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外文资料
Herbert W. Yankee Manufacturing Processes [M] Prentice-Hall Inc., 1979
Medium-Production Lathes
Duplicating Lathe: Duplicating (or tracer) lathes are designed to produce duplicate parts by semiautomatic means. Except f tape-controlled lathes (discussed in Chapter 21), the operator is required to load and unload the work pieces and to start the automatic operation for each cutting cycle. One single-point cutting tool is used. Straight, tapered, and contoured turned or faced surfaces and bored holes are repetitively produced by the motion of a stylus as it follows the outline of a low-cost template. The template is generally mounted at the rear of the machine. The movements of the stylus are actuated by mechanical, air, hydraulic, or electrical methods. Work may be held between centers or chucked. Duplicating or tracer attachments are generally factory-installed on a standard engine lathe, although special machines are also available.
Turret Lathe: Turret lathes are semiautomatic machine tools which can produce parts in greater quantities, to closer tolerances, faster, and as a result more economically than is possible by conventional engine lathes. Unlike the engine lathe, the turret lathe is not restricted to a single cutting tool. A leading advantage is that several operations may be performed on a work pace at a given time. It should be noted, however, that the range and types of turret lathe operations are essentially the same as those associated with the engine lathe.
FIGURE 16-6 Turret lathe production part (Courtesy, Jones Lamson)
Figure 16-6 illustrates examples of turret lathe production parts. To offset the need for frequent tool changes, a six-sided turret is used in place of a tailstock. The turret may easily be indexed so that any desired cutting tool may contact the work piece. Additional cutting tools may be placed in square turrets on the cross slide and may be readily indexed to machine other surfaces. Unlike a cutting tool used on an engine lathe, once turret lathe tools have been properly inserted in one of the various tooling stations, they need not be remove until they require sharpening or after the production run has been completed. Finally, there is also available a single tool holder on a turret lathe which is mounted with a cutting tool on the rear of the cross slide.
Full advantage of the versatility and adaptability of the engine lathe can be obtained only in cases where the services of a highly skilled machinist are available. Skilled labor is expensive. Parts produced by engine lathe operations are usually more costly than similar parts produced on a turret lathe. Turret lathe production costs are often minimized by using skilled setup men whose job it is to set and adjust the tools, leaving the simple and repetitive operations for the lower-pay-scale machine operators.
FIGURE 16-7 Ram-type universal turret lathe( Courtesy, Jones Lamson)
Turret lathes may be classified as horizontal and vertical. The two leading types of horizontal turret lathes are ram type, shown in Figure 16-7, and the saddle type. Both types are suited to bar(cylindrical turning) and chucking work. The ram-type turret lathe is best suited for light bar work and small chucking jobs, while the saddle-type turret lathe is primarily used for longer bar work and for heavier chucking work pieces. Figure 16-8 shows a numerically controlled four-axis turret lathe. Ideal for bar and chucking work, they can also handle between-centers shaft work.
FIGURE 16-8 A four-axis numerically controlled turret lathe( Courtesy, Giddings Lewis-Bickford Machine Compangy)
Vertical turret lathes are designed for considerably larger and heavier work than is commonly associated with either type of horizontal turret lathes. Vertical machines are utilized solely for complex chucking work, particularly for boring operations, and are not adapted to bar work. An example of a vertical turret is shown in Figure 16-9.
FIGURE16-9 A vertical turret lathe with a 36 in. diameter table (Courtesy, The Bullard Company)
High-Production Lathes
It is difficult to precisely classify the various types of turning machines strictly according to their production output, Machines previously discussed are all reasonably similar, in that each type requires operator attention to an extent that varies form “considerable” to “only occasional.” The types of high-production lathes selected for following discussion are those that run almost continuously. Sones are fully automatic and require only occasional operator attention.
Automatics Screw Machines: Automatic screw machines (or automatic bar machines) were originally designed for the high production of screws and various other threaded fasteners. The basic beginnings of this machine date back to the 1880s, when the first machine was developed. The machine is essentially an advanced form of a turret lathe which fashions a wide range of parts is large quantities form bar stock. High output of intricate mechanisms designed to automatically feed single and continuous lengths of stock, index the turret for the desired sequence of the proper cutting tools, and retract the tool after cutting. Contrary to the designation “screw machine,” production is not limited to threaded parts. The process is adaptable to the economical production of turned and formed parts of almost unlimited configuration, as shown in Figure 16-10.
FIGURE 16-10 Typical Brown Sharp produced on a screw machine ( Courtesy, e Manufacturing Co.)parts
FIGURE 16-11 A single spindle screw machine (Courtesy. Brown Sharpe Manufacturing Co.)
FIGURE 16-12 A close-up view of cutting tools in a six-station turret ( Courtesy, Brown Sharpe Manufacturing Co.)
A automatic screw machines may be classified as single-spindle automatics，multiple-spindle automatics, and automatic chucking machines. An example of a single-spindle bar automatic screw machine is shown in Figure 16-11. Bar stock (ranging from round, square , hexagonal, or other cross-sectional shapes) is fed through a revolving hollow spindle at the beginning of each cycle of operation. The stock is stopped at a predetermined distance and held during the cutting operations in a cullet. Cutting tools are mounted around a six-station turret shown in Figure 16-12, which rotates in a vertical plane in a Ferris wheel motion. The turret is fixed to a slide which gives it longitudinal movement. There is a cross slide on which additional tools may be mounted in positions on the front as well as to the rear. The various cutting tool movements are obtained by means of cams mounted on shafts which are geared together on three sides of the machine. Mounted “dogs” engage various trip levers to control the sequence of operations on the machine.
FIGURE 16-13(a) A Vertical chucking machine ( Courtesy, The Bullard Co.)
FIGURE 16-13(b) A horizontal chucking machine ( Courtesy, The Warner Swazi Co.)
The principles that apply to the tolling arrangement of single-spindle-bar automatic screw revolving work spindle. The spindle carrier indexes and automatically moves the stock from one cutting station to another. The required cutting operations are machines apply ascrew machines. Instead of a single spindle, however, spindle machines may havlso to multiple-spindle-bar automatic e four, five, six, or eight hollow spindles. Bars of stock are loaded into each continuously performed on the stock in progressive stages as the work piece proceeds from one station to another, ending with the completed part as it is cut off from its original bar. Figure 16-13a and illustrates two types of chucking machines designed for machining castings, forgings, pressed parts, and other shapes that cannot be machined from bar stock. Automatic chucking machines are capable of performing most of the operations normally associated with the multiple-spindle-bar automatics machine. A numerically controlled two-axis twin-turret bar chucker is shown in Figure 16-14. It is common practice for an operator to handle or service two or more automatic machines once they have been properly tooled. Figure 16-15 illustrates some typical parts machined on a vertical chucking machine.
FIGURE 16-14 Two-axis twin bar checkers are well suited for either bar or chucking work This machine has a 14 tool capacity that inherently reduces tool-changing time. ( Courtesy, Giddings Lewis-Bickford Machine Co.)
FIGURE 16-15 Typical parts machined on a vertical chucking machine . (Courtesy, The Warner Swasay Co.)
FIGURE 16-16 A Swiss-automatic screw machine (Courtesy, American Belcher Corporation)
FIGURE 16-17 A close-up view showing the tooling and the slides on a Swiss automatic screw machine ( Courtesy, American Belcher Corporation)
Swiss-Type Automatic Screw Machine：An example of a Swiss-type automatic screw machine is shown in Figure 16-16, with a close up in the tooling and slides in Figure 16-17.It differs widely in design and function from other types of screw machines. A revolving piece of –stock is fed through a carbide-lined guide bushing into the path of five radically, mounted tools which are individually cam-controlled. edges of the single-point cutting tools which are used in this process are set to contact the stock as close as a few thousands of an inch but never more than in (0.794 mm) away from the end of the guide bushing. Accurate parts may be produced in this manner because the firmly held work is prevented from springing away form the cutting tool. Special combining such as tapers and multiple diameters are possible by combining the forward or dwell movements of the headstock and the in –and –out tool movements.
FIGURE 16-18 Examples of Swiss automatic machine production parts ( Courtesy, American Belcher Corporation )
中文译文
中等生产率的车床
仿形车床: 仿形车床是为了通过半自动的方法生产完全一样的零件而被设计的，除了程序控制车床（详见21章），装上、卸下工件以及每个切割周期自动运转的启动是需要由操作员完成的。使用一个单切削刀具，模板通常装在机器的后部。通过机械、空气、水压、或者电的方法促使触针的移动，尽管专门的机床也是可以的，但是仿形车床的附件出厂时一般都安装在一个标准的普通车床上。
转塔车床：转塔车床是半自动的机床，它比常规的发动机车床生产的零件数量更大，公差更小，速度快所以经济要更好。不同于发动机车床，转塔车床不局限于单一的切削工具。他最主要的优点是有些操作可以在给足时间完成工件的加工。
图16-6 转塔机床生产零件（经琼斯和拉姆森同意转载）
图16-6是转塔车床生产零件的实例。用一个方面的小塔代替尾座，是为了抵消频繁换刀。然而，应该注意的是转塔车床操作范围和类型与发动机车床基本上是相同的。最后转塔车床上的单一工具架也可以带着切削工具安装在后部的横向滑块上。
普通车床的通用性和适应性只有在熟练的机械师的情况下能被充分利用，熟练工是昂贵的。有发动机车床操作下生产的零件比转塔车床生产相同的零件花费要多。将转塔车床生产成本减到最少的方法是让熟练的安装工人设置和调整工具，让低工资等级的机器操作员进行简单重复的操作。
转塔车床可分为卧式和立式两类。卧式转塔车床的两种主要类型是鞍座式和滑块式（见图16-7）两种类型都适合车削和卡盘工作。滑块式转塔车床最合适于轻的棒状加工以及小的卡盘工作而鞍座式转塔车床主要用于加工较长的棒状工件以及较重的卡盘的工件。图16-8是四轴数控转塔车床。理想的棒状以及卡盘的车削加工是它们也可以操作中心与轴之间的工作。块从一个站到另一个收益,以完成的部分,因为它是切断了从原来的地点计的机器加工铸件、锻件、挤压零件和其他形状,不能加工棒料。
图16-7常规的滑块式转塔车床（经琼斯和拉姆森同意转载）
图16-8 四轴数控转塔车床（经吉丁斯和刘易斯—比其福德公司同意转载）
立式车床是为了较大和较重的工作而被设计的，它与卧式车床的两周类型有关联。立式车床可以单独完成复杂的卡盘工作，特别是钻孔操作，不适应棒状物的操作。图16-9是立式车床的实例。
36mm工作台的立式车床（经布拉得公司同意转载）
高产车床
严格按照不同的产品输出是很难准确划分机床的类型。前面讨论的机器都是相当类似的，因为某周类型的机器都需要操作员注意到从“可观的”到“偶尔”的程度。下面选择讨论的高产车床的类型几乎是可以连续运行的。有些是全自动的，只需要操作员偶尔注意。
自动螺纹车床：自动螺纹车床最初是被设计用于高产量的螺钉和其他螺纹紧固件的生产。自动螺纹车床的开发可以追溯到19世纪80年代。自动螺纹车床基本上是转塔车床的高级形式，它可以把棒料形成大批量且范围广的零件。可互换的高输出可能是由于被设计用来自动单次和连续送料的复杂的机械装置，合适的切削工具的顺序以及切割后的回收工具。这个进程无限的配置部分生产和形成的经济生产。与螺纹车床的命名相反，它的生产并不仅限于螺纹零件。
图16-10 螺纹车床生产的典型零件（经布朗和夏普制造有限公司同意转载）
图16-11 单轴螺纹车床（经布朗和夏普制造有限公司同意转载）
图16-12卡工位刀架切削工具的特写（经布朗和夏普制造有限公司同意转载）
自动螺纹车床可分为单轴自动车床，多轴自动车床，自动加紧机。图16-11是单轴螺纹车床。棒形刚才的进料是通过每个操作周期开始的一个转轴的空间轴。钢材在预定的距离停止并且在简夹的切割操作中被控制。如图16-12所示，切削工具安装在卡工位的刀架上，它可以在费力思的车轮运动的垂直平面内旋转。小塔固定是在一个滑坡上，这使得它能在纵向运动。额外的工具可以安装在十字滑坡的前面和后面。这种运动能保证水平位置和竖直位置不受偏差的影响。各种工具的运用是由安装在轴上的凸轮与机器的三个侧面与齿轮相连的方法获得的。安装的“电子狗”与不同的跳闸杠杆啮合来控制机器的操作顺序。是操作更加简便，出现错误时能够及时发现。
图16-13（a）垂直夹紧机 （经布拉德有限公司同意转载）
图16-13（b）水平夹紧机（经华纳和斯瓦西有限公司同意转载）
适用于单锭杆自动螺纹车床模具排列的原则也适用于多锭杆自动螺纹车床。棒状钢材被加载到每个连续转转的工件主轴。然而，多轴车床不是一个单一的主轴，它可能有四个、五个、六个或八个空心主轴。图16-13a和b说明了加进机的两种类型设计加工的铸件，锻件，冲压件，以及其他不能从棒料加工的形状。自动夹紧机能够进行大多数与多主轴棒料自动机器相关操作。图16-14所示的数控两轴的双转塔杆卡盘车床。一旦操作员使用工确的工具加工，一个操作员操作或者维护两个或以上的自动车床是常规的做法。图16-15显示了一些垂直夹紧机的典型零件。
图16-14 两轴双杆卡盘车床适合棒料或卡盘加工这种车床有14个可以放刀具的地方，从本质上减少了换刀时间经吉丁斯和刘易斯—比其福德公司同意转载）
图16-15 垂直夹紧机加工的典型零件（经华纳和斯瓦西有限公司同意转载）
图16-16 瑞士自动螺纹车床（经美国贝奇勒公司同意转载）
图16-17瑞士自动螺纹车床加工和滑坡的特写镜头（经美国贝奇勒公司同意转载）
瑞士式自动螺丝机:一个瑞士式自动螺丝机如图并且,靠近在工具和幻灯片在图16 - 17日。它与广泛的在设计和功能从其他类型的螺丝机。一个旋转块股票是美联储通过硬质合金衬导套的道路五个彻底,安装工具单独凸轮控制。切削刃的单点切削工具用于这个过程将接触股票接近几千英寸但不会超过在(0.794毫米)远离结束的导套。准确的零件可能产生在这种方式,因为坚定的工作是阻止起拱远离刀具。特别结合如蜡烛和多个直径可能结合的运动向前或住床头,和动作两工具。
图16-18瑞士自动车床生产零件的例子（经美国贝奇勒公司同意转载）
