可任意分度的插齿机齿轮加工回转工作台的设计【含CAD图纸和说明书】
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可任意分度的插齿机齿轮加工回转工作台的设计the design of gear processing rotary table on random indexing gear shaper 摘要插齿机作为齿轮加工机床的一种，已逐步体现出其加工的优越性，在滚齿机、铣齿机上无法加工的一些齿轮，如双联齿轮和内齿轮，在插齿机上可加工制造出来。在本课题的设计中，采用步进电机控制回转工作台的转角。在单片机的控制下，步进电机每秒钟发出的脉冲数决定了工作台的转位角度，使该插齿机成为真正意义上的可任意分度加工，进而可实现加工任意齿数的齿轮。本课题所设计的回转工作台是用单片机作为控制系统来控制步进电机的转速，动力由步进电机发出，通过齿轮传动和蜗轮蜗杆传动，将动力传递到蜗轮上，蜗轮的转动再带动主轴转动，从而实现与主轴夹紧的工件的转动。所设计的回转工作台实用、简单、可靠、效率高。关键词 步进电机；回转工作台；单片机；任意分度AbstractAs one kind of the gear finishing lathes, the gear shaper has manifested the superiority in processing gradually, on the gear-hobbing machine, the gear cutter cannt be true, for exampl- e,the twin gear and the annular gear, but they can be processed on the gear shaper. In this design, I use a step-by-step the electrical machinery to control the corner of rotary table. Under the control of monolithic integrated circuit, the number of pulse of the step-by-step electrical machinery each second can be sent out to decide the rotary tables indexing angle, making the gear shaper to become the random indexing processing in the true sense .And then, the gear processing which is mentioned willfully might be realized.The rotary table designed in this topic is controled by the monolithic integrated circuit to control the rotational speed of step-by-step electrical machinery, the step-by-step electrical machinery send out the power firstly, through the gear drive and the worm gear worm drive, then the power is transmisted to worm gear , and worm gear-rotating makes the main axle rotate the same time, and then,it comes to be realized that the work piece clamped with main axle come to rotate.In my opinion，this design of the rotary table is practical, simple, reliable, and the efficiency is high.Keywords step-by-step the electrical machinery the rotary table the monolithic integrated circuit random indexingI目 录1 绪论11.1 本课题的背景及应解决的主要问题11.2 本课题的研究目的和现实意义11.3 插齿概述21.4 插齿机类型与适用范围21.4.1 插齿机类型21.4.2 各种插齿机的适用范围31.5插齿机的工作原理及其参数31.5.1 插齿机的外观图31.5.2 插齿机的工作原理41.5.3 插齿机的参数52 设计方案选择62.1 分度工作台62.2 数控回转工作台62.2.1 开环数控转台62.2.2 闭环数控回转工作台73 工作台设计83.1 步进电机的选择与控制83.1.1 步进电动机的特点与种类83.1.2 步进电动机的选择93.1.3 步进电动机的控制93.2 蜗轮蜗杆设计计算143.2.1 蜗杆传动输入参数143.2.2 接触疲劳强度计算153.2.3 确定蜗轮蜗杆的主要尺寸163.2.4 确定蜗轮蜗杆的传动效率163.2.5 选择蜗轮蜗杆的精度等级173.2.6 蜗轮蜗杆传动的热平衡计算173.3 齿轮设计计算183.3.1 齿轮设计输入参数183.3.2 齿轮的材料及热处理183.3.3 齿轮的基本参数183.3.4 齿面接触疲劳强度校核203.3.5 齿根弯曲强度校核213.4 轴承设计计算213.4.1 轴承方案选择213.4.2 轴承动载荷和寿命计算223.5 箱体设计计算234 控制系统设计244.1 单片机244.2 驱动电路的设计244.3 电源电路设计254.4 程序设计26结论32致谢33参考文献34附录35附录135附录242461 绪论1.1本课题的背景及应解决的主要问题齿轮是重要的基础传动元件。近年来，随着技术的发展，尽管采用电气、液压传动装置日益增多，对齿轮的需求仍有增无减。目前，中国齿轮市场的年销售额超过了800亿元。而齿轮加工机床也是结构复杂、制造难度大的机床产品之一。世界进入20世纪，齿轮的需求量迅速增长，从而促进了齿轮加工机床的开发和生产。20世纪70年代以后，由于现代机械设备的功率、速度、噪声与结构尺寸等工作参数的提高，以及对加工可靠性的进一步要求，目前齿轮装置的制造精度和内在质量都提高了。齿轮加工技术在高精度、高效率、自动化和柔性化等方面提出更高的要求。当前齿轮机床的发展趋势是：提高精度；提高刚度；提高效率；应用数控技术增加柔性和扩展工艺性能。插齿机作为齿轮加工机床的一种，已逐步体现出其加工的特殊性，在滚齿机、铣齿机上无法加工的一些齿轮，如双联齿轮和内齿轮，在插齿机上可加工制造出来。为了插齿机工作的可靠性、工艺适应性，增强机床的柔性和自动化程度、简化机械传动结构，特别是为满足一些特殊齿轮加工需要，如各种非圆异形的内啮合齿轮加工，国外先进工业国家的插齿机产品早在80年代末就已全部数控化，近年来我国已开发了不同品种的数控插齿机，推向市场，逐步向机电一体化产品发展。在保证产品质量的前提下,如何扩大插齿机的加工范围和降低制造成本是提高产品竞争力的关键所在。产品成本一般包括原材料、工具损耗、机床折旧、工人工资等各项管理费用。他们与劳动生产效率密切相关,因此,扩大机床加工范围,提高产品加工效率是降低产品成本的有效途径。1.2本课题的研究目的和现实意义在本课题的设计中，采用步进电机控制回转工作台的转角。在单片机的控制下，步进电机每秒钟发出的脉冲数决定了工作台的转位角度，使该插齿机成为真正意义上的可任意分度加工，进而可实现加工任意齿数的齿轮。为了扩大插齿机的加工性能，适应某些齿轮加工的需要，插齿机的进给运动，除了X、Y、Z三个坐标轴的直线进给运动之外，还可以绕X、Y、Z三个坐标轴的圆周进给运动，分别称A、B、C轴。插齿机的圆周进给运动，一般由回转工作台来实现。插齿机除了可以实现圆周进给运动之外，还可以完成分度运动，一次装夹即可多次加工，大大提高生产率。一般插齿机等加工设备都配有回转工作台等标准附件。标准附件的普通回转工作台不能调整中心,使用很不方便,在操作过程中必须把中心与回转工作台中心重合装夹后,才能进行加工。若如工件有多个中心位置需要加工,一次装夹就无法完成。只能是逐个装夹、调整和加工,这样做使安装和调整的时间大幅度增加,不但影响了加工的效率,也降低了工件的加工精度,增加产品的制造成本。本课题设计的回转工作台，在加工多个中心的工件时,显示出它的优越性,调整中心十分方便,省去了多次找正、调整和装夹的麻烦。由于一次装夹后实现了多个中心位置的加工,明显地减少了因多次调整安装所造成的积累误差,所加工零件的尺寸精度比原先有大幅度的提高,工效提高3倍以上。1.3插齿概述插齿加工（如图1-1所示）是由插齿刀具与工件齿轮之间作无间隙的啮合运动，插齿刀具作往复运动，并绕本身轴线转动，在展成运动中加工出工件齿形。插齿是广泛采用的切齿方法，用形状为齿轮或齿条的插齿刀具，与被加工齿轮按一定的速比作啮合运动的同时，刀具沿齿宽方向作往复运动形成切削加工。插齿运动包括：往复运动、圆周运动、径向进给运动、分度运动和让刀运动。插齿，能加工滚齿、铣齿等无法加工的一些齿轮，如双联齿轮和内齿轮。插齿方法最常见的是用齿轮型插齿刀插齿，其次是用齿条型插齿刀插齿。以上两种方法为滚切法，此外还有成形法插齿。图1-1 插齿刀和插齿运动1插齿刀 2齿坯1.4插齿机类型与适用范围1.4.1插齿机类型插齿机按其工件轴线的空间位置分为立式插齿机和卧式插齿机。立式插齿机又可分为工件（工作台）让刀和插齿刀（刀架）让刀两种。卧式插齿机又可分为单插齿刀和双插齿刀两种。卧式插齿机的刀具轴线与工件主轴轴线是水平布置的。插齿机按其刀具形状分为齿条刀插齿机和圆盘刀插齿机两种型式。齿条刀插齿机也分立式和卧式两种。立式齿条刀插齿机以一把齿条刀作为切削工具；卧式齿条刀插齿机以两把齿条刀作为切削工具。齿条刀插齿机的生产厂家为数不多，主要以瑞士马格公司为代表，绝大多数厂家都生产圆盘刀插齿机。目前生产和使用得最多的是立式插齿机。立式插齿机与卧式插齿机的加工原理是相同的，但结构形式差别很大。1.4.2各种插齿机的适用范围插齿是加工范围最广的制齿方法之一。和滚齿机一样，插齿机加工也采用展成原理，但插齿的主运动采用往复运动形式，因此圆盘插齿刀轴不仅可在工件的外部加工外齿轮，也可伸入到工件的内部加工内齿轮；由于插齿刀切出工件端面只需很小的空间，所以它是加工台阶齿轮双联或多联齿轮的主要方法；此外，它还是目前加工齿条、尤其是7级精度以上齿条的最重要的方法。但是，当用圆盘刀加工斜齿轮时，相应于每一种螺旋角和旋向的斜齿轮需要一特定的斜齿插齿刀，并且在一般情况下，还需要设计专用的插斜齿附件螺旋导轨。齿条刀插齿机加工外齿轮时，由于齿条刀的长度有限，当插销到一定齿数时工件必须自动退回到原始位置，同时完成分齿动作，因而滚切过程不是连续的，而是周期性的。用同一把齿条刀既可加工直齿又可加工斜齿，但螺旋角越大，刀具切出时需要的空间越大。齿条刀插齿机只有一对分度蜗轮副，并且齿条刀形状简单容易达到高精度，所以加工精度较圆盘刀插齿机高。特别是当切制大模数大直径的外齿轮时，齿条刀插齿机的刀架和齿条刀的刚性都可得到加强，因而可获得较高的加工精度和生产率。圆盘刀插齿机主要用于加工内、外啮合直齿圆柱齿轮，当刀架换装上螺旋导轨时，还可以加工相应的斜齿圆柱齿轮。特别适宜于加工带有台阶的双联或多联齿轮。如采用特殊刀具和专用附件时，可加工各种多边轮廓的工件：无声链轮、棘轮、内外花键、齿形带轮、扇形齿轮、非完整齿齿轮和特殊齿形的离合器、齿条、端面齿轮和锥齿轮等。1.5插齿机的工作原理及其参数1.5.1插齿机的外观图插齿机的外观立体图如图1-2所示。图1-2 插齿机的外观立体图1插齿刀 2刀架 3横梁 4工件 5工作台 6床身1.5.2插齿机的工作原理插齿加工按展成原理滚切法。插销过程如同一对齿轮作无间隙的啮合运转，其中一个是工件，另一个是特殊的齿轮（插齿刀）。插齿刀本身如同一个修正齿轮，它在磨损后可重复刃磨使用。插齿刀的模数和压力角必须与被加工齿轮的模数和压力角相等，当用圆盘刀插销斜齿轮时两者的螺旋角必须相等，加工外齿轮时两者螺旋方向相反；加工内齿轮时两者螺旋方向相同。插齿刀每个刀齿的渐开线齿廓和齿顶都做出刀刃：一个顶刃和两个侧刃，它们有前角和后角。为了在切削时实现滚切过程，插齿刀和齿坯（工件）按不同的方向各绕其本身的轴线回转，它们的相互关系见式（1.1）： n/n0=z0/z 式（1.1）式中 n工件转速； no插齿刀转速； z工件齿数； z0插齿刀齿数。滚切运动是形成工件渐开线齿廓所必须的，插齿刀轴的上下往复运动（主运动）形成齿线。此外，整个加工过程还需要插齿刀相对于工件作径向进给（切入）运动。这个运动根据具体情况可分为一次至多次进行。若采用一次进给，则一次进给到全齿深时为止。此后插齿刀与工件继续对滚，当工件转过一整转时，全部轮齿切到全齿深，加工结束。刀架或工作台退出并回到原始位置。通常，插齿刀轴向下运动为工作行程，向上运动为空行程。滚切运动、进给运动和刀轴往复运动同时进行，为了避免插齿刀刮伤已加工的工件表面，在插齿刀空回行程时，插齿刀相对于工件还必须有一个让刀运动，而在工作行程开始时插齿刀（或工件）必须回复到原来的位置。1.5.3插齿机的参数插齿机的主要联系尺寸如图1-3所示，机床的参数应符合表1-1 的规定。图1-3 插齿机主要机床尺寸表 1-1最大工件直径D mm200320500（800）1250（2000）3150最大模数m mm4681216最大加工齿宽B mm5070100160240插齿刀主轴轴颈D mm31.74331.74331.74331.74380锥孔莫氏三号1：20插齿刀孔径d2 mm6080100180240T型槽槽数44816槽宽 mm12142236注1.括号内参数主要用于变型产品。2.当D=1250mm时，刀轴应增加轴颈直径为88.9mm、101.6mm的接套； 当D=3150mm时，刀轴应增加轴颈直径为31.743mm、889mm、101.6mm的接套2设计方案选择回转工作台是插齿机不可缺少的重要附件。它的作用是按照控制装置的信号或指令作回转分度或连续作回转进给运动，以使插齿机能完成指定的加工工序。常用的回转工作台有分度工作台和数控回转工作台。2.1 分度工作台分度工作台的功能是完成回转分度运动，即按照控制系统的指令，在需要分度时，将工作台及其工作台回转一定角度。其作用是在加工中自动完成工作的转位换面，实现工件一次安装完成几个面的加工。按照采用的定位元件的不同，有定位销式分度工作台和鼠牙盘式分度工作台。分度工作台通常由于结构的关系，仅能作规定好的度数的分度运动，不能连续旋转运动。机床的分度结构，它本身很难保证工作台的分度的高精度的要求不适合本设计要求。2.2 数控回转工作台数控回转工作台的功用有：（1）使工作台进行圆周进给完成切削工作；（2）使工作台进行分度工作。它按照控制系统的指令，在需要时候完成任务。其作用是既能作为数控机床的一个回转坐标轴，用于加工直线、曲线、圆弧或与直线坐标轴联动加工曲面，又能作为分度头完成工作的转位换面。这正式本设计所需要的。再看数控回转工作台与分度工作台的区别，数控回转工作台，从外形上看，与分度工作台没有什么区别，但在结构上有以下一系列特点，现就开环数控工作台和闭环数控工作台分述如下：2.2.1 开环数控转台开环系统数控转台是由传动系统、间隙消除装置及蜗轮夹紧装置等组成。数控转台一般由电液脉冲马达或功率步进电机驱动，当接到控制系统的回转指令后，首先要把蜗轮松开，然后开动电液脉冲马达，按照指令脉冲来确定工作台回转的方向、回转的速度快慢、回转的角度大小以及回转过程中速度的变化等参数。当回转工作台回转完毕后，再把蜗轮夹紧恢复到原来的位置。数控转台的分度定位是按控制系统所指定的脉冲数来决定转位角度的，没有其他的定位元件。因此，对开环数控转台的传动精度要求高，传动间隙应尽量小。数控回转工作台既没有鼠牙盘，也没有定位销，它的定位精度完全是由控制系统来决定的。因此，对于开环系统的数控回转工作台，要求它的传动系统中没有间隙，否则在反向时产生传动误差而影响定位精度。当工作台静止时，必须处于锁紧状态。为此，在蜗轮底部的辐射方向装有八对夹紧瓦，并在底座上均布同样数量的小液压缸。当小液压缸的上腔接通压力油时，活塞便压向钢球，撑开夹紧瓦，并夹紧蜗轮。在工作台需要回转时，先使小液压缸的上腔接通回油路，在弹簧的作用下，钢球抬起，夹紧瓦将蜗轮松开。回转工作台的导轨面由大型滚动轴承支承，并由圆锥滚柱轴承及双列向心圆柱滚子轴承保持准确的回转中心。数控回转工作台的定位精度主要取决于蜗杆副的传动精度，因而必须采用高精度蜗杆副。在半闭环控制系统中，可以在实际测量工作台静态定位误差之后，确定需要补偿角度的位置和补偿的值，记忆在补偿回路中，由数控装置进行误差补偿。在全闭环控制系统中，由高精度的圆光栅发出工作台精确到位信号，反馈给数控装置进行控制。回转工作台设有零点，当它作回零运动时，先用挡铁压下限位开关，使工作台降速，然后由圆光栅或编码器发出零位信号，使工作台准确地停在零位。数控回转工作台可以作任意角度的回转和分度，也可以作连续回转进给运动。这种数控回转工作台的驱动采用开环系统，其定位精度主要取决于蜗杆蜗轮的运动精度，虽然采用高精度的五级蜗杆蜗轮副，但还是不能满足机床的定位精度。因此还需要借助于数控装置进行误差补偿。回转工作台的导轨面是由大型滚柱轴承支承，径向又有圆锥滚子轴承及双列向心圆柱滚子轴承保证回转平稳，并有上述强力夹紧机构。因此回转工作台的刚度很好。2.2.2 闭环数控回转工作台闭环数控回转工作台一般采用直流或交流伺服电机驱动，其结构与开环数控转台大致相同。区别在于：闭环数控回转工作台有角度测量元件（圆光栅或圆感应同步器）。所测量的结果反馈与指令进行比较，按闭环原理进行工作，使回转工作台定位精度更高。总结，对以上三种方案进行分析，它们各有优缺点，为了达到设计要求，我选择开环数控回转工作台。另外，为了消除蜗轮副的传动间隙，采用双导程蜗杆，通过移动蜗杆的轴向位置来调整间隙。在此设计中将采用此结构来控制工作台绕Z轴的转动，采用步进电机驱动，通过变速齿轮和蜗杆传递动力给大蜗轮，从而带动附加工作台在Z轴方向的旋转。3工作台设计3.1 步进电机的选择与控制3.1.1 步进电动机的特点与种类3.1.1.1 步进电动机的特点步进电动机又称为脉冲电动机。它是将电脉冲信号转换成机械角位移的执行元件。其输入一个电脉冲就转动一步，既每当电动机的绕组接受一个电脉冲，转子就转过一个相应的步距角。转子角位移的大小及转速分别与输入的电脉冲数与频率成正比，并在时间上与输入脉冲同步，只要控制输入电脉冲的数量，频率以及电动机绕组的通电顺序，电动机即可获得所需的转角，转速及转向，很容易用微机实现数字控制。步进电动机具有以下主要特点：（1）步进电动机的工作状态不易受各种干扰因素（如电源电压的波动，电流的大小与波形的变化，温度等）的影响，只要在他们的大小未引起步进电动机产生“丢失”现象之前，就不会影响其正常工作；（2）步进电动机的步距角有误差，转子转过一定的步数以后也会出现累计误差，但转子转过一转之后，其累计误差就会变为“零”，因此不会长期积累；（3）控制性能好，在启动、停止、反转时不易“丢失”。因此，步进电动机被广泛应用于开环控制的机电一体化系统，使系统简化，并可靠的获得较高的位置精度。3.1.1.2 步进电动机的种类步进电动机的种类很多,有旋转式步进电动机,也有直线步进电动机;从励磁相数来分有三相,四相,五相,六相等步进电动机.就常用的旋转式步进电动机的转子结构来说,可将其分为一下三种:（1）可变磁阻型(VR-Variable Reluctance) 该类电动机由定子绕组产生的反应电磁力吸引用软磁钢制成的齿形转子作步进驱动,故又称作反应式步进电动机,其结构原理为:其定子与转子由铁心构成,没有永久磁铁,定子上嵌有线圈,转子朝定子与转子之间磁阻最小方向转动,并由此而得名可变磁阻型.这类电动机的转子结构简单,转子直径小，有利于高速下的响应.由于VR型步进电动机的铁心无极性,故不需要改变电流极性,为此多为单极性励磁.该类电动机的定子与转子均不含永久磁铁,故无励磁时没有保持力.另外,需要将气隙做得尽可能小,例如几个微米.这种电动机具有制造成本高,效率低,转子的阻尼差,噪声大等缺点.（2）永磁型(PM-Permanent Magner)PM型步进电动机的转子采用永久磁铁,定子采用软磁钢制成,绕组轮流通电,建立的磁场与永久磁铁的恒定磁场相互吸引与排斥产生转矩,这种电动机采用了永久磁铁,即使定子绕组断电也能保持一定转矩,故具有记忆能力,可用作定位驱动.PM型电动机的特点是励磁功率小,效率高,造价便宜,但由于转子磁铁的磁化间距受到限制,难于制造,故步距角较大.（3）混合型(HB-Hybrid)这种电动机转子上嵌有永久磁铁,故可以说是永磁型步进电动机,但从定子和转子的导磁体来看,又和可变磁组型相似,所以是永磁型和可变磁组型相结合的一种形式,故称为混合型步进电动机,它不仅具有VR型步进电动机步矩角小,响应频率高的优点,而且还具有PM型步进电动机励磁功率小,效率高的优点.它的定子与VR型没有多大的差别,只是在相数和绕组接线方面有其特殊的地方,例如,VR型一般都作成集中绕组的形式,每极上放有一套绕组,相对的两极为一相,而HB型步进电动机的定子绕组大多数为四相,而且每极同时绕两相绕组或采用桥式电路绕一相绕组,按正反脉冲供电.这种类型的电动机由转子铁心的凸极数和定子的副凸极数决定步距角的大小,可制造出步距角较小的电动机.永久磁铁也可磁化轴向的两极,可使用轴向各向异性磁铁制成高效电动机.3.1.2 步进电动机的选择本设计选用反应式步进电动机，其技术性能数据如下：型号： 75BF001相数： 3步距角： 1.5/电压: 24V相电流: 3A最大静转矩 : 0.392（N.M）空载起动频率: 1750步/S电感: 19mH电阻: 0.62分配方式: 三相六拍外形尺寸: 75x53(6)转子动惯量： 1.274重量： 1.1（Kg）3.1.3 步进电动机的控制控制步进电动机的运行速度实际上就是控制系统发出CP脉冲的频率或者是换相的周期,系统可用两种办法来确定CP脉冲的周期,一种是延时,一种是定时器.（1）延时方法这种方法是在每次换相后,调用一个延时子程序,待延时结束后再次执行换相子程序,延时子程序的延时时间与换相子程序所用的时间的和就是CP脉冲的周期.例如:SV:LCALL CW; 正转一步 LCALL OS; 调用延时子程序 SJMP SV; 返回继续（2）定时器方法AT89S51芯片内部有两个定时器,都是可编程的利用定时器的定时功能就可以产生任意周期的定时信号,从而可以方便地控制系统输出CP脉冲周期.我们将电动机的换相子程序放在定时器中断服务程序中则定时器中断一次电动机就换相一次,从而实现对电动机的速度控制,在本设计中,电动机的驱动频率是每秒2500步(2500PPS),则周期为400s.计算装载初值: X=FE70H由于从定时器申请中断到系统响应中断,再到中断服务程序中对定时器进行装载,都需要花费一定的时间,这个时间形成附加延时,为实现精确定时,应将这个时间计算在内。下面的程序定时器需要7个机器周期,因此先把FE7OH加上7后得FE77H作为装载值先存在中间单元R6、R7中,R6存77H，R7存FEH。程序如下：SPD：MOV R6，#77H MOV R7，#FEH LCALL CW CLR TR0 MOVA， TL0 ADDA，R6 MOV TL0，A MOVA，TH0 ADDA，R7 MOV TH0，A SETB TR0RET1系统在反复执行这个中断程序时，所产生的驱动步进电动机的时钟脉冲就是恒定的频率。而且与设定值之间不存在误差。程序如下：（所列出的程序均通过编译） ORG 0000H AJMP MAINORG 000BHLJMP SPDORG 001BHLJMP DISBUFFORG 0040HMAIN： MOV SP，#60H MOV TMOD，#O1H MOV TCON，#01H MOVRO,#8 MOV SCON,#00H MOV TL1,#00H MOV TH1,#00H SETB TR1PRO: LCALL KEY1 LCALL KP SJMP PR0SPD: MOV R6,#1FH MOV R7,#0FCH LCALL CW LCALL DISBUFF LCALL DISP CLR TR0 MOV A, TL0 ADD A, R6 MOV TL0,A MOV A,TH0 ADD A,R7 MOV TH0,A SETB TR0 RET1KEY1: ACALL KSY1 JNZ LK1 AJMP KEY1LK1: ACALL TRMS ACALL KS1 JNZ LK2 AJMP KEY1LK2: MOV R2,#0FEH MOV R4,#00HLK4: MOV DPTR,#7FFCH MOV A,R2 MOVX DPTR,A INC DPTR INC DPTR MOVX A,DPTR JB ACC.0,LONE MOV A,#00H AJMP LKPLTWO: JB ACC.2,LTHR MOV A,#16H AJMP LKPLTHR: JB ACC.3,NEXT MOV A,#24HLKP: ADD A,R4 PUSH ACCLK3: ACALL KS1 JNZ LK3 POP ACC RETNEXT: INC R4 MOV A,R2 JNB ACC.7,KND RL A MOV R2,A AJMP LK4KND: AJMP KEY1KS1: MOV DPTR,#7FFCH MOV A,#00H MOVX DPTR,A INC DPTR INC DPTR MOVX A,DPTR CPL A ANL A,#0FH RETTRMS: MOV R7,#18HTM: MOV R6,#0FFHTM6: DJMZ R6,TM6 DJMZ R7TM RETKP: MOV R3,A RL A ADD A,R2 MOV DPTR,#JPTAB JMP A+DPTRJPTAB:LJMP SPD RETCW: INC R0 CJNE R0,#8,CW1 MOV RO,#0CW1: MOV A,RO MOV DPTR,#7FFOH MOVC A,A+DPTR MOV DPTR,#7FF0H MOVX DPTR,A RETDISBUFF:MOV R5,#15 DJNZ R5,T1S MOV R1,#30H MOV R1,AT1S: MOV TL1,#00H MOV TH1,#00H SETB TR1 RET1DISP: SETB P1.0 MOV R7,#4 MOV R1,#30HDISP0: MOV A,R1 MOV DPTR,#6000H MOVC A,A+DPTR MOV SBUF,ADISP1: JNB T1,DISP1 CLR T1 INC R1 DJNZ R7,DISP0 CLR P1.0 RETORG 6000HDB 0C0H,OF9H,0F9H,0A0H,0B0H,99HDB 92H,82H,0F8H,80H,98HORG 7FF0HDB 01H,03H,02H,06H,04H,0CH,08H,09HEND3.2 蜗轮蜗杆设计计算3.2.1 蜗杆传动输入参数蜗杆传递功率P: 0.7KW蜗杆转速n1: 800r/min传动比i12： 50传动比误差： 0.00% 预定寿命H: 24000h 阿基米德类型蜗杆工作载荷平稳；单向工作；长期连续工作；喷油润滑方式，润滑情况良好；自然通风冷却方式。 3.2.2 接触疲劳强度计算材料及热处理蜗杆蜗轮材料：查机械设计手册表5-127，蜗杆：45，表面渗碳淬火，HRC 4555查机械设计手册表5-128，蜗轮：ZQSn10-1,金属模铸造，选定蜗杆头数Z1和蜗轮齿数Z2 Z1=1 所以： Z2=80确定接触许用应力H查机械设计手册表5-128 H=200MP蜗轮轴转矩T2 式（3.1）确定模数mt及蜗杆直径系数q 式（3.2） K=1.1由机械设计手册表5-119得： q=10确定蜗杆螺旋升角由机械设计手册表5-121得： 确定中心距a 式（3.3）蜗杆蜗轮弯曲强度校核许用弯曲强度查机械设计手册表5-128得： =70MP蜗轮当量齿数Z 式（3.4）蜗轮齿形系数YF2查机械设计手册表5-129得：YF2=1.41弯曲强度校核 式（3.5）所以强度够。3.2.3确定蜗轮蜗杆的主要尺寸分度圆直径d 式（3.6）齿顶圆直径da查机械设计手册表5-142得：ha=3mm所以： 式（3.7）齿根圆直径df查机械设计手册表5-142得：hf=4mm所以：蜗杆螺纹长度L 式（3.8）蜗轮外径de2 式（3.9）蜗轮宽度b b=1*da1=1*48=48mm 式（3.10）轴向齿距极限累积误差轴向齿距极限偏差蜗杆齿形公差、蜗杆螺牙跳动公差分别为蜗杆法向弦齿高和弦齿厚查机械设计手册表5-142得：3.2.4 确定蜗轮蜗杆的传动效率因为本设计中采用闭式蜗杆传动，其传动效率的计算公式为： 式（3.11）因为是蜗杆主动，所以啮合效率按下式计算： 式（3.12）该式中：蜗杆分度圆螺旋升角； 为当量摩擦角，查机械设计手册表5-130得：取所以，搅油损失的效率，通常取=0.98轴承的效率，对滚动轴承常取=0.99所以，蜗杆的传动效率为：3.2.5 选择蜗轮蜗杆的精度等级本设计中，蜗杆蜗轮都选择的是7级精度。3.2.6 蜗轮蜗杆传动的热平衡计算该工作台采用自然通风冷却方式，因此箱体表面散出的热量折合的功率为： 式（3.13）导热系数，常取传动装置的散热面积A: 式（3.14）A1为内面被油浸溅着而外面又被自然循环的空气所冷却的箱壳的面积，A2为A1计算表面的补强筋和凸座的表面以及安装在金属底座或机械框架上的箱壳底面积。所以估算出：达到热平衡时，传动的发热率应和箱体的散热率相等，依热平衡条件得： 式（3.15）式中 P1蜗杆轴功率；润滑油的温度，对蜗杆传动可以允许到95度，这里取30度；周围空气的温度，一般取20度。综合以上数据，可以得出箱体表面散出的热量估算为： 式（3.16）可以满足工作台的正常工作需要。3.3齿轮设计计算3.3.1 齿轮设计输入参数传递功率： P=0.98 kw齿轮1的转速： n1=1500r/min齿轮2的转速： n2=800 r/min传动比： i=1500/800=1.875预定寿命： H=24000 h原动机载荷特性： 均匀平稳工作机载荷特性： 均匀平稳3.3.2 齿轮的材料及热处理齿面类型：软齿面热处理质量要求级别： MQ（1）材料及热处理：齿轮1：查机械设计手册表5-78，齿轮1选择材料为 45钢；热处理方式为调质处理。硬度范围为：HB240-270本设计取硬度为： HB250齿轮2：为了提高齿轮的抗胶合性能，大齿轮和小齿轮应选择不同牌号的钢来制造,根据这个原则，查机械设计手册表5-78齿轮2 选择的材料为40Cr；热处理为调质处理。硬度范围为：HB200-230 所以本设计选用硬度为：HB215（2）机械性能：齿轮1： 查机械设计手册表5-78得： 许用接触强度极限应力： 许用弯曲强度极限应力： 齿轮2： 查机械设计手册表5-78得： 许用接触强度极限应力： 许用弯曲强度极限应力： 3.3.3 齿轮的基本参数模数m的选取，取模数为 m=2齿数Z1、Z2的确定，取齿数为 Z1=24所以 变位系数X： 由于齿轮有偏心调节环约束，所以取变位系数 x=0，总变位系数 齿轮主要尺寸： 分度圆直径： 式（3.17） 齿顶圆直径： 取 所以 式（3.18） 齿根圆直径： 式（3.19） 基圆直径：取标准值为 节圆直径： 标准中心距a: 式（3.20） 中心距变动系数y：y=-0.001 齿高变动系数为0.001小齿轮齿宽B： 式（3.21） 因取值为1，所以B=48mm 分度圆弦齿厚和弦齿高： 查机械设计手册表5-57得： 对齿轮1： 对齿轮2： 固定弦齿厚和固定弦齿高： 查表机械设计手册表5-58得： 公法线跨齿数K和公法线长度： 对齿轮1： K=3 对齿轮2： K=5 3.3.4齿面接触疲劳强度校核有关参数和系数的确定确定圆周力Ft 式（3.22）因 式（3.23）所以 式（3.24）查机械设计手册表5-74得：，因此所以按V=，查机械设计手册表5-82选齿轮的精度为7级；重合度的计算，重合度可由下公式算出：因 所以 所以 查机械设计手册图5-26得：由于齿轮对称轴承布置，查机械设计手册图5-24得：查机械设计手册表5-75得：查机械设计手册图5-24得：核算齿面接触疲劳强度 式（3.25）因已知：许用接触疲劳强度，所以接触强度足够。3.3.5齿根弯曲强度校核确定有关参数和系数 与接触强度相同；查图机械设计手册图5-29得：齿形系数 查图机械设计手册图5-30得：重合度系数因为是直齿圆柱齿轮，所以螺旋角系数核算齿根弯曲强度 式（3.26）因许用齿根弯曲强度，所以，齿跟弯曲强度足够。34 轴承的设计3.4.1轴承方案的选择（1）方案1：两端单向固定常用于跨距L400 mm的情况，支点常采用两端单向固定的方式，每个轴承分别承受一个方向的轴向力。（2）方案2：一端双向固定， 一端游动 为保证滚动轴承系能正常传递轴向力且不发生窜动，在轴上各零件定位固定的基础上，必须合理设计轴系支点的轴向固定结构。轴上同时受径向和轴向联合载荷，一般选用角接触轴承或圆锥滚子轴承。 但圆锥滚子轴承能同时受径向和单向轴向载荷、承载能力，成对使用。 角接触轴承能同时受径向载荷和单向轴向载荷，由于角接触轴承受径向载荷会产生相应的附加力，故应成对使用。为保证滚动轴承能正常传递轴向力且不发生窜动，在轴上各零件定位固定的基础上，还要设计轴承的组合。当轴较长或工作温度较高时，轴的热膨胀伸缩量大，宜采用一端双向固定，一端游动的支点结构。综合考虑本设计，方案1较适合。3.4.2轴承的动载荷和寿命计算由上面所知径向力F=150N，F=15N根据机械设计手册表18.7查取滚动轴承当量动载荷计算的X,Y值为X=1,Y=0冲击载荷系数fd:考虑到是轻微冲击,查机械设计手册表18.8取=1.2当量动载荷: P=f=1.2(150+0)=180N式（3.27） L=1.510h 式（3.28） 该联结为受拉紧联结。有公式: 式（3.29）式中 螺栓总拉力；螺栓的预紧力；工作载荷；剩余预紧力；螺栓的相对刚度系数；下列数据可供选择时参考: 无变化时, =(0.20.6)；有变化时, =(0.61.0)；因为=100N,所以=(0.61.0)=(60100)N，即=100+100=200N强度校核公式: 式（3.30） 在这里选螺栓的材料为40Cr查工程材料=785Mpa；为螺栓的许用拉应力安全系数,查机械设计手册表6.3取=1.5；d=mm=0.7mm 式（3.31）= Mpa =523.3 Mpa 式（3.32）35 箱体的设计1. 零件尺寸设计机械设计手册 ，机架设计中的铸铁箱体设计表288选用长400mm ，宽400mm，垂直高160mm，最小壁厚选20mm,具体结构及尺寸由零件图知。2. 设计计算危险截面确定底座是主要起支撑作用的底座，所以主要承受压力它所受的插削冲击力传递给它，所以它的危险截面在主轴于底座的接触面上止推轴承与底座的接触面可以近似看成一个长为一圈轴承周长，宽为轴承半径r的一个矩形进行大致的计算接触面的面积 sDr轴承的平均直径 D=(D+D2)/2=(38+43)/2=40.5mm rd/2 r2.5mmSDr 318mm2F/s10Mpa3. 选材由于底座主要承受压力的作用，铸铁相当与钢的受压能力也较好，铸铁和钢相比有较为便宜，铸铁又是箱体的首选材料，所以选用铸铁，选择结果牌号为HT150，抗压强度为150Mpa。4. 校核远远小与许用应力，所以满足条件4控制系统设计控制系统的设计包括单片机型号的选择,程序存储器的扩展,数据存储器的扩展,键盘及显示电路的设计,越界报警电路的设计,步进电动机驱动电路的设计,环形分配器的选择。此外,还包括电源电路的设计和程序设计。4.1单片机图4-1 AT89S51引脚图AT89S51的选择首先ADC0809作为模数转换器, ADC0809内部带有输出锁存器，它可以和AT89S51单片机直接相连。ADC0809的各项指标多与AT89S51匹配。其次目前市场比较常用AT89S51,是一个低功耗，高性能CMOS八位单片机，片内含4k Bytes ISP(In-system programmable)的可反复擦写1000次的Flash只读程序存储器，兼容标准MCS-51指令系统及80C51引脚结构，芯片内集成了通用8位中央处理器和ISP Flash存储单元，功能强大的微型计算机的AT89S51可为许多嵌入式控制应用系统提供高性价比的解决方案。综合与ADC0809的匹配、目前的单片机通用情况,最终我们选择了AT89S51。4.2驱动电路的设计本设计采用斩波恒流驱动，其波形图T1是一个高频开关管，T2是开关管的发射极接一只小电阻R，电动机绕组的电流经过这个电阻到地，所以这个电阻是电流取样电阻上的压降。比较器的一端接给定的电压Uc，另一段接取样电阻上的压降，当取样电压为0时，比较器输出高电平。当控制脉冲Ui为低电平时，T1和T2均截止；当Ui为高电平时，T1和T2两个开关均导通。电源向绕组供电。由于绕组电感的作用，R上的电感的作用，R上的电压逐渐升高，当超过给定电压Uc时比较器输出低电平，使与门也输出低电平，T1截止电源被切断；当取样电阻上的电压小于给定电压时，比较器输出高电平，与门也输出高电平，T1又导通，电源又开始想绕组供电，这样反复循环，直到Ui为低电平。如图4-2所示:图4-2 驱动电路的设计4.3电源电路设计步进电机和单片机的接线图如图4-3所示：图4-3 单片机与步进电机接线图电源电路设计如图4-4所示:图4-4 +24V电源电路设计4.4程序设计流程图如图4-5所示：等待键盘输入中断时间到响应中断，停止脉冲输出循环产生脉冲计算程序，算出步进电机的步数记录输入的数据键盘扫描图4-5 流程框图键盘子程序：KEY： LCALL KS2 检查有闭合键否？ JNZ MK1 A非0，有键闭合则转 LJMP MK7 无键闭合转返回MK1： LCALL DIR 有键闭合，则延时12ms LCALL DIR 消抖 LCALL KS2 再次检查有键闭合 JNZ MK2 若无键闭合则转 LJMP MK7 若无键闭合则转返回MK2： MOV P1，#F0H 发行线全扫描信号，列线全1 MOV A，P1 读入列状态 ANL A，#F0H 保留高4位 CJNE A，#FOH ，MK3 有键按下则转 LJMP MK7 无闭合键转返回MK3： MOV R2，A 保存列值 ORL A，#0FH 列线信号保留，行线全1 MOV P1，A 从列先输出 MOV A，P1 读入P1口状态 ANL A，#0FH 保留行线值 ADD A，R2 将行线值和列线值合并 MOV R2，A 暂存与R2中 MOV R3，#00H R3存简直 MOV DPTR，#TRBE 指向键值表首地址 MOV R4，#10H 查找次数送R4MK4： CLR A MOVC A，A+DPTR 表中值送入AMOV 70H,A 暂存与70H单元中MOV A,R2 键特征值送入ACJNE A,70H,MK6 未查到则转MK5: LCALL DIR 扫描1遍显示器LCALL KS2 还有键闭合否？JNZ MK5 若键未释放，则等待LCALL DIR 若键已释放，则延时12msLCALL DIR 消抖MOV A,R3 将键值存入A中RET 返主MK6: INC R3 键值加一INC DPTR 表地址加1DJNE R4,MK4 未查到，反复查找MK7: MOV A,#FFH 无闭合键标志存入A中RET 返主KS2: MOV P1,#FOH 闭合键判断子程序MOV A,P1 发全扫描信号，读入列线值ANL A,#FOH 保留列线值CPL A 取反，无键按下全0RET 返主TRBE: DB 01H,02H,03H,04H,05H,06H,07H,08HDB 09H,00H,FFH,FFH,FFH,FFH,FFH,FFH把输入的数字转换成字节数：MOV A,30HMOV B,#64HMUL ABMOV R6,AMOV R7,AMOV A,#31HMOV B,#OAHMUL ABADD A,R6MOV A,#32HMOV R6,A 这样高位在R7中，低位在R6中 计算程序： MOV R5,#00H MOV R4,#4BHDIV MOV A,R5 除数高8位送AJNZ BEGIN 除数非零则转BEGINMOV A,R4 除数底8位送AJZ OVER 除数为零置益出标志BEGIN: MOV A,R7 被除数高8位送A JNZ BEGIN1 被除数非零则转BEGIN1 MOV A,R6 被除数低8位送A JNZ BEGIN1 被除数非零则转BEGIN1 RET 被除数为零则返回BEGIN1: CLR A 清余数单元 MOV R2,A MOV R3,A MOV R1,#10H 双字节除法计数器置16DIV1: CLR C 开始R3R2R7R6左移 MOV A,R6 被除数低8位送A RLC A R6循环左移一位 MOV R6,A 左移结果送回 MOV A,R7 被除数高8位送A RLC A R7循环左移一位 MOV R7,A 左移结果回送 MOV A,R2 余数左移一位 RLC A MOV R2,A MOV A,R3 RLC A MOV R3,ADIV2: MOV A,R2 开始部分余数减除数 SUBB A,R3 低8位先减 MOV R0,A 暂存差值 MOV A,R3 MOV A,R5 高8位相减 JC NEXT 若部分余数除数则转NEXT INC R6 若部分余数除数则商为1 MOV R3,A 新余数存R3 R2 MOV A,R0 MOR R2,A NEXT: DJNZ R1,DIV1 16位除完则返回MOV A,R3 开始四舍五入处理JB A.7,ADD1 若余数最高位为1则进1CLR C 开始余数乘2处理MOV A,R2 RLC A 余数低8位乘2MOV R2,A MOV A,R3RLC A 余数8位乘2SUBB A,R5 余数*2除数JC NOOVER 若余数*小除数则转JNZ ADD1 若够减则转进1MOV A,R2 高8位相等时比较底8位SUBB A,R4 JC NOOVER 余数*2除数则转ADD1: MOV A,R6 开始商进1处理ADD A,#01HMOV R6,AMOV A,R7ADDC A,#00HMOV R7,ANOOVER: MOV OVER,#00H 清溢出标志RETOVER: MOV OVER,#00H 置溢出标志RET 中断、循环产生脉冲： ORG OO1BH T1中断入口 LJMP HERE 转到HERE处 ORG 2000H 主程序 MOV TMOD,#10H T1工作于方式1 MOV A,R3 设置计数初值 MOV TH1,A MOV A,R2 MOV TL1,A SETB EA CPU开中断 SETB ET1 允许T1中断 SETB TR1 启动T1定时INT: INC R0 正转加1 CJNE R0,#0AH,ZZ 如果计数器等于10修正 MOV R0,#00H ZZ: MOV A,R0 计数器值送A MOV DPTR,#ABC 指向数据存放首地址 MOVC A,A+DPTR 取控制字 MOV P1,A 送控制字到P1口 RETABC: DB OFCH,OF8H,OF9H,OF1H,0F3H DB OE3H,0E7H,0E6H,0EEH,0ECH等待键盘再次输入：中断就跳到在这里HERE CJNE A,#FFH KEY 将以上程序输入单片机，可实现步进电机转速的控制。结论在本次毕业设计中，我完成了回转工作台机械结构部分、电气控制部分的设计。机械部分我主要完成了一对圆柱直齿轮传动、蜗轮蜗杆传动的设计和箱体的设计，除了这些，我还对步进电机的选择、键与键槽的设计、轴承的选用等有所涉及，其中主要零部件的设计计算、校核最为复杂，占的篇幅也最多，如蜗轮蜗杆、齿轮。控制部分主要是采用单片机控制步进电机的转角，我选用的是AT89S51型单片机。在控制部分的设计中，我完成了步进电机与单片机的接线图、微机控制系统图、主程序流程图以及程序的编制。这次毕业设计，主要是用单片机作为控制系统来控制步进电机的转速，通过齿轮传动和蜗轮蜗杆传动，将动力传递到蜗轮上，蜗轮的转动再带动主轴转动，从而实现和主轴夹紧的工件的转动。所设计的回转工作台实用、简单、可靠、效率高。回顾本次毕业设计，基本上达到了设计要求，通过对大学所学知识的运用，从理论到实际迈出了可喜的一步。我相信有了这次毕业设计，我在今后的工作岗位中能得到更大的锻炼。由于所学知识有限，而且实践经验缺乏，因此，我的设计中难免存在缺陷和不足，恳请各位读者予以批评指正，以便在我今后的学习工作中得以弥补。参考文献1 同济大学、上海交通大学等院校编写组编.机械设计制图手册.上海：同济大学出版社，1990.2 齿轮手册编委会编.齿轮手册.北京：机械工业出版社，2001.3 邹丽新、翁桂荣主编.单片微型计算机原理及应用.苏州:苏州大学出版社，2001.4 张建民等编著.机电一体化系统设计.北京:高等教育出版社，1999.5 王晓明编著.电动机的单片机控制.北京:北京航空航天大学出版社，1997.6 王昆等主编.机械设计课程设计.北京:高等教育出版社，1996.7 邱宣怀主编.机械设计（第四版）.北京：高等教育出版社，1997.8 王永康、杨毅主编.机械制造技术课程设计指导书.长沙:湖南科学技术出版社,2001.9 周宏甫主编.机械制造技术基础.北京:高等教育出版社.2004.10 谢铁帮、李柱、席宏卓主编.互换性与测量技术基础.武汉:华中科技大学出版社，1998.11 任嘉卉主编.公差与配合手册.北京：机械工业出版社，2000-412 王新杰、李伟主编.数控加工技术基础.北京：轻工业出版社，1999.13 李福生等编.实用数控机床技术手册.北京：北京出版社，1993.14 郑堤主编.数控机床与编程.北京：机械工业出版社，2005-815 毛谦德、李振清主编.机械设计手册.北京：机械工业出版社，1994-916 上海柴油机厂工艺设备研究所编.金属切削机床设计手册.北京：机械工业出版社，1984.17 范思冲主编，丛肇助、周建平副主编.画法几何及机械制图.北京：机械工业出版社，1996.18 Dan G.Sporea and Gabriel Dumitru.Analytical and computational models for a laser radiation field scattered by rough surface.Opt.Eng.June 1996,35(6):1632-1646.19 Brodman R,et al.An Optical Instrument for Measuring the Surface Roughness in Production Control.Annals of the CIRP.1984,33(1):403-406.附录附录1英文原文：Mechanical Design and Manufacturing Processes Mechanical design is the application of science and technology to devise new or improved products for the purpose of satisfying human needs. It is a vast field of engineering technology which not only concerns itself with the original conception of the product in terms of its size, shape and construction details, but also considers the various factors involved in the manufacture, marketing and use of the product. People who perform the various functions of mechanical design are typically called designers, or design engineers. Mechanical design is basically a creative activity. However, in addition to being innovative, a design engineer must also have a solid background in the areas of mechanical drawing, kinematics, dynamics, materials engineering, strength ofmaterials and manufacturing processes. As stated previously, the purpose of mechanical design is to produce a product which will serve a need for man. Inventions, discoveries and scientific knowledge by themselves do not necessarily benefit people; only if they are incorporated into a designed product will a benefit be derived. It should be recognized, therefore, that a human need must be identified before a particular product is designed. Mechanical design should be considered to be an opportunity to use innovative talents to envision a design of a product, to analyze the system and then make sound judgments on how the product is to be manufactured. It is important to understand the fundamentals of engineering rather than memorize mere facts and equations. There are no facts or equations which alone can be used to provide all the correct decisions required to produce a good design.On the other hand, any calculations made must be done with the utmost care and precision. For example, if a decimal point is misplaced, an otherwise acceptable design may not function.Good designs require trying new ideas and being willing to take a certain amount of risk, knowing that if the new idea does not work the existing method can be reinstated. Thus a designer must have patience, since there is no assurance of success for the time and effort expended. Creating a completely new design generally requires that many old and well-established methods be thrust aside. This is not easy since many people cling to familiar ideas, techniques and attitudes. A design engineer should constantly search for ways to improve an existing product and must decide what old, proven concepts should be used and what new, untried ideas should be incorporated. New designs generally have bugs or unforeseen problems which must be worked out before the superior characteristics of the new designs can be enjoyed. Thus there is a chance for a superior product, but only at higher risk.It should be emphasized that,if a design does not warrant radical new methods, such methods should not be applied merely for the sake of change. During the beginning stages of design, creativity should be allowed to flourish without a great number of constraints.Even though many impractical ideas may arise, it is usually easy to eliminate them in the early stages of design before firm details are required by manufac- turing. In this way, innovative ideas are not inhibited. Quite often, more than one design is developed, up to the point where they can be compared against each other.It is entirely possible that the design which is ultimately accepted will use ideas existing in one of the rejected designs that did not show as much overall promise. Psychologists frequently talk about trying to fit people to the machines they operate. It is essentially the responsibility of the design engineer to strive to fit machines to people. This is not an easy task, since there is really no average person for which certain operating dimensions and procedures are optimum. Another important point which should be recognized is that a design engineer must be able to communicate ideas to other people if they are to be incorporated. Communicating the design to others is the final, vital step in the design process. Undoubtedly many great designs, inventions, and creative works have been lost to mankind simply because the originators were unable or unwilling to explain their accomplishments to others. Presentation is a selling job. The engineer, when presenting a new solution to administrative, management, or supervisory persons, is attempting to sell or to prove to them that this solution is a better one. Unless this can be done successfully, the time and effort spent on obtaining the solution have been largely wasted. Basically, there are only three means of communication available to us. These are the written, the oral, and the graphical forms. Therefore the successful engineer will be technically competent and versatile in all three forms of communication. A technically competent person who lacks ability in any one of these forms is severely handicapped.If ability in all three forms is lacking, no one will ever know how competent that person is! The competent engineer should not be afraid of the possibility of not succeeding in a presentation. In fact, occasional failure should be expected because failure or criticism seems to accompany every really creative idea. There is a great deal to be learned from a failure,and the greatest gains are obtained by those willing to risk defeat. In the final analysis, the real failure would lie in deciding not to make the presentation at all. To communicate effectively, the following questions must be answered: (1) Does the design really serve a human need? (2) Will it be competitive with existing products of rival companies? (3) Is it economical to produce? (4) Can it be readily maintained? (5) Will it sell and make a profit? Only time will provide the true answers to the preceding questions, but the product should be designed, manufactured and marketed only with initial affirmative answers. The design engineer also must communicate the finalized design to manufacturing through the use of detail and assembly drawings. Quite often, a problem will occur during the manufacturing cycle3. It may be that a change is required in the dimensioning or tolerancing of a part so that it can be more readily produced. This fails in the category of engineering changes which must be approved by the design engineer so that the product function will not be adversely affected. In other cases, a deficiency in the design may appear during assembly or testing just prior to shipping. These realities simply bear out the fact that design is a living process. There is always a better way to do it and the designer should constantly strive towards finding that better way. Designing starts with a need,real or imagined.Existing apparatus may need improvements in durability, efficiently, weight, speed, or cost. New apparatus may be needed to perform a function previously done by men, such as computation, assembly, or servicing. With the objective wholly or partly defined, the next step in design is the conception of mechanisms and their arrangements that will perform the needed functions.For this, freehand sketching is of great value, not only as a record of ones thoughts and as an aid in discussion with others, but particularly for communication with ones own mind, as a stimulant for creative ideas. When the general shape and a few dimensions of the several components become apparent, analysis can begin in earnest.The analysis will have as its objective satisfactory or superior performance, plus safety and durability with minimum weight,and a competitive east. Optimum proportions and dimensions will be sought for each critically loaded section,together with a balance between the strength of the several components. Materials and their treatment will be chosen. These important objectives can be attained only by analysis based upon the principles of mechanics, such as those of statics for reaction forces and for the optimum utilization of friction; of dynamics for inertia, acceleration, and energy;of elasticity and strength of materials for stress and deflection; and of fluid mechanics for lubrication and hydrodynamic drives. Finally, a design based upon function and reliability will be completed, and a prototype may be built. If its tests are satisfactory, and if the device is to be produced in quantity, the initial design will undergo certain modifications that enable it to be manufactured in quantity at a lower cost. During subsequent years of manufacture and service, the design is likely to undergo changes as new ideas are conceived or as further analysis based upon tests and experience indicate alterations. Sales appeal, customer satisfaction, and manufacture cost are all related to design, and ability in design is intimately involved in the success of an engineering venture. To stimulate creative thought, the following rules are suggested for the designer. 1. Apply ingenuity to utilize desired physical properties and to control undesired ones. The performance requirements of a machine are met by utilizing laws of nature or properties of matter (e. g., flexibility, strength, gravity,inertia,buoyancy,centrifugal for, principles of the lever and inclined plane, friction, viscosity, fluid pressure, and thermal expansion), also the many electrical, optical, thermal, and chemical phenomena. However, what may be useful in one application may be detrimental in the next. Flexibility is desired in valve springs but not in the valve camshaft; friction is desired at the clutch face but not in the clutch bearing. Ingenuity in design should be applied to utilize and control thephysical properties that are desired and to minimize those that are not desired. 2. Provide for favorable stress distribute and stiffness with minimum weight. On components subjected to fluctuating stress, particular attention is given to a reduction in stress concentration, and to an increase of strength at fillets, threads, holes, and fits. Stress reduction are made by modification in shape, and strengthening may be done by prestressing treatments such as surface rolling and shallow hardening. Hollow shafts and tubing, and box sections give a favorable stress distribution, together with stiffness and minimum weight. Sufficient stiffness to maintain alignment and uniform pressure between contacting surfaces should be provided for crank, cam, and gear shafts, and for enclosures and frames containing bearing supports. The stiffness of shafts and other components must be suitable to avoid resonant vibrations. 3. Use &zsic equations to calculate and optimize dimensions.The fundamental equations of mechanics and the other sciences are the accepted bases for calculations. They are sometimes rearranged in special forms to facilitate the determination or optimization of dimensions, such as thebeam and surface stress equations for determining gear-tooth size. Factors may be added to a fundamental equation for conditions not analytically determinable, e. g. , on thin steel tubes, an allowance for corrosion added to the thickness based on pressure. When it is necessary to apply a fundamental equation to shapes, materials, or conditions which only approximate the assumptions for its derivation, it is done in a manner which gives results on the safe side.In situations where data are incomplete, equations of the sciences may be used as proportioning guides to extend a satisfactory design to new capacities. 4.Choose materials for a combination of properties.Materials should be chosen for a combination of pertinent properties, not only for strengths, hardness, and weight, but sometimes for resistance to impact, corrosion, and low or high temperatures. Cost and fabrication properties are factors, such as weldability, machinability, sensitivity to variation in heat-treating temperatures, and required coating. 5. Select carefully between stock and integral components. A previously developed components is frequently selected by a designer and his company from the stocks of parts manufacturers, if the component meet the performance and reliability requirements and is adaptable without additional development costs to the particular machine being designed.However, its selection should be carefully made with a full knowledge of its propcrties, since the reputation and liability of the company suffer if there is a failure in any one of the machines parts. In other eases the strength, reliability, and cost requirements are better met if the designer of the machine also designs the component, with the particular advantage of compactness if it is designs integral with other components, e. g., gears to be forged in clusters or integral with a shaft. 6. Provide for accurate location and non interference of parts in assembly. A good design provides for the correct locating of parts and for easy assembly and repair. Shoulders and pilot surfaces give accurate location without measurement during assembly. Shapes can be designed so that parts cannot be assembled backwards or in the wrong place. Interferences, as between screws in tapped holes, and between linkages must he foreseen and prevended.Inaccurate alignment and positioning between such assemblies must be avoided, or provision must be made to minimize any resulting detrimental displacements and stresses.The human race has distinguished itself from all other forms of life by using tools and intelligence to create items that serve to make life easier and more enjoyable. Through the centuries, both the tools and the energy sources to power these tools have evolved to meet the increasing sophistication and complexity of mankinds ideas. In their earliest forms, tools primarily consisted of stone instruments. Considering tile relative simplicity of the items being made and the materials being shaped, stone was adequate. When iron tools were invented, durable metals and more sophisticated articles could be produced. The twentieth century has seen the creation of products made from themost durable and, consequently, the most unmachinable materials in history. In an effort to meet the manufacturing challenges created by these materials, tools have now evolved to include materials such as alloy steel, carbide, diamond, and ceramics. A similar evolution has taken place with the methods used to power our tools. Initially,tools were powered by muscles; either human or animal. However as the powers of water, wind, steam, and electricity were harnessed, mankind was able to further extended manufacturing capabilities with new machines, greater accuracy, and faster machining rates. Every time new tools, tool materials, and power sources are utilized, the efficiency and capabilities of manufacturers are greatly enhanced. However as old problems are solved, new problems and challenges arise so that the manufacturers of today are faced with tough questions such as the following: How do you drill a 2 mm diameter hole 670 mm deep without experiencing taper or runout? Is there a way to efficiently deburr passageways inside complex castings and guarantee 100 % that no burrs were missed? Is there a welding process that can eliminate the thermal damage now occurring to my product? Since the 1940s, a revolution in manufacturing has been taking place that once again allows manufacturers to meet the demands imposed by increasingly sophisticated designs and durable, but in many cases nearly unmachinable, materials. This manufacturing revolution is now, as it has been in the past, centered on the use of new tools and new forms of energy.The result has been the introduction of new manufacturing processes used for material removal, forming, and joining, known today as nontraditional manufacturing processes. The conventional manufacturing processes in use today for material removal primarily rely on electric motors and hard tool materials to perform tasks such as sawing, drilling, an broaching. Conventional forming operations are performed with the energy from electric motors, hydraulics, and gravity. Likewise, material joining is conventionally accomplished with thermal energy sources such as burning gases and electric arcs. In contrast, nontraditional manufacturing processes harness energy sources considered unconventional by yesterdays standards. Material removal can now be accomplished with electrochemical reactions, high-temperature plasmas, and high-velocity jets of liquids and abrasives. Materials that in the past have been extremely difficult to form, are nowformed with magnetic fields, explosives, and the shock waves from powerful electric sparks. Material-joining capabilities have been expanded with the use of high-frequency sound waves and beams of electrons. In the past 50 years, over 20 different nontraditional manufacturing processes have been invented and successfully implemented into production. The reason there are such a large number of nontraditional processes is the same reason there are such a large number of conventional processes; each process has its own characteristic attributes and limitations, hence no one process is best for all manufacturing situations. For example, nontraditional process are sometimes applied to increase productivity either by reducing the number of overall manufacturing operations required to produce a product or by performing operations faster than the previously used method. In other cases, nontraditional processes are used to reduce the number of rejects experienced by the old manufacturing method by increasing repeatability, reducing in-process breakage of fragile workpieces, or by minimizing detrimental effects on workpiece properties. Because of the aforementioned attributes, nontraditional manufacturing processes have experienced steady growth since their introduction. An increasing growth rate for these processes in the future is assured for the following reasons: 1.Currently, nontraditional processes possess virtually unlimited capabilities when compared with conventional processes, except for volumetric material removal rates. Great advances have been made in the past few years in increasing the removal rates of some of these processes, and there is no reason to believe that this trend will not continue into the future. 2. Approximately one half of the nontraditional manufacturing processes are available with computer control of the process parameters. The use of computers lends simplicity to processes that people may be unfamiliar with, and thereby accelerates acceptance. Additionally, computer control assures reliability and repeatabilitys, which also accelerates acceptance and implementation.3.Most nontraditional processes are capable of being adaptively-controlled through the use of vision systems, laser gages, and other in-process inspection techniques. If, for example, the in-process inspection system determines that the size of holes being produced in a product are becoming smaller, the size can be modified without changing hard tools, such as drills.4.The implementation of nontraditional manufacturing processes will continus to increase as manufacturing engineers, product designers, and metallurgical engineers become increasingly aware of the unique capabilties and benefits that nontraditional manufacturing processes provide.附录2中文译文：机械设计及加工工艺机械设计是一门通过设计新产品或者改进老产品，满足人类需求的应用学科。它涉及工程技术的很多领域，主要研究产品的尺寸、形状和详细结构的基本构思，还要研究产品在制造、销售和使用等方面的问题。进行各种机械设计工作的人员通常被称为设计人员或者设计工程师。机械设计是一项创造性的工作。设计工程师不仅在工作上要有创新性，还必须在机械制图、运动学、动力学、工程材料、材料力学和机械制造工艺等方面具有深厚的基础知识。如前面所述，机械设计的目的是生产满足人类需求的产品。发明、发现和科学知识本身并不一定能给人类带来益处，只有当它们被用在产品上才能产生效益。因而，应该认识到在一个特定产品进行设计之前，必须先确定人们是否需要这种产品。应当把机械设计看成设计人员运用创造性的才能进行产品设计、系统分析和制订产品的制造工艺的一个良机。掌握工程基础知识要比熟记一些数据和公式更为重要。仅仅使用数据和公式是不足以在一个好的设计中做出所需的全部决定的。另一方面，应该认真精确地进行所有运算。例如，即使将一个小数点的位置放错，也会使正确的设计变成错误的。一个好的设计人员应该勇于提出新的想法，而且愿意承担一定的风险，当新的方法不适用时，就恢复采用原来的方法。因此，设计人员必须要有耐心，因为所花费的时间和努力并不能保证带来成功。一个全新的设计，要求摒弃许多陈旧的、为人们所熟知的方法。由于许多人易于墨守成规，这样做并不是一件容易的事情。一位设计工程师应该不断地探索改进现有产品的办法，在此过程中应该认真选择原有的、经过验证的设计原理，将其与未经过验证的新观念结合起来。新设计本身会有许多缺陷和未能预料的问题发生，只有当这些缺陷和问题被解决之后，才能体现出新产品的优越性。因此，一个性能优越的产品诞生的同时，也伴随着较高的风险。应该强调的是，如果设计本身不要求采用全新的方法，就没有必要仅仅为了变革的目的而采用新办法。在设计的初始阶段，应该允许设计人员充分发挥创造性，不受各种约束。即使产生了许多不切合实际的想法，也会在设计的早期，即绘制生产图纸之前被改正。只有这样，才不至于堵塞创新的思路。通常要提出几套设计方案，然后加以比较。很有可能在最后选定的方案中，采用了某些未被接受的方案中的一些想法。心理学家经常谈论如何使人们适应他们所操作的机器。设计人员的基本职责是努力使机器来适应人们。这并不是一项容易的工作，因为实际上并不存在着一个对所有人来说都是最优的操作范围和操作过程。另一个应该被认识到的重要问题是，设计工程师必须能够同其他有关人员进行交流和沟通。与其他人就设计方案进行交流和沟通是设计过程的最后和关键阶段。毫无疑问，有许多伟大的设计、发明
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