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C616车床的横向伺服进给单元改造【5张CAD图纸和说明书】

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C616车床的横向伺服进给单元改造【5张CAD图纸和说明书】.rar

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A3-轴.dwg

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关键词：: 5张CAD图纸和说明书 c616 车床横向伺服进给单元改造 cad 图纸以及说明书仿单

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摘　　要

本次设计主要是针对C616车床的横向进给伺服系统改造，机械方面的改造过程是：拆掉原手动刀架和小拖板，安装上数控刀架；拆掉普通丝杆、光杆进给箱和溜板箱，换上滚珠丝杠螺母副；保留原手动机构，用于调整操作，原有的支撑结构也保留，采用一级齿轮减速，步进电机、齿轮箱体安装在中拖板的后侧。

机械部分采用步进电动机驱动滚珠丝杠，然后再通过滚珠螺母副来动工作台运作。电器部分采用MCS—8051单片机来对步进电动机进行适时有效的控制，同时为了便于人机对话，通过输入程序来更好的解决形状复杂、精密、难加工的问题。这次设计可以准确地实现规定的动作、自动化程度较高、能灵活迅速的适应加工零件的更变。

关键字：车床步进电动机单片机人机对话精密

abstract

The system is mainly aimed C616 lathe infeed servo system transformation, the transformation process is mechanical: the original manual turret removed and a small carriage, the installation of CNC turret; removed ordinary screw, rod feed box and slide crate, put the ball screw nut; retain the original manual body for adjusting operation, the support structure to retain the original, with a gear, stepper motor, gear box installed in the extension unit back.

Stepping motor drive mechanical ball screw, and then through the ball nut to move the operation table. Electrical part to the use of MCS-8051 single-chip stepper motor for timely and effective control, and in order to facilitate the man-machine dialogue, by entering the program to better solve the shape of the complex, sophisticated and difficult to process problems. The design can be accurately specified action to achieve high degree of automation, flexibility to quickly adapt to change more parts processing.

Keywords: Lathe; Stepper motor; SCM; Man-machine dialogue; Precision

目　　录

摘要 II

Abstract III

绪论 2

1 机械部分改造的设计及计算 3

1.1 课题的来源与意义及总体方案的确定 3

1.1.1 课题的来源与意义： 3

1.1.2 总体方案的确定： 4

1.2 滚珠丝杠副的计算和选型 5

1.2.1 确定系统的脉冲当量 5

1.2.2 切削力计算 6

1.2.3 传动效率 8

1.3 步进电动机的选择 10

1.3.1 传动比的计算 10

1.3.2 转动惯量的计算 11

1.4 齿轮设计及强度校核计算 15

1.4.1 选定齿轮类型，精度等级，材料及齿数 15

1.4.2 按照齿面接触疲劳强度校核 16

1.4.3 校核齿根弯曲疲劳强度 18

1.5 轴的设计（中间轴）及校核 19

1.5.1 选择轴的材料 19

1.5.2 初步估算轴的最小直径 19

1.5.3 轴的结构设计 20

1.5.4 按弯扭合成应力校核轴的强度 20

1.5.5 精确校核轴的疲劳强度 23

1.6 滚动轴承的选择和计算 28

1.7 键联接的选择和强度校核（即中间轴） 29

1.7.1 大齿轮2与轴的键联接 29

1.7.2小齿轮3和轴的键联接 30

2 机床横向伺服进给单元电气控制部分设计 31

2.1 电气控制系统方案的确定 31

2.1.1 步进电动机与丝杠的联接 32

2.1.2 8051单片机的选择 32

2.2 步进电动机开环控制系统设计 32

2.2.1 脉冲分配器 33

2.2.2 光隔离电路 36

2.2.3 步进电动机驱动电路 37

2.3 8255可编程控制芯片的扩展 39

2.4 辅助电路的设计 40

2.4.1 8051单片机的时钟电路 40

2.4.2 复位电路 41

2.4.3 越界报警电路 41

2.5 操作面板设计的简要介绍 42

2.6 绘制机床电气控制电路原理图 42

结论 44

致谢 45

参考文献 46

绪论

随着我国生产技术进步，在机械制造业中，数控机床越来越受到企业的欢迎。企业一方面投入大量资金购买数控车床，另一方面更新改造现有普通机床，通过为普通机床添加数控装置，将普通机床改造成数控机床，这是许多中小型企业面临的重要技改措施。

数控机床能够适应市场对产品多样化、高精度的要求。因此得到了越来越广泛的应用。但是，商品化的数控机床价格高，一致于推广应用受到限制，而我国又现存有大量的普通机床，利用较先进的数控系统，对现有普通机床进行技术改造，对提高我国机械行业的数控加工技术具有更重要意义。数控机床是衡量一个国家机械制造业水平的重要指标。根据我国机床拥有量大，生产规模小的具体国情，将普通机床通过数控化改造为经济型数控机床是我国机械工业技术改造的这样目标。但从我国目前机械工业制造水平与发达国家相比差距较大，而且从目前企业所面临的情况看，因数控机床价格较贵，一次性投资较大，使企业心有余而力不足。

因此，我国作为机床大国。对普通机床数控化改造作为一种良好的有效途径。这样机床改造花费少，改造设计针对性强、时间短，改造设计后的机床大多能够克服机床的缺点和存在的问题，生产效率高。

1 机械部分改造的设计及计算

1.1 课题的来源与意义及总体方案的确定

1.1.1 课题的来源与意义：

社会发展的今天，现代工业发展非常迅速突出，普通机床已越来越不能满足现代加工工艺及提高劳动生产率的要求。如果设备全部更新换代不仅资金投入大，成本太高，而且原有设备的闲置又将造成极大浪费。所以最简易经济的办法就是进行数控化改造。数控机床作为机电一体化的典型产品，在机械制造业中发挥着巨大的作用，很好的解决了现代机械制造中结构复杂、精密、批量小、多变零件的加工问题，且能稳定产品的加工质量，大幅度地提高生产效率。但从我国目前机械工业制造水平与发达国家相比差距较大，而且从目前企业所面临的情况看，因数控机床价格较贵，一次性投资较大，使企业心有余而力不足。因此，我国作为机床大国。对普通机床数控化改造作为一种良好的有效途径。这样机床改造花费少，改造设计针对性强、时间短，改造设计后的机床大多能够克服机床的缺点和存在的问题，生产效率高。

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A0-电气原理图.gif

A0-横向进给装配图.gif

A2-丝杠.gif

A3-齿轮.gif

A3-轴.gif

内容简介：: 毕业设计（论文）意见指导教师意见：教师签字：年月日评阅人意见：评阅人签字：年月日答辩委员会意见：成绩评定：答辩组组长意见：年月日 24毕业生毕业设计答辩记录姓名专业班级答辩时间答辩地点设计题目基于C616车床的横向伺服进给单元改造1.什么是脉冲当量？答：脉冲当量是指一个进给脉冲使车床执行部件产生的进给量,它是衡量数控机床加工精度的一个基本技术参数.2.脉冲当量是由什么来确定的？答：脉冲当量应根据机床精度来确定.3.改造后的机床有什么好处？答：机床改造花费少，改造设计针对性强、时间短，改造设计后的机床大多能够克服机床的缺点和存在的问题，生产效率高。4. 进给伺服系统机械部分的计算与选型的内容包括？答：进给伺服系统机械部分的计算与选型的内容包括:运动参数、动力参数的计算、传动比的分配、转动惯量、等效转矩等计算.5. 选择步进电动机时应该注意什么？答：选择步进电动机时,必须根据机械传动装置及负载折算到电动机轴上的等效转动惯量,分别计算各种情况下所需要的力矩,再根据步进电动机最大静转矩和启动运行频率特性选择合适的步进电动机,负载惯量是驱动系统的主要参数之一,它对选择步进电动机,设计传动比等都有十分重要的意义,如果该惯量与电动机的匹配不当,系统就得不到快速反应,甚至失效.记录教师（签名）：附录1车削、铣削和磨削用于车外圆，端面和镗孔等加工的机床称作机床。车削很少在其他种类的机床上进行，因为其他的车床都不能向车床那样方便得进行车削加工。由于车创出了用于车外圆外还能用于镗孔，车断面，钻孔和铰孔，车床的多功能型可以使工件在一次定位安装中完成多种加工。这就是在生产中普遍使用各种车床比其他种类的车床都要多的原因。两千多年前就已经有了车床。现代车床可以追述到大约1797年，那时候亨利*莫德斯利发明了一种具有丝杠的车床。这种车床可以控制工具的机械进给。这位聪明的英国人还发明了一种把主轴和丝杠相连接的变速装置，这样就可以切削螺纹。车床的主要部件：床身，主轴箱组件，尾架组件，托板组件，变速齿轮箱，丝杠和光杠。床身是车床的基础件。它通常是由经过充分正火或时效处理的灰铸铁或者球墨铸铁制成，它是一个坚固的刚性框架，所有其他主要部件都安装在床身上。通常在床身上面有内外两组相平行的导轨。一些制造厂生产的四个条导轨都采用倒v 形，而另一些制造厂则将倒 V 形导轨和平面导轨相结合。由于其他的部件要安装在导轨上并（或）在导轨上移动，导轨要经过精密的加工，以保证其装配精度。同样的，在操作中应当小心，以避免损伤导轨。导轨上的任何误差，常常会使整个机床的精度遭到破坏。大多数现代车床的导轨要进行表面淬火处理，以减少摩擦和擦伤，具有更大的耐磨性。主轴箱安装在床身一端内导轨的固定位置上。它提供动力，使工件在各种速度下旋转。它基本上由一个安装在精密轴承中的空心主轴和一系列变速齿轮类似于卡车变速箱所组成，通过变速齿轮，主轴可以在许多种转速下旋转。大多数车床有818种转速，一般按等比级数排列。在现代车床上只需要搬动24个手柄，就能得到全部挡位的转速。目前发展的趋势是通过电气的或者机械的装置进行无极变速。由于车床的精度在很大程度上取决于主轴，因此主轴的结构尺寸较大，通常安装在紧密配合的重型圆锥滚子轴承或球轴承中。主轴中有一个贯穿全长的通孔，长棒料可以通过该孔送料。主轴孔的大小是车床的一个重要尺寸，因为当工件必须通过主轴孔供料时，它确定了能够加工棒料毛胚的最大外径尺寸。主轴的内端面从主轴箱中凸出，其上可以安装多种卡盘，花盘，档块。而小型的车床常带有螺纹截面供安装卡盘之用。大多数车床使用偏心夹或键动圆锥轴头。这些附件组成了一个大直径的圆锥体，以保证对卡盘进行精确的装配，并且不用旋转这些笨重的附件就可以锁定或者松开卡盘或者花盘。主轴由电动机经V带或者无声链装置提供动力。大多数现代车床都装有515 马力的电动机，为硬质合金和金属陶瓷合金刀具提供了足够的动力，进行高速切削。尾座组件主要由三部分组成。底座与床身的内侧导轨相配合，并可以在导轨上作纵向移动，底座上有一个可以使整个尾座组件夹紧在任意位置上的装置。尾座安装在底座上，可以沿键槽在底座上横向移动，使尾座与主轴箱中的主轴对中并为切削圆锥体提供方便。尾座组件的第三部分是尾座套筒，它是一个直径通常在23英寸之间的刚制空心圆柱轴。通过手轮和螺杆，尾座套筒可以在尾座体中纵向移入和移出几英寸。活动套筒的开口一端具有莫式锥度，可以用于安装顶尖或者诸如钻头之类的各种工具。通常在活动套筒的外表面刻有几英寸的刻度，以控制尾座的前后移动。锁定装置可以使套筒在所需要的位置上夹紧。托板组件用于安装和移动切削工具。托板是一个相对平滑的H形状的铸件，安装在床身外侧导轨上，并可以在上面移动。大托板上有横向导轨，使横向托板可以安装在上面，并通过丝杠使其运动，丝杠由一个小手柄和刻度盘控制。横托板可以带动刀具垂直于工件的旋转轴线切割。大多数车床的安装架安装在复式刀座上，刀座上有底座，底座安装在横托板上，可绕垂直轴和上刀架转动，上刀架安装在底座上，可用手轮和刻度盘控制一个段丝杠使其前后移动。溜板箱在大托板前面，通过溜板箱内的机械装置可以手动和动力驱动大托板以及动力驱动横托板。通过转动溜板箱前的小轮，可以手动操作托板沿床身移动。手轮的另一端与溜板箱背面的小齿轮连接，小齿轮与齿条啮合，齿轮倒装在床身前上边缘的下面。利用光杠可以将动力传递给大托板和横托板。光杠上有一个几乎可以贯穿整个光杠的键槽，光杠通过两个转向相反并用键连接的锥齿齿轮传递动力。通过溜板箱前的换向手柄可使啮合齿轮与其中的一个锥齿轮啮合，为大托板提供“向前”或者“向后” 动力。适当的离合器或者与齿条小齿轮连接或者与横托板的螺杆连接，使托板纵向移动或者使其横托板横向移动。对于螺纹加工，丝杠提供了第二种纵向移动的方法。光杠通过摩擦力离合器驱动托板移动，离合器可能会产生打滑现象。而丝杠产生的运动是通过溜板箱与丝杠之间的直接机械连接来实现的，对开螺母可以实现这种连接。通过溜板箱前面的夹紧手柄可以使对开螺母紧紧包合丝杠。对开螺母闭合时，可以沿丝杠直接驱动托板，而不会出现打滑的可能性。现代的车床由一个变速齿轮箱，齿轮箱的输入端由车床主轴通过合适的齿轮传动来驱动。齿轮箱的输出端与丝杠连接。主轴就是这样通过齿轮传动链驱动变速齿轮箱，再带动丝杠和光杠，然后带动托板，刀具就可以按照株洲的转速纵向地或者横向的精确移动。一台典型的车床主轴每旋转一圈，通过光杠可以获得从0.002到0.118英寸范围内的48种进给量，而使用丝杠可以车削从1.5到92牙/英寸的48种不同的螺纹。一些老式的或者廉价的车床为了能够得到所有的进给量和加工出所有的螺纹，必须更换主轴和变速齿轮箱之间的齿轮系中的一个或者两个齿轮。铣削是机械加工的一个基本方法。在这一加工过程中，当工件沿垂直旋转刀具轴线方向进给时，在工件上形成并除去切屑从而逐渐的铣出表面。有时候，工件是固定的，而刀具处于进给状态。大多数情况之下，使用多齿刀具，金属切削量大，只需一次铣削就可以获得所期望的表现。在铣削加工中使用的刀具称作铣刀。它通常是一个绕其轴线旋转并且周边带有同间距齿的圆柱体，铣刀齿间歇性接触并铣削工件。在某些情况下，铣刀上的刀齿会高出圆柱体的一端或两端。由于铣削切削金属速度快，并且能产生良好的表面光洁度，故特别适合大规模生产加工。为了实现这一目的，已经制造出了质量一流的铣床。然而在机修车间和工具模具加工中心也已经广泛的使用了非常精确的多功能通用的铣床。车间里拥有一台铣床和一台普通车床就能加工出具有适合尺寸的各种产品。铣削操作类型铣削操作可以分为两大类，每一类又有多种类型。1圆周铣削在圆周铣削中，使用的铣刀刀齿固定在刀体的圆周上，工件铣削表面与旋转刀具轴线平行，从而加工表面。使用这种方法可以加工出平面和成型表面，加工中表面横截面与刀具的轴向外轮廓相一致。这种加工过程常被称为平面铣削。2端面铣削铣削平面与刀具的轴线垂直，被加工平面是刀具位于周边和端面的齿综合作用形成的。刀具周边齿完成铣削的主要任务，而端面齿用于精铣。圆周铣削和端面铣削的基本概念，圆周铣削通常使用卧式铣床，端面铣削则既可以在卧式铣床又可以在立式铣床上进行。铣削面的形成：铣削时可以采用两种完全不同的方法。应注意，在铣削时，铣刀旋转方向与工件进给方向相反，而在顺铣时候铣刀旋转与工件进给方向相同。在逆铣削过程中，当铣刀齿刚刚切入工件时候，切削时非常薄的，然后渐渐增厚，在刀齿离开工件的地方，切屑最厚。在两种铣削方法中，切屑的形成是不同的，逆铣削过程中，道具推动工件并使工件从工作台上提升的趋势，这种作用有助于消除铣床工作台进给螺旋杆和螺母的间隙，从而形成平稳的切削。然而，这种作用也有造成共建与夹紧装置之间的松动的趋势，这是应当施加更大夹紧力。此外，铣削平面的平整度主要取决于切削刃的锋利程度。顺铣时，最大切屑厚度产于靠近刀具与工件的接触点处。由于相对运动趋于把工件拉向铣刀，如果采用顺铣法，要消除工作台进给螺杆可能产生的松动。因为，对于不能于用于顺铣的铣床，不要采用顺铣的方法。因为在铣刀结束切削时，处于切线方向的被切材料发生屈服，所以与逆铣削相比，顺铣的被加工表面没有之类的切很。顺铣的另一个优势是切削力趋于将工件压紧在工作台上，因此对工件的夹紧力可以小于逆铣。这一优势可以用于铣削较薄的工件时或进行强力切削。顺铣的弱点是铣刀刚刚一切削每片铁屑时，刀齿会撞击工件的表面。如果工件表面坚硬，向铸铁，就会使刀齿迅速变钝。铣刀铣刀的分类有多种的方法，一种方法是根据刀具后角将铣刀分为两大类：1.仿型铣刀每个刀齿在切削力的背面磨了一个很小的棱面形成后角，切削刃可以是直线的也可以是曲线的。2.成型或凸轮型后角铣刀每个齿的横截面在切削刃的背面成偏心曲线状，以产生后角。偏心后角的各面与切削刃平行，具有切削刃的相同形状。这种类型的铣刀仅需要磨削齿的前刀面就可以变得锋利，只要切削刃的外形保持不变。铣刀的另一种分类方法是根据铣刀安装的方法进行分类。心轴铣刀带有一个中心孔以使铣刀安装在心轴上。带柄铣刀有一锥柄或直柄轴，含锥形柄的铣刀可以直接安装在铣床的心轴上，而直柄轴的铣刀则是夹持在卡盘里。平面铣刀通过常用螺栓固定在刀轴的末端上。根据这种分类的方法，通用型的铣刀可分类如下：心轴铣刀：圆柱形铣刀，角度铣刀，侧刃铣刀，嵌齿铣刀，错齿铣刀，成型铣刀，开槽铣刀，高速切削刀。带柄铣刀：端面铣刀， T形槽铣刀，整体式铣刀，半圆键座铣刀套式铣刀，高速切削刀，空心铣刀。铣刀的类型圆柱形铣刀是在圆周上有直的或者螺旋形的齿的圆柱形或者盘形铣刀。他们可以用来铣削平面，这种铣削称作平面铣削。螺旋形的铣刀上的每个齿是逐渐地接触工件，在给定的时间内，一般有多齿进行铣削，这样可以减少震动，获得一个比较平滑的表面。因此，与直齿铣刀相比，这种类型的铣刀，通常使用的更多。侧刃铣刀的齿除了在圆柱刀体的一端或者两端向径向延伸之外，与圆柱形铣刀是相似的。侧刃铣刀的刀齿既可以是直线运动，也可以是螺旋形的，这种铣刀一般较狭小，具有盘形的形状。在跨式铣削加工中常常讲两个或更多的侧刃铣刀同时相间的安装在一个刀杆上同步进行切削。双联槽铣刀是由两个侧刃铣刀组成，但是在铣槽时，作为一组铣刀进行操作。在两个铣刀之间增加了一些薄垫片，以调整之间的间距。错齿铣刀是较薄的圆柱形铣刀，刀上有互相交错得刀齿，乡邻刀齿具有相反的螺旋角。这种铣削经研磨后仅用于周铣，在每个齿突出的一边，留有供切屑排除的缝隙。这种类型的铣刀可用于高速切削，在铣削深槽时可以发挥独特的作用。开槽铣刀是一种薄型的圆柱形铣刀，厚度一般为1/323/16英寸。这种铣刀的侧面呈盘状，有间隙，可以防止粘连。与圆柱形铣刀相比，这种类型的铣刀每英寸直径上的齿数更多，通常用于铣削较深的，狭窄的槽，并可以用于切割加工。磨削分类与无心磨削近20年来，人们对磨削加工的研究一直非常的感兴趣。一般来说，磨削是被用来作为精加工工序是产品道刀所要求的表面光洁度，正确的尺寸和精确的外形。但是，近期的研究表明磨削也可以像车削，铣削等加工方法那样很经济的利用于大量去除不需要的材料。磨削的分类磨削加工可以根据被磨削工件表面形状，磨床的类型或者磨削的产品类型进行分类，根据表面的类型和磨床的分类，分类如下：1 平面磨削：用于磨削平面。2 内圆，外圆磨削：用于磨削内外圆柱表面。3 无心磨削: 用于磨削内，外圆柱表面，在这一加工过程中，使用的磨床不同于常规的内外圆磨床。4 成型磨削：包括齿轮的磨削，螺纹磨削和花键轴磨削等等。5磨削切割加工：使用高速旋转的薄型的砂轮加工金属和非金属的材料。这种加工方法取决于磨粒的切割作用。在切割过程中，产生的热量有助于切割。6 砂带磨削：这种方法在磨削加工中被看作是一个重要的加工方法。由于砂带易于粘合零件的形状，因此，可以用来磨削平滑的，圆柱的和曲面的形状。7 手工磨削加工：在这一加工过程中，工件或者砂轮在手中，移动并加工。所用的机械有台式磨床，便携式磨床，模具磨床等。然而，对很多零件已设计出专用磨床，如曲轴磨床，凸轮磨床等等。在各种磨削加工中，可以根据磨制产品的类型，或根据磨床控制的类型作选择。例如：在圆柱磨削加工中，可以使用下列各种不同的类型的磨床：1普通外圆磨床。2重型平面或轧辊磨床。3万能外圆磨床。4 计算机数控外圆磨床。5 仿型磨床，如计算机控制的凸轮磨床。6 曲轴磨床。在现代计算机数控机床中，已经实现了砂轮自动修整和工件自动控制。无心磨削在无心磨削加工中，磨削圆柱时工件既不要像外圆磨床那样用顶尖住圆柱两个中心孔，也不要使用卡盘，圆柱形工件被支撑在砂轮，导轮和工件支架上，用于外圆表面的无心磨削。工件的旋转速度是由导轮的表面速度控制的。通过调节工件支架，工件的中心就可以保持在砂轮和导轮的中心连接线上。工件支架表面相对中心线有一倾角，其倾斜度和工件中心的高度时获得精确的圆柱表面的重要参数。外圆无心磨削为了加工不同外形的产品，工业上使用4种外圆无心磨削，这4种方法：1纵向进给贯穿式无心磨削。2横向进给无心磨削。3纵向定程进给无心磨削。4纵向和横向进给组合无心磨削。纵向进给加工用于普通圆柱形工件。控制轮轴相对对砂轮轴稍有倾斜。这样工件就可以获得两种类型的行动：即：1，绕自身轴的旋转；2 平行于砂轮轴的直线运动。由于第二种运动，工件可以从一侧进给，在磨削过程中，工件会移动到另一侧，因此这一加工过程能够自动化。横向进给加工用于阶梯圆柱体工件加工，这种工件不能贯穿进给，在这种情况下，导轮回退，送进工件，然后推进导轮，进行磨削加工。为了使所有直径都能够同步的进行磨削，砂轮和导轮应该具有类似步骤。纵向定程进给磨削加工用于圆锥形表面或仅仅在末端有一定的长度需要磨削的工件。横向和纵向进给组合用于阶梯轴的加工，其阶梯轴长度大于砂轮的宽度。内圆磨削，有两种加工方法，管状的工件放置在导轮，支撑轮和压辊之间，导轮，工件和砂轮的中心全都在相同的一条直线上，这种磨削就称作同心内圆无心磨削。在第二种加工方法中，工件也是支撑在导轮，支撑辊和加压辊之间，但是砂轮的中心并不位于导轮中心和工件中心的连接线上。这种磨削称作偏心内圆无心磨削。在第一种加工方法中，即使是非常薄的管状工件，其壁厚也能精确的研磨。附录2Turning, milling and grindingThe basic machines that are designed primarily to do turning, facing and boring are called lathes. Very little turning is done on other types of machine tools, and none can do it with equal facility. Because lathe can do boring, facing, drilling, and reaming in addition to turning, their versatility permits several operations to be performed with a single setup of the work piece. This account for the fact that lathes of various types are more widely used in manufacturing than any other machine tool.Lathes in various forms have existed for more than two thousand years. Modern lathes date from about 1797, when Henry Maudsley developed one with a lead screw. It provided controlled, mechanical feed of the tool. This ingenious Englishman also developed a change gear system that could connect the motions of the spindle and leads crew and thus enable threads to be cut.Lathe Construction. The essential components of a lathe are depicted in the block diagram of Fig.15. These are the bed, headstock assembly, tailstock assembly, carriage assemble, quick-change gear box, and the leads crew and feed rod.The bed is the backbone of lathe. It usually is made of well-normalized or aged gray or nodular cast iron and provides a heavy, rigid frame on which all the other basic components are mounted. Two sets of parallel, longitudinal ways, inner and outer, and contained on the bed, usually on the upper side. Some makers use an inverted V-shape for all four ways, whereas others utilize one inverted V and one flat ways intone or both set. Because several other components are mounted and /or move on the ways they must be made with precision to assure accuracy of alignment. Similarly, proper precaution should be taken in operating a lathe to assure that the ways are not damaged; any inaccuracy in them usually means that the accuracy of the entire lathe is destroyed. The ways on most modern lathes are surface hardened to offer greater resistance to wear and abrasion.The headstock is mounted in affixed position on the inner ways at one end of the lathe bed. It provides a provides a powered means of rotating the work at various speeds. It consists, essentially, of a hollow spindle, mounted in accurate bearings, and a set of transmission gearssimilar to a truck transmissionthrough which the spindle can be rotated at a number of speeds. Most lathes provide from eight to eighteen speeds, usually in a geometric ratio, and on modern lathes all the speeds can be obtained merely by moving from two to four levers. An increasing trend is to provide a continuously variable speed range through electrical or mechanical drives.Because the accuracy of a lathe is greatly dependent on the spindle, it is of heavy construction and mounted in heavy bearings, usually preloaded tapered roller or ball types, A longitudinal hole extends through the spindle so that long bar stock can be fed through it. The size of this hole is an important size dimension of a lathe because it determines the maximum size of bar stock that can be machined when the material must be fed through the spindle.The inner end of the spindle protrudes from the gear box and contains a means for mounting various types of chucks , face plates , and dog plates on it .Whereas small lathes often employ a threaded section to which the chucks are screwed, most large lathes utilize either cam-lock or key-drive taper noses . These provide a large-diameter taper that assures the accurate alignment of the chuck, and a mechanism that permits the chuck or face plate to be locked or unlocked in position without the necessity of having to rotate these heavy attachment.Power is supplied to the spindle by means of an electric motor through a V-belt or silent-chain drive. Most modern lathe has motors of from 5 to 15 horsepower to provide adequate power for carbide and ceramic tools at their high cutting speeds.The tailstock assembly consists, essentially, of three parts. A lower casting fits on the inner ways of the bed and can slide longitudinally thereon, with a means for clamping the entire assembly in any desired location. An upper casting fits on the lower one and can be moved transversely upon it on some type of keyed ways. The transverse motion permits aligning the tailstock and headstock spindles and provides a method of turning tapers .The third major component of the assembly is the tailstock quill. This is a hollow steel cylinder, usually about 2 to 3 inches in diameter, that can be moved several inches longitudinally in and out of the upper casting by means of a hand wheel and screw. The open end of the quill hole terminates in a Morse taper in which a lathe center, or various tools such as drills, can be held. A graduated scale, several inches in length, usually is engraved on the outside of the quill to aid in controlling its motion in and out of the upper casting. A locking device permits clamping the quill in any desired position.The carriage assembly provides the means for mounting and moving cutting tools. The carriage is a relatively flat H-shaped casting that rests and moves on the outer set of ways on the bed. The transverse bar of the carriage contains ways on which the cross slide is mounted and can be moved by means of a feed screw that is controlled by a small hand wheel and a graduated dial. Through the cross slide is a means is provided for moving the lathe tool in the direction normal to the axis of rotation of the work.On most lathes the tool post actually is mounted on a compound rest .This consists of a base, which is mounted on the cross slide so that it can be pivoted about a vertical axis, and an upper casting. The upper casting is mounted on ways on this base so that it can be moved back and forth and controlled by means of a short lead screw operated by a hand wheel and a calibrated dial.Manual and powered motion for the carriage, and powered motion for the cross slide, is provided by mechanisms within the apron, attached to the front of the carriage. Manual movement of the carriage along the bed is effected by turning a hand wheel on the front of the apron, which is geared to a pinion on the back side. This pinion engages a rack that is attached beneath the upper front edge of the bed in an inverted position.To impart powered movement to the carriage and cross slide, a rotating feed rod is provided. The feed rod, which contains a keyway throughout most of its length, passes through the two reversing bevel pinions and is keyed to them. Tighter pinion cam be brought into mesh with a mating bevel gear by means of the reversing lever on the front of the apron and thus provide “forward” or “reverse” power to the carriage. Suitable clutches connect either the rack pinion or the cross-slide screw to provide longitudinal motion of the carriage or transverse motion of cross slide.For cutting threads, a second means of longitudinal drive is provided by a lead screw. Whereas motion of the carriage when driven by the feed-rod mechanism takes place through affrication clutch in which slippage is possible, motion through the lead screw is by a direct, mechanical connection between the apron an the lead screw. This is achieved by a split nut. By means of a clamping lever on the front of the apron, the split nut can be closed around the lead screw. With the split nut closed, the carriage is moved along the lead screw by direct without possibility of slippage.Modern lathes have a quick-change gear box. The input end of this gear box is driven from the lathe spindle by means of suitable gearing. The output end of the gear box is connected to the feed rod and lead screw. Thus through this gear train, leading from the spindle to the quick-change gear box. Thence to the lead screw and feed rod, and then to the carriage, the cutting tool can be made to move a specific distance, either longitudinally or transversely, of each revolutions of the spindle. A typical lathe provides, through the feed rod, forty-eight feeds ranging from 0.002 inch to 0.118 inch per revolution of the spindle, and, through the lead screw, leads for cutting forty-eight different threads from 1.5 to 92 per inch. On some older and some cheaper lathes, one or two gears in the gear train between the spindle and the change gear box must be changed in order to obtain a full range of threads and feed. Milling is basic machining process in which the surface is generated by the progressive formation and removal of chips of material from the work piece as it is fed to a rotating cutter in a direction perpendicular to the axis of the cutter. In some cases the work piece is stationary and the cutter is fed to the work .In most instances a multiple-tooth cutter is used so that the metal removal rate is high and frequently the desired surface is detained in a single pass of the work.The tool used in milling is known as a milling cutter. It usually consists of a cylindrical body which rotates on its axis and contains equally spaced peripheral teeth that intermittently engage a cut the work piece. In semen cases the teeth extend part way across one or both ends of the cylinder. Because the milling principle provides rapid metal removal and can produce good surface finish, it is particularly well-suited for mass-production work, and excellent milling machine have been developed for this purpose . However, very accurate and versatile milling shop and tool and die work. A shop that is equipped with a milling machine and an engine lathe can machine almost any type of product of suitable size. Types of milling operations. Milling operations can be classified into two broad categories, each of which has several variations:1 In peripheral milling a surface is generated by teeth located in the periphery of the cutter body; the surface is parallel with the axis of rotation of the cutter. Both flat and formed surfaces can be produced by this method. The cross section of the resulting surface corresponds to the axial contour of the cutter. This procedure often is called slab milling.2 In face milling the generated flat surface is at right angles to the cutter axis and is the combined result of the actions of the portions of the teeth locate4d on both the periphery and the face of the cutter . The major portion of the cutting is done by the peripheral portions of the teeth with the face portion of the cutting is done by the peripheral portions of the teeth with the face portions providing a finishing actionThe basic concepts of peripheral and face milling are illustrated in fig.16-1.peripheral milling operations usually are performed on machines having horizontal spindles, whereas face milling is done on both horizontal an vertical spindle machines.Surface generation in milling. Surfaces can be generated in milling by two distinctly different methods depicted in fig. note that in up milling the cutter rotates against the direction of feed the work piece, whereas in down milling the rotation is the same direction as the feed. A shown in fig16-2, the method of chip formation is quite different in the two cases. In up milling the c hip is very thin at the beginning, where the tooth first contacts the work, and increase in thickness, becoming a maximum where the tooth leaves the work. The cutter tends to push the work along and lift it upward from the table. This acting tends to eliminate any effect of looseness in the feed screw and nut of the milling machine table and results in a smooth cut. However, the action also tends to loosen the work from the clamping device so that greater clamping forcers must be employed. In addition the smoothness of the generated surface depends greatly on the sharpness of the cutting edges.In down milling, maximum chip thickness occurs close to the pint at which the tooth contacts the work. Because the relative motion tends to pull the work piece into the cutter, all possibility of looseness in table feed screw must be eliminated if down milling is to be used. It should never be attempted on machines that are not designed for this type of milling. Inasmuch as the material yields in approximately a tangential direction at the end of the tooth engagement, there is much less tendency for the machined surface to show tooth marks than when up milling is used. A nether considerable advantage of down milling is thee the cutting force tends to hold the work against the machine table, permitting lover clamping force to be employed. This is particularly advantageous when milling thin work piece or when taking heavy cuts.Sometimes a disadvantage of down milling is that the cutter teeth strike against the surface of the work at the beginning of each chip. When the work piece has a hard surface, such as casting do, this may cause the teeth to dull rapidly.Milling cutters. Milling cutters can be classified several ways one method is to group them into two broad classes, based on tooth relief, as follows:1 Profile-cutters have relief provided on each tooth by grinding a small land back of the cutting edge. The cutting edge may be straight or curved.2 In form or cam-relieved cutters the cross section of each tooth is an eccentric curve behind the cutting edge, thus providing relief. All sections of the eccentric relief, parallel with the cutting edge, must have the same contour as the cutting edge; cutters of these types are sharpened by grinding only the face of the teeth, with the contour of the cutting edge thus remaining unchanged.Another useful method of classification is according to the method of mounting the cutter. Arbor cutters are those the have a center hole so they can be mounted on an arbor. Shank cutters have either tapered or straight integral shank. Those with tapered shanks can be mounted directly in the milling machine spindle, whereas straight-shank cutters are held in a chuck. Facing cutters usually are bolted to the end of a stub arbor.The common types of milling cutters, classified by this system are as follows:Arbor cutter Plain angleSide inserted-toothStaggered-tooth formMetal-slitting saw flyShank cutter End mills t-slitSolid woodruff key seatShell flyHollow Types of milling cutters. Plain milling cutters are cylindrical or sick-shaped, having straight or helical teeth on the periphery, they are used for milling that surfaces this type of operation is called plain or slab milling, each tooth in a helical cutter engages the work gradually, and usually more than one tooth cuts at give time, this reduces shock and chattering tendencies and promotes a smoother surface. Consequently, this type of cutter usually is preferred over one with straight teeth.Side milling cutter are similar to plain milling cutters except that the teeth extend radically part way across one or both ends of the cylinder toward the center, the teeth may be either straight or helical. Frequently these cutters are relatively narrow, being dislike in shape. Two or more side milling cutters often are spaced on an arbor to make simultaneous, parallel cut, in an operation called straddle milling. Interlocking slotting cutters consist of woo cutters similar to side mills, but made to operate as a unit for milling slots .the two cutters are adjuster to desired width by inserting shims between them. Staggered-tooth milling cutter are marrow cylindrical cutters having staggered teeth, and with alternate teeth having opposite helix angles, they are ground to cut only on the periphery, but each tooth also has chip clearance ground on the protruding side, these cutters have a free cutting action that makes them particularly effective in milling deep slots. Metal-slitting saws are thin, plain milling cutter, usually from 1/32 to 3/16 inch thick, which have their sides slightly “dished” to provide clearance and prevent binding, they usually have more teeth per inch of diameter than ordinary plain milling cutters and are used for milling deep, narrow slots and for cutting-off operations.Grinding classification and centre less grinding Since the last two decades, there has been an increased interest in the investigation of grinding processes. Generally, grinding is used an a finishing process to get the desired surface finish, correct size and accurate shape of the product. However recent researches have like turning, miling, etc.Classification of grinding processes Grinding processes may be classified according to the shape of the surface that is ground, type of grinding machine used or type of the ground product. According to the type of surface and type of machine, the following classification is abstained.1Surface grinding is used for grinding flat surfaces.2Cylindrical grinding is used for grinding external and internal cylindrical surfaces.3Centre less grinding is used for the grinding of external and internal cylindrical surfaces. In these processes machines are different from those used for conventional cylindrical grinding.1Form grinding includes the grinding of gears, thread grindings and grinding of splints etc.2The abrasive cut-off process is used for severing metallic and nonmetallic materials with the help of thin grinding wheels rotating at high speed; the process depends on the cutting action of abrasive particles. The process is assisted by the great produced by the cutting action.3Abrasive belt grinding has acquired an important place in grinding processes. It can be used to grind gloat, cylindrical or curved shapes as the belt can be easily made to conform to the shape of the component.4Off-hand grinding processes are those in which work piece or grinding wheel is held by hand and guided and forced to carry out the grinding process. Machines like bench grinders, portable grinders, die grinders,etc,are used for the purpose,However there are many products for which special grinding machines have been designed, such as crank shaft grinding machine, camshaft grinding machine, etc.In each category of grinding process, variations are there according to the type of product to be ground or according to the type of controls provided with the machine. Thus, for example, in cylindrical grinding, the following different types of machine are manufactured.1plain cylindrical grinding machines,2Heavy plain or roll grinding machines.3universal cylindrical grinding machines, 4CNC cylindrical grinder,5contour girding machines such as computer controlled cam grinder, and6grand shaft grinding machines In modern CNC machines automatic machines automatic control of work piece dimensions as well as facility of automatic dressing of grinding wheel are provided.Genderless grinding

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