它们是安全的,轴几乎总是要进行计算的,知道它们是处在可以接受的允许的极限以内。因之,设计者无论何时,动力传递零件,如齿轮或皮带轮都应该设置在靠近支持轴承附近。这就减低了弯矩,因而减小变形和弯曲应力。

虽然来自M.H.G方法在设计轴中难于应用,但它可能用来准确预示实际失效。这样,它是一个检验已经设计好了的轴的或者发现具体轴在运转中发生损坏原因的好方法。进而有着大量的关于设计的问题,其中由于别的考虑例如刚度考虑,尺寸已得到较好的限制。

设计者去查找关于圆角尺寸、热处理、表面光洁度和是否要进行喷丸处理等资料,那真正的唯一的需要是实现所要求的寿命和可靠性。

由于他们的功能相似,将离合器和制动器一起处理。简化摩擦离合器或制动器的动力学表达式中,各自以角速度w1和w2运动的两个转动惯量I1和I2,在制动器情况下其中之一可能是零,由于接上离合器或制动器而最终要导致同样的速度。因为两个构件开始以不同速度运转而使打滑发生了,并且在作用过程中能量散失,结果导致温升。在分析这些装置的性能时,我们应注意到作用力,传递的扭矩,散失的能量和温升。所传递的扭矩关系到作用力,摩擦系数和离合器或制动器的几何状况。这是一个静力学问题。这个问题将必须对每个几何机构形状分别进行研究。然而温升与能量损失有关,研究温升可能与制动器或离合器的类型无关。因为几何形状的重要性是散热表面。各种各样的离合器和制动器可作如下分类:

1.轮缘式内膨胀制冻块;

2.轮缘式外接触制动块;

3.条带式;

4.盘型或轴向式;

5.圆锥型;

6.混合式。

分析摩擦离合器和制动器的各种形式都应用一般的同样的程序,下面的步骤是必需的:

1.假定或确定摩擦表面上压力分布;

2.找出最大压力和任一点处压力之间的关系;

3.应用静平衡条件去找寻(a)作用力;(b)扭矩;(c)支反力。

混合式离合器包括几个类型,例如强制接触离合器、超载释放保护离合器、超越离合器、磁液离合器等等。

强制接触离合器由一个变位杆和两个夹爪组成。各种强制接触离合器之间最大的区别与夹爪的设计有关。为了在结合过程中给变换作用予较长时间周期,夹爪可以是棘轮式的,螺旋型或齿型的。有时使用许多齿或夹爪。他们可能在圆周面上加工齿,以便他们以圆柱周向配合来结合或者在配合元件的端面上加工齿来结合。

虽然强制离合器不像摩擦接触离合器用的那么广泛,但它们确实有很重要的运用。离合器需要同步操作。

有些装置例如线性驱动装置或电机操作螺杆驱动器必须运行到一定的限度然后停

顿下来。为着这些用途就需要超载释放保护离合器。这些离合器通常用弹簧加载,以使得在达到预定的力矩时释放。当到达超载点时听到的“喀嚓”声就被认定为是所希望的信号声。

超越离合器或连轴器允许机器的被动构件“空转”或“超越”,因为主动驱动件停顿了或者因为另一个动力源使被动构件增加了速度。这种离合器通常使用装在外套筒和内轴件之间的滚子或滚珠。该内轴件,在它的周边加工了数个平面。驱动作用是靠在套筒和平面之间契入的滚子来获得。因此该离合器与具有一定数量齿的棘轮棘爪机构等效。

磁液离合器或制动器相对来说是一个新的发展,它们具有两平行的磁极板。这些磁极板之间有磁粉混合物润滑。电磁线圈被装入磁路中的某处。借助激励该线圈,磁液混合物的剪切强度可被精确的控制。这样从充分滑移到完全锁住的任何状态都可以获得。

加工基础

作为产生形状的一种加工方法,机械加工是所有制造过程中最普遍使用的而且是最重要的方法。机械加工过程是一个产生形状的过程,在这过程中,驱动装置使工件上的一些材料以切屑的形式被去除。尽管在某些场合,工件无承受情况下,使用移动式装备来实现加工,但大多数的机械加工是通过既支承工件又支承刀具的装备来完成。

机械加工在知道过程中具备两方面。小批生产低费用。对于铸造、锻造和压力加工,每一个要生产的具体工件形状,即使是一个零件,几乎都要花费高额的加工费用。靠焊

接来产生的结构形状,在很大程度上取决于有效的原材料的形式。一般来说,通过利用贵重设备而又无需特种加工条件下,几乎可以以任何种类原材料开始,借助机械加工把原材料加工成任意所需要的结构形状,只要外部尺寸足够大,那都是可能的。因此对于生产一个零件,甚至当零件结构及要生产的批量大小上按原来都适于用铸造、锻造或者压力加工来生产的,但通常宁可选择机械加工。

严密的精度和良好的表面光洁度,机械加工的第二方面用途是建立在高精度和可能的表面光洁度基础上。许多零件,如果用别的其他方法来生产属于大批量生产的话,那么在机械加工中则是属于低公差且又能满足要求的小批量生产了。另方面,许多零件靠较粗的生产加工工艺提高其一般表面形状,而仅仅是在需要高精度的且选择过的表面才进行机械加工。例如内螺纹,除了机械加工之外,几乎没有别的加工方法能进行加工。又如已锻工件上的小孔加工,也是被锻后紧接着进行机械加工才完成的。

基本的机械加工参数

刀具的基本关系是以以下四个要素来充分描述的:刀具的几何形状,切削速度,进给速度,和吃刀深度。

切削刀具必须用一种合适的材料来制造,它必须是强固、韧性好、坚硬而且耐磨的。刀具的几何形状——以刀尖平面和刀具角为特征——对于每一种切削工艺都必须是正

确的。

切削速度是切削刃通过工件表面的速率,它是以每分钟英寸来表示。为了有效地加工,切削速度高低必须适应特定的工件——刀具配合。一般来说,工件材料越硬,速度越低。

进给速度是刀具切进工件的速度。若工件或刀具作旋转运动,进给量是以每转转过的英寸数目来度量的。当刀具或工件作往复运动时,进给量是以每一行程走过的英寸数度量的。一般来说,在其他条件相同时,进给量与切削速度成反比。

吃刀深度——以英寸计——是刀具进入工件的距离。它等于旋削中的切屑宽度或者等于线性切削中的切屑的厚度。粗加工比起精加工来,吃刀深度较深。

切削参数的改变对切削温度的影响

金属切削操作中,热是在主变形区和副变形区发生的。这结果导致复杂的温度分布遍及刀具、工件和切屑。图中显示了一组典型等温曲线,从中可以看出:像所能预料的那样,当工件材料在主变形区被切削时,沿着整个切屑的宽度上有着很大的温度梯度,而当在副变形区,切屑被切落时,切屑附近的前刀面上就有更高的温度。这导致了前刀面和切屑离切削刃很近的地方切削温度较高。

实质上由于在金属切削中所做的全部功能都被转化为热,那就可以预料:被切离金属的单位体积功率消耗曾家的这些因素就将使切削温度升高。这样刀具前角的增加而所有其他参数不变时,将使切离金属的单位体积所耗功率减小,因而切削温度也将降低。当考虑到未变形切屑厚度增加和切削速度,这情形就更是复杂。未变形切屑厚度的增加趋势必导致通过工件的热的总数上产生比例效应,刀具和切屑仍保持着固定的比例,而切削温度变化倾向于降低。然而切削速度的增加,传导到工件上的热的数量减少而这又增加主变形区中的切屑温升。进而副变形区势必更小,这将在该区内产生升温效应。其他切削参数的变化,实质上对于被切离的单位体积消耗上并没有什么影响,因此实际上对切削温度没有什么作用。因为事实已经表明:切削温度即使有小小的变化对刀具磨损率都将有实质意义的影响作用。这表明如何人从切削参数来确定切削温度那是很合适的。

为着测定高速钢刀具温度的最直接和最精确的方法是W&T法,这方法也就是可提供高速钢刀具温度分布的详细信息的方法。该项技术是建立在高速钢刀具截面金相显微测试基础上,目的是要建立显微结构变化与热变化规律图线关系式。当要加工广泛的工件材料时,Trent已经论述过测定高速钢刀具的切削温度及温度分布的方法。这项技术由于利用电子显微扫描技术已经进一步发展,目的是要研究将已回过火和各种马氏体结构的高速钢再回火引起的微观显微结构变化情况。这项技术亦用于研究高速钢单点车刀和麻花钻的温度分布。

刀具磨损

从已经被处理过的无数脆裂和刃口裂纹的刀具中可知,刀具磨损基本上有三种形式:后刀面磨损,前刀面磨损和V型凹口磨损。后刀面磨损既发生在主刀刃上也发生副刀刃上。关于主刀刃,因其担负切除大部金属切屑任务,这就导致增加切削力和提高切削温度,如果听任而不加以检查处理,那可能导致刀具和工件发生振动且使有效切削的条件可能不再存在。关于副刀刃,那是决定着工件的尺寸和表面光洁度的,后刀面磨损可能造成尺寸不合格的产品而且表面光洁度也差。在大多数实际切削条件下,由于主前刀面先于副前刀面磨损,磨损到达足够大时,刀具将实效,结果是制成不合格零件。

由于刀具表面上的应力分布不均匀,切屑和前刀面之间滑动接触区应力,在滑动接触区的起始处最大,而在接触区的尾部为零,这样磨蚀性磨损在这个区域发生了。这是因为在切削卡住区附近比刀刃附近发生更严重的磨损,而刀刃附近因切屑与前刀面失去接触而磨损较轻。这结果离切削刃一定距离处的前刀面上形成麻点凹坑,这些通常被认为是前刀面的磨损。通常情况下,这磨损横断面是圆弧形的。在许多情况中和对于实际的切削状况而言,前刀面磨损比起后刀面磨损要轻,因此后刀面磨损更普遍地作为刀具失效的尺度标志。然而因许多作者已经表示过的那样在增加切削速度情况下,前刀面上的温度比后刀面上的温度升得更快,而且又因任何形式的磨损率实质上是受到温度变化的重大影响。因此前刀面的磨损通常在高速切削时发生的。

刀具的主后刀面磨损带的尾部是跟未加工过的工件表面相接触,因此后刀面磨损比沿着磨损带末端处更为明显,那是最普通的。这是因为局部效应,这像未加工表面上的已硬化层,这效应是由前面的切削引起的工件硬化造成的。不只是切削,还有像氧化皮,刀刃产生的局部高温也都会引起这种效应。这种局部磨损通常称作为凹坑性磨损,而且偶尔是非常严重的。尽管凹坑的出现对刀具的切削性质无实质意义的影响,但凹坑常常逐渐变深,如果切削在继续进行的话,那么刀具就存在断裂的危机。

如果任何进行性形式的磨损任由继续发展,最终磨损速率明显地增加而刀具将会有摧毁性失效破坏,即刀具将不能再用作切削,造成工件报废,那算是好的,严重的可造成机床破坏。对于各种硬质合金刀具和对于各种类型的磨损,在发生严重失效前,就认为已达到刀具的使用寿命周期的终点。然而对于各种高速钢刀具,其磨损是属于非均匀性磨损,已经发现:当其磨损允许连续甚至到严重失效开始,最有意义的是该刀具可

以获得重磨使用,当然,在实际上,切削时间远比使用到失效的时间短。以下几种现象之一均是刀具严重失效开始的特征:最普遍的是切削力突然增加,在工件上出现烧损环纹和噪音严重增加等。

自动夹具设计

用做装配设备的传统同步夹具把零件移动到夹具中心上,以确保零件从传送机上或从设备盘上取出后置于已定位置上。然而在某些应用场合、强制零件移动到中心线上时,可能引起零件或设备破坏。当零件易损而且小小振动可能导致报废时,或当其位置是由机床主轴或模具来具体时,再或者当公差要求很精密时,那宁可让夹具去适应零件位置,而不是相反。为着这些工作任务,美国俄亥俄州Elyria的Zaytran公司已经开发了一般性功能数据的非同步西类柔顺性夹具。因为夹具作用力和同步化装置是各自独立的,该同步装置可以用精密的滑移装置来替换而不影响夹具作用力。夹具规格范围是从0.2英寸行程,5英镑夹紧力到6英寸行程、400英寸夹紧力。

现代生产的特征是批量变得越来越小而产品的各种规格变化最大。因此,生产的最后阶段,装配因生产计划、批量和产品设计的变更而显得特别脆弱。这种情形正迫使许多公司更多地致力于广泛的合理化改革和前面提到过情况那样装配自动化。尽管柔性夹具的发展很快落后与柔性运输处理装置的发展,如落后于工业机器人的发展,但仍然试图指望增加夹具的柔顺性。事实上夹具的重要的装置——生产装置的专向投资就加强了使夹具更加柔性化在经济上的支持。

根据它们柔顺性,夹具可以分为:专用夹具、组合夹具、标准夹具、高柔性夹具。柔性夹具是以它们对不同工件的高适应性和以少更换低费用为特征的。

结构形式可变换的柔性夹具装有可变更结构排列的零件(例如针形颊板,多片式零件和片状颊板),标准工件的非专用夹持或夹紧元件(例如:启动标准夹持夹具和带有可移动元件的夹具配套件),或者装有陶瓷或硬化了的中介物质(如:流动粒子床夹具和热夹具紧夹具)。为了生产,零件要在夹具中被紧固,需要产生夹紧作用,其有几个与夹具柔顺性无关的步骤:

根据被加工的即基础的部分和工作特点,确定工件在夹具中的所需的位置,接着必须选择若干稳定平面的组合,这些稳定平面就构成工件被固定在夹具中确定位置上的夹持状轮廓结构,均衡所有各力和力矩,而且保证接近工件工作特点。最后,必须计算、调整、组装可拆装的或标准夹具元件的所需位置,以便使工件牢牢地被夹紧在夹具中。依据这样的程序,夹具的轮廓结构和装合的规划和记录过程可以进行自动化控制。

结构造型任务就是要产生若干稳定平面的组合,这样在这些平面上的各夹紧力将使工件和夹具稳定。按惯例,这个任务可用人—机对话即几乎完全自动化的方式来完成。一人—机对话即以自动化方式确定夹具结构造型的优点是可以有组织有规划进行夹具设计,减少所需的设计人员,缩短研究周期和能更好地配置工作条件。简言之,可成功地达到显著提高夹具生产效率和效益。

在充分准备了构造方案和一批材料情况下,在完成首次组装可以成功实现节约时间达60%。

因此夹具机构造型过程的目的是产生合适的编程文件。

Foreign language translation machinery - shaft and gear design and application

Abstract

In the traditional mechanical and modern machinery in the important position of gear and shaft is unshakable. Gears and shafts to the main spindle box installed in the transmission direction of the force. Through the processing can be divided into a number of models were used in many occasions. So we gear and shaft of understanding and knowledge must be multi-level multi-faceted.

Keywords: Gear; axis

In the stress analysis of spur gear, is assumed to act in a single plane. We will study the three-dimensional coordinates of the gear forces. Thus, in the case of helical gears, the teeth are not parallel to the axis of rotation. In the case of bevel gears, the rotational axes are not parallel to each other. As we discussed, there are other reasons to learn and master.

Helical gears are used to pass the motion between parallel axes. Angle of each gear are the same, but one must be right-lateral oblique teeth, while the other must be left-lateral oblique teeth. Tooth shape is a helical surface splash. If one is cut into a parallelogram (rectangle) surrounded by the gear cylinder of paper, the paper printed side edge angle of the tooth becomes slash. If I start this piece of paper, in the blood blade edge angle on each point occurred on the involute curve.

Spur gear teeth is that the initial contacts across the entire tooth surface and extend to the line. Helical gear tooth is the point of initial contact, when the teeth meshing into more, it becomes line. In spur gears, the contact is parallel to the axis of rotation. Helical gears in the first diagonal line across the tooth surface. It is the gradual meshing gears and smooth teeth

from one tooth to another, passing movement that makes high-speed helical gears under heavy load with the ability to transmit motion smoothly. Helical gear shaft bearings to withstand radial and axial force. When the axial thrust of a big change or due to other reasons, have some impact, then you can use the herringbone gear. Double helical gear (herringbone gear) is mounted side by side with the reverse on the same axis is equivalent to two helical gears. They have the opposite effect of axial thrust, thus eliminating axial thrust. When two or more unidirectional bevel gear to be on the same axis, the gear's tooth should be selected so that a minimum of axial thrust.

Crossed helical gears or helical gears, they are neither intersecting nor parallel to the shaft centerline. Crossed helical gears point contact between each other, it's run-in with the gear and into a line contact. So they can only transfer the load and is mainly used for small equipment in, and certainly can not recommend the use of the power transmission. Crossed helical gears and helical gears to be installed between the kneading after each other before, there is no difference. They are manufactured in the same way. A pair of meshing of crossed helical gears typically have the same tooth, that is L-gear driven gear meshing with the right hand. In the crossed helical gear design, when the helix angle equal to the minimum when the sliding velocity generated. However, when the helix angle is not equal, if the two gears with the same tooth, then apply for a large bevel gear gear.

Worm and crossed helical gears similar. The worm pinion has a smaller number of teeth, usually one to four teeth, because they are completely wrapped around the cylindrical section, so they are referred to as thread teeth. Its called the worm gear to match, not a true helical worm gear. Worm and worm gear is usually used to drive between the axis perpendicular to the angular velocity to provide a large reduction ratio. Worm is not a helical gear, because its teeth in the concave top surface made of curvature of the shape to fit the worm, designed to form a line contact rather than point contact. Worm drive mechanism, however there are a large slip velocity between teeth shortcomings, just as crossed helical gears that.

Worm surrounded by a single agency and dual surrounded institutions. Single institution is surrounded by a worm gear worm wrapped body. Of course, if each component to the respective local bodies surrounded by the other side is the double siege worm worm body. The important difference between the two is that in the two-group surrounded the worm gear surface contact between teeth, and in one group of enclosed worm gear between the cable contact. A device in the worm and worm gears just like crossed helical gear that has the same direction, but the angle of helical tooth angle is very different. Oblique angle on the worm gear is usually very big, very small worm is on, so often used the provisions of the worm lead angle, and that is the complementary angle worm gear angle; also provides a worm gear on the bevel of the corners Equal to the sum of the axis angle of 90 degrees.

When the gear to be used to transfer motion between the intersecting axes, we need some form of bevel gear. While the bevel gear is usually manufactured to constitute a shaft angle of 90 degrees, but they also can produce any angle shaft angle. Teeth can be cast out, milling or hobbing system. Hobbing far as to reach an accuracy of terms. Bevel gears in a typical installation, one of the bevel gear is often installed in the outside support. This means that the axis of the deflection becomes even more evident in the tooth contact on leaving a greater impact.

Another problem is difficult to predict in the stress on the bevel gear teeth, in fact, be processed into the gear cone caused.

Straight bevel gears are easy to design and manufacture simple, if they installed sophisticated and determined, in operation will produce good results. However, in the case of spur gears, high speed in the section, they will issue a noise. In these cases, the spiral bevel gear ratio to produce smooth gear meshing and more the role of high-speed operation of the occasion so that encounter is very useful. When a variety of different uses in the car, there is a similar with eccentric shaft bevel gear of the body, it is often desired. This is called the hypoid

gear mechanism gear mechanism, because their surface is curved rotation surface section. The role of gear teeth between the straight line is generated along a combination of rolling and sliding movement and the role and the worm gear has more in common.

Axis is a rotating or stationary bar. Usually have circular cross section. Installed in the shaft as the gears, pulleys, flywheels, cranks, sprockets and other power transmission components. Shaft can withstand bending, tension, compression or torsional loads, the combination of these forces, people expect to find the static strength and fatigue strength as an important basis for the design. Because a single shaft can withstand the static pressure, variable stress and alternating stress, all stress are simultaneous.

"Axis"of the word contains multiple meanings, for example, spindles and spindle. Spindle axis is, either you can still rotate the shaft, but do not bear the torsional load. Short axis of rotation is often called the spindle.

When the axis of bending or torsion deformation must be limited to a small extent, its size should be determined based on deformation and stress analysis. Therefore, should the shaft has sufficient rigidity to be done so that deflection is not too large, then the combined stress meet the safety requirements it is entirely possible. But by no means the designer to ensure that; they are safe, the axis is almost always calculated and what they are in acceptable within the limits allowed. Consequent, the designer at any time, power transmission parts such as gears or pulleys should be set in the near vicinity of support bearing. This reduced the bending moment, thus reducing distortion and bending stress.

Although the method from MHG difficult to use in the design axis, but it may be used to accurately predict the actual failure. Thus, it is a good test shaft has been designed to find specific axis or damaged in the operation because a good way. Thus has a lot of questions about the design, which take into account the other considerations such as stiffness, size restrictions have been better.

Designers to look on the fillet size, heat treatment, surface finish and whether you want to shot peening, etc., that the only real need is to achieve the required service life and reliability.

Because of their similar functions, together with the clutch and brake handle. Simplified kinetic friction clutch or brake expression, each movement with angular velocity w1 and w2 of the two moment of inertia I1 and I2, in case one of the brake may be zero, due to the clutch or brake which ultimately lead to the same Speed. Because the two components operate at different speeds began leaving skid occurs, and in the role of the energy loss process, resulting in temperature rise. In analyzing the performance of these devices, we should note the force, torque transmission, the energy dissipation and temperature rise. The relationship between the torque transfer to the force, friction coefficient and the geometric clutch or brake situation. This is a static problem. This issue will be, respectively, for each geometric shape research institutions. However, the relevant energy losses and temperature rise, temperature rise may be of the type of brake or clutch has nothing to do. Because of the importance of geometry of cooling surface. A variety of clutch and brake can be classified as follows:

1. Inner rim frozen block expansion system;

2. Rim-type brake block outer contact;

3. Striped;

4. Disk type or axial-type;

5. Cone;

6. Hybrid.

Analysis of friction clutches and brakes are applied various forms of the same general procedure, the following steps are required:

1. Assume or determine the pressure distribution on the friction surface;

2. Find the maximum pressure and the pressure at any point between;

3. Application of static equilibrium to find (a) force; (b) torque; (c) support reaction force.

Hybrid clutch includes several types, such as forced exposure to the clutch, overload protection of the clutch release, clutch, magnetic fluid clutch and so on.

Forced contact with the clutch lever and by a modification composed of two jaws. Forced contact with the clutch all the difference between the maximum and the design of the gripper. In order to transform the role of combined process for a long time period, the jaws can be a ratchet, screw type or tooth type. Sometimes using a lot of teeth or jaws. They may face processing in the circular gear to enable them to meet weekly to a cylindrical or in combination with the components of the end face processing gear to combine.

Although the force of friction contact with the clutch with the clutch not so extensive, but they do have very important applications. Need to synchronize the clutch operation.

Some devices such as linear drives, or motor operated screw driver must run to a certain extent and then stalled. To the overloading of the release of these applications need to protect the clutch. The clutch usually spring loaded to achieve the desired torque makes it releases. When you hear when you reach the point of overload, "snip"sound to be identified as the desired signal.

Clutch or coupling of passive components allow the machine to "idle" or "beyond" because the initiative drive stalled pieces because another power source or a passive component to increase speed. The clutch usually installed within the outer sleeve and the hub with roller or ball between. The internal axis pieces, in its processing of a number of surrounding plane. Role is to drive the sleeve and flat against the roller between the need to join to get. Therefore, the clutch and has a certain number of teeth of the ratchet pawl body equivalent.

Magnetic fluid clutch or brake is a relatively new development, they have two parallel magnetic board. The mixture of magnetic powder lubricant between the plates. Electromagnetic coil is loaded into the magnetic circuit somewhere. With incentives in the coil, the shear strength of the magnetic fluid mixtures can be accurately controlled. This full slip to completely locked from any state can get.

Processing based

As a processing method for generating shape, machining https://www.doczj.com/doc/4110267328.html, stable network

Workers in the manufacturing process of all the most commonly used and most important method. Machining process is a process of generating the shape, in this process, the drive to make some material on the workpiece to be removed in the form of chips. Although in some cases, parts not bear the situation, the use of mobile equipment to achieve the processing, but most of the mechanical processing is supported by both the workpiece and the tool support equipment to complete.

Machining process in the know have two aspects. Small batch production of low cost. For casting, forging and pressure processing, each of the specific shape of the workpiece to be produced, even a part, almost always take the high processing costs. By welding to produce the structure and shape to a large extent depend on effective form of raw materials. In general, through the use of expensive equipment, but without special processing conditions, almost any type of raw materials began, with the mechanical processing the raw material into the structure of any of the required shape, as long as the external size is large enough, it is possible. So for the production of a part, even when the components to produce the bulk structure and size are suitable for use according to the original casting, forging or pressure processing to produce, but usually prefer machining.

Strict accuracy and good surface finish, machining of the second use is based on accuracy and surface finish may be the basis. Many parts, if any other part of other methods to produce high-volume production, then in machining is a low tolerance and can meet the requirements of small batch production of the. On the other hand, many parts produced by the coarse surface processing technology to improve their general shape, but simply requires high precision and the surface was chosen to be machined. For example, thread, in addition to mechanical processing, almost no other processing method for processing. Another example

is the blacksmith holes on the processing of documents is carried out immediately after being machined forging only recently completed.

Basic machining parameters

Tool is based on the basic relationship to fully describe the following four elements: the tool geometry, cutting speed, feed rate, and a cutting tool depth.

Cutting tool must be a suitable material to make, it must be strong, good toughness, hard and durable. The geometry of the tool - A tool tip plane and the angle of features - for each of the cutting process must be correct.

Cutting edge cutting speed is the rate through the surface, it is expressed in inches per minute. In order to effectively process, cutting the level must be adapted to the specific workpiece - tool cooperation. In general, the more hard workpiece material, the lower speed.

The tool feed rate is cut into the workpiece speed. If the workpiece or cutting tool rotates, around feed off each inch is the number of metric. When the reciprocating motion of the tool or the workpiece, the feed amount is based on the number of inches of each trip through the

measure. In general, other things being equal, is inversely proportional to feed rate and cutting speed.

Cutting tool depth - in inches - the distance from the tool into the workpiece. It is equal to the width of rotary cutting or chip in the chip is equal to the linear cutting thickness. Roughing to finishing than eating knife deeper depth.

Cutting parameters on cutting temperature

Metal-cutting operations, heat is the main deformation zone and sub-deformation zone to happen. This resulted in a complex temperature distribution throughout the tool, workpiece and chips. The figure shows a typical set of isotherms, from which can be seen: as can be expected, when the workpiece material to be cut in the main deformation zone, the width along the entire chip has a lot on the temperature gradient, and when the Vice-deformation zone, when the chip is cut off, before the knife near the surface of the chip have a higher temperature. This led to the rake face and chip cutting edge away from the vicinity of cutting temperature is higher.

Essentially made in metal cutting due to all the functions have been converted into heat, it can be expected: the metal was cut away from the power consumption per unit volume of these factors has been home to allow cutting temperature. This increase in rake angle and all other parameters constant, will cut the metal away from the power consumption per unit volume decreases, thus cutting temperature will be reduced. When taking into account the increase in the undeformed chip thickness and cutting speed, this situation is even more complicated. Undeformed chip thickness of the upward trend will lead to the adoption of the workpiece to generate heat ratio of the total number of effects, tools and chips remained fixed ratio, and the cutting temperature tends to decrease. However, the increase in cutting speed, the heat conduction to the workpiece, which in turn reduced the number of the main deformation zone increases the temperature rise in the chip. Vice deformation zone and thus

less bound, which will produce heating effects in the region. Changes in the other cutting parameters, in essence, was cut off for unit volume and have little impact on consumption, so in fact there is no effect on the cutting temperature. Due to the fact that: even a small change in temperature, cutting tool wear rate will have a meaningful influence. This shows how the cutting parameters to determine from the cutting temperature is quite appropriate.

High-speed steel cutting tools for the determination of the temperature with the most direct and most accurate way is to W & T method, this method is to provide high-speed steel tool temperature distribution for more information. The technology is based on metallographic cross-section of high speed steel cutting tools on a test basis, the purpose is to create change in microstructure and thermal changes of Chart relationship. When processing a wide range of workpiece material to the time, Trent has been discussed in high-speed steel cutting tool measured temperature and temperature distribution methods. Because this technology has been used scanning electron microscopy further development objective is to study a variety of martensite has been back to the fire and return fire, the structure of the high-speed steel microstructure caused by changes in the microstructure. This technology is also used to study single-point turning and high speed steel twist drill temperature distributions.

Tool wear

Has been treated from many brittle and crack edge tool in the known, there are basically three types of tool wear: flank wear, rake face wear and V-notch wear. Both occurred after the flank wear also occurred on the main blade Vice blade. On the main blade, because the task responsible for removal of most of the metal chips, which leads to increased cutting force and cutting temperature increase, if not allowed to check processing, that may lead to vibration of the tool and the workpiece occurs and the conditions that may no longer be effective cutting Exist. Vice-blade on it is to determine the size and surface finish of the workpiece, the size of

机械设计外文翻译-- 机械加工介绍

毕业论文(设计) 外文翻译 题目:机械加工介绍

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