英文文献翻译

Lathe and Turning

The Lathe and Its Construction

A lathe is a machine tool used primarily for producing surfaces of revolution and flat edges.

Based on their purpose, construction, number of tools that can simultaneously be mounted, and degree of automation, lathes-or, more accurately, lathe-type machine tools can be classified as follows: (1)Engine lathes (2)Toolroom lathes (3)Turret lathes

(4)Vertical turning and boring mills (5)Automatic lathes

(6)Special-purpose lathes

In spite of that diversity of lathe-type machine tools, they all have common features with respect to construction and principle of operation. These features can best be illustrated by considering the commonly used representative type, the engine lathe. Following is a description of each of the main elements of an engine lathe, which is shown in Fig.11.1. Lathe bed.

The lathe bed is the main frame, involving a horizontal beam on two vertical supports. It is usually made of grey or nodular cast iron to damp vibrations and is made by casting. It has guideways to allow the carriage to slide easily lengthwise. The height of the lathe bed should be appropriate to enable the technician to do his or her job easily and comfortably. Headstock.

The headstock is fixed at the left hand side of the lathe bed and includes the spindle whose axis is parallel to the guideways (the slide surface of the bed). The spindle is driven through the gearbox, which is housed within the headstock. The function of the gearbox is to provide a number of different spindle speeds (usually 6 up to 18 speeds). Some modern lathes have headstocks with infinitely variable spindle speeds, which employ frictional ,electrical ,or hydraulic drives.

The spindle is always hollow, i. e., it has a through hole extending lengthwise. Bar stocks can be fed through that hole if continuous production is adopted. Also, that hole has a tapered surface to allow mounting a plain lathe center. The outer surface of the spindle is threaded to allow mounting of a chuck, a face plate, or the like. Tailstock.

The tailstock assembly consists basically of three parts, its lower base, an intermediate part, and the quill. The lower base is a casting that can slide on the lathe bed along the guideways, and it has a clamping device to enable locking the entire tailstock at any desired location, depending upon the length of the workpiece. The intermediate part is a casting that can be moved transversely to enable alignment of the axis of the tailstock with that of the headstock. The third part, the quill, is a hardened steel tube, which can be moved longitudinally in and out of the intermediate part as required. This is achieved through the use of a handwheel and a screw, around which a nut fixed to the quill is engaged. The hole in the open side of the quill is tapered to enable mounting of lathe centers or other tools like twist drills or boring bars. The quill can be locked at any point along its travel path by means of a clamping

device.

The carriage.

The main function of the carriage is mounting of the cutting tools and generating longitudinal and/or cross feeds. It is actually an H-shaped block that slides on the lathe bed between the headstock and tailstock while being guided by the V-shaped guideways of the bed. The carriage can be moved either manually or mechanically by means of the apron and either the feed rod or the lead screw.

When cutting screw threads, power is provided to the gearbox of the apron by the lead screw. In all other turning operations, it is the feed rod that drives the carriage. The lead screw goes through a pair of half nuts, which are fixed to the rear of the apron.When actuating a certain lever, the half nuts are clamped together and engage with the rotating lead screw as a single nut, which is fed, together with the carriage, along the bed. When the lever is disengaged, the half nuts are released and the carriage stops.On the other hand, when the feed rod is used, it supplies power to the apron through a worm gear. The latter is keyed to the feed rod and travels with the apron along the feed rod, which has a keyway extending to cover its whole length.A modern lathe usually has a quick-change gearbox located under the headstock and driven from the spindle through a train of gears. It is connected to both the feed rod and the lead screw and enables selecting a variety of feeds easily and rapidly by simply shifting the appropriate levers. The quick-change gearbox is employed in plain turning, facing and thread cutting operations. Since that gearbox is linked to the spindle, the distance that the apron (and the cuttingtool) travels for each revolution of the spindle can be controlled and is referred to as the feed.

Lathe Cutting Tools

The shape and geometry of the lathe tools depend upon the purpose for which they are employed.Turning tools can be classified into two main groups, namely, external cutting tools and internal cutting tools. Each of these two groups include the following types of tools: Turning tools.

Turning tools can be either finishing or rough turning tools. Rough turning tools have small nose radii and are employed when deep cuts are made. On the other hand, finishing tools have larger nose radii and are used for obtaining the final required dimensions with good surface finish by making slight depths of cut. Rough turning tools can be right-hand or left-hand types, depending upon the direction of feed. They can have straight, bent, or offset shanks. Facing tools.

Facing tools are employed in facing operations for machining plane side or end surfaces. There are tools for machining left-hand-side surfaces and tools for right-hand-side surfaces. Those side surfaces are generated through the use of the cross feed, contrary to turning operations, where the usual longitudinal feed is used. Cutoff tools.

Cutoff tools, which are sometimes called parting tools, serve to separate the workpiece into parts and/or machine external annular grooves. Thread-cutting tools.

Thread-cutting tools have either triangular, square, or trapezoidal cutting edges, depending upon the cross section of the desired thread. Also, the plane angles of these tools must always be identical to those of the thread forms. Thread-cutting tools have straight shanks for external thread cutting and are of the bent-shank type when cutting

internal threads. Form tools.

Form tools have edges especially manufactured to take a certain form, which is opposite to the desired shape of the machined workpiece.An HSS tool is usually made in the form of a single piece, contrary to cemented carbides or ceramic, which are made in the form of tips. The latter are brazed or mechanically fastened to steel shanks．Fig.11.2 indicates an arrangement of this latter type, which includes the carbide tip, the chip breaker, the pad, the clamping screw (with a washer and a nut), and the shank.As the name suggests, the function of the chip breaker is to break long chips every now and then, thus preventing the formation of very long twisted ribbons that may cause problems during the machining operation. The carbide tips (or ceramic tips) can have different shapes, depending upon the machining operations for which they are to be employed. The tips can either be solid or with a central through hole, depending on whether brazing or mechanical clamping is employed for mounting the tip on the shank. Lathe Operations

In the following section, we discuss the various machining operations that can be performed on a conventional engine lathe.It must be borne in mind, however, that modern computerized numerically controlled lathes have more capabilities and can do other operations, such as contouring, for example. Following are conventional lathe operations.

Cylindrical turning.

Cylindrical turning is the simplest and the most common of all lathe operations. A single full turn of the workpiece generates a circle whose center falls on the lathe axis; this motion is then reproduced numerous times as a result of the axial feed motion of the tool. The resulting machining marks are, therefore, a helix having a very small pitch, which is equal to the feed. Consequently, the machined surface is always cylindrical.The axial feed is provided by the carriage or the compound rest, either manually or automatically, whereas the depth of cut is controlled by the cross slide.In roughing cuts, it is recommended that large depths of cuts (up to 0.25in. or 6mm, depending upon the workpiece material) and smaller feeds would be used. On the other hand, very fine feeds, smaller depths of cut (less than 0.05in, or 0.4mm), and high cutting speeds are preferred for finishing cuts. Facing.

The result of a facing operation is a flat surface that is either the whole end surface of the workpiece or an annular intermediate surface like a shoulder. During a facing operation, feed is provided by the cross slide, whereas the depth of cut is controlled by the carriage or compound rest. Facing can be carried out either from the periphery inward or from the center of the workpiece outward. It is obvious that the machining marks in both cases take the form of a spiral.

Usually, it is preferred to clamp the carriage during a facing operation, since the cutting force tends to push the tool (and, of course, the whole carriage) away from the workpiece. In most facing operations, the workpiece is held in a chuck or on a face plate.

Groove cutting.

In cut-off and groove-cutting operations, only cross feed of the tool is employed. The cut-off and grooving tools, which were previously discussed, are employed.

Boring and internal turning.

Boring and internal turning are performed on the internal surfaces by a boring bar or suitable internal cutting tools. If the initial workpiece is solid, a drilling operation must be performed first. The drilling tool is held in the tailstock, and the latter is then fed against the workpiece. Taper turning.

Taper turning is achieved by driving the tool in a direction that is not parallel to the lathe axis but inclined to it with an angle that is equal to the desired angle of the taper. Following are the different methods used in taper-turning practice:

(1) Rotating the disc of the compound rest with an angle equal to half the apex angle of the cone. Feed is manually provided by cranking the handle of the compound rest. This method is recommended for taper turning of external and internal surfaces when the taper angle is relatively large.

(2) Employing special form tools for external, very short, conical surfaces. The width of the workpiece must be slightly smaller than that of the tool, and the workpiece is usually held in a chuck or clamped on a face plate. In this case, only the cross feed is used during the machining process and the carriage is clamped to the machine bed.

(3) Offsetting the tailstock center. This method is employed for external taper turning of long workpieces that are required to have small taper angles (less than 8°). The workpiece is mounted between the two centers; then the tailstock center is shifted a distance S in the direction normal to the lathe axis.

(4) Using the taper-turning attachment. This method is used for turning very long workpieces, when the length is larger than the whole stroke of the compound rest. The procedure followed in such cases involves complete disengagement of the cross slide from the carriage, which is then guided by the taper-turning attachment.

During this process, the automatic axial feed can be used as usual. This method is recommended for very long workpieces with a small cone angle, i.e., 8°through 10°. Thread cutting.

When performing thread cutting, the axial feed must be kept at a constant rate, which is dependent upon the rotational speed (rpm) of the workpiece. The relationship between both is determined primarily by the desired pitch of the thread to be cut.As previously mentioned, the axial feed is automatically generated when cutting a thread by means of the lead screw, which drives the carriage. When the lead screw rotates a single revolution, the carriage travels a distance equal to the pitch of the lead screw. Consequently, if the rotational speed of the lead screw is equal to that of the spindle (i.e., that of the workpiece), the pitch of the resulting cut thread is exactly equal to that of the lead screw. The pitch of the resulting thread being cut therefore always depends upon the ratio of the rotational speeds of the lead screw and the spindle:

Pitch of the lead screw/ Desired pitch of workpiece=rpm of the workpiece/rpm of lead screw=spindle-to-carriage gearing ratio.

This equation is useful in determining the kinematic linkage between the lathe spindle and the lead screw and enables proper selection of the gear train between them.

In thread cutting operations, the workpiece can either be held in the chuck or mounted between the two lathe centers for relatively long workpieces. The form of the tool used must exactly coincide with the profile of the thread to be cut, i.e., triangular tools must be used for triangular threads, and so on. Knurling.

Knurling is mainly a forming operation in which no chips are produced. It involves

pressing two hardened rolls with rough filelike surfaces against the rotating workpiece to cause plastic deformation of the workpiece metal.

Knurling is carried out to produce rough, cylindrical (or conical) surfaces, which are usually used as handles. Sometimes, surfaces are knurled just for the sake of decoration; there are different types of patterns of knurls from which to choose. Cutting Speeds and Feed

The cutting speed, which is usually given in surface feet per minute (SFM), is the number of feet traveled in the circumferential direction by a given point on the surface (being cut) of the workpiece in 1 minute.

The relationship between the surface speed and rpm can be given by the following equation: SFM=πDN Where

D=the diameter of the workpiece in feet N=the rpm

The surface cutting speed is dependant primarily upon the material being machined as well as the material of the cutting tool and can be obtained from handbooks, information provided by cutting tool manufacturers, and the like. Generally, the SFM is taken as 100 when machining cold-rolled or mild steel, as 50 when machining tougher metals, and as 200 when machining softer materials. For aluminum, the SFM is usually taken as 400 or above. There are also other variables that affect the optimal value of the surface cutting speed. These include the tool geometry, the type of lubricant or coolant, the feed, and the depth of cut. As soon as the cutting speed is decided upon, the rotational speed (rpm) of the spindle can be obtained as follows:

N=SFM/(πD)

The selection of a suitable feed depends upon many factors, such as the

required surface finish, the depth of cut, and the geometry of the tool used. Finer feeds produce better surface finish, whereas higher feeds reduce the machining time during which the tool is in direct contact with the workpiece.Therefore, it is generally

recommended to use high feeds for roughing operations and finer feeds for finishing operations. Again, recommended values for feeds, which can be taken as guidelines, are found in handbooks and in information booklets provided by cutting tool manufacturers.

车床和车削 车床及

车床是机床用于生产和平面边缘表面为主。

根据他们的目的，施工，可同时安装工具的数量，自动化程度，车床，或者更准确地说，车床型机床可分为如下： （1）发动机车床 （2）工具间车床 （3）转塔车床 （4）立式车床镗床 （5）自动车床 （6）专用车床

对该项车床型机床多样性尽管如此，他们都与尊重的建设和运作原则的共同特点。这些功能可以最好的说明，考虑常用的代表类型，发动机车床。以下是对一个普通车床，这是Fig.11.1所示的主要内容每个描述。 车床的床。

车床的床身是主框架，涉及两个垂直支撑横梁。它通常是采用灰铸铁或球墨铸铁潮湿的振动，并通过铸造制成。它有导轨，使运输方便纵向滑动。该车床的床的高度要适当，使技术人员做他或她的工作轻松，舒适。 启闭。

主轴箱固定在床身的左侧，包括主轴的轴线平行于导轨（床的滑动面）。主轴驱动，通过变速箱，这是在车头内。齿轮箱的功能是提供一个不同的主轴转速号码（一般为6到18的速度）。一些现代的车床主轴无级变速有速度，雇用摩擦，电气，液压驱动或headstocks。

主轴始终是空心的，一大肠杆菌，它已通过纵向延伸洞。酒吧股票可以通过该孔如果美联储连续生产的通过。另外，那个洞有一个圆锥表面，使安装一个普通车床的中心。主轴外表面有螺纹，可让卡盘，一个面盘，或类似的安装。 尾座。

尾座大会基本上由三部分组成，其基数较低，中间的一部分，羽毛笔。较低的基数为铸造，可以幻灯片上沿导轨床身，而且它的夹紧装置，以便在任何需要的位置锁定整个尾座，根据工件的长短而定。中间部分是一个可移动横，以便在与车头车尾的轴对齐的铸造。第三部分，羽毛，是一种坚硬的钢管，可以纵向移动并根据需要出中间的一部分。这是通过一个手轮和螺丝钉，围绕着它固定在套筒螺母从事使用。在开放的羽毛边孔是锥形，使车床中心或类似麻花钻镗杆或其他工具的安装。鹅毛笔可锁定在任何道路沿线的旅游点通过一个夹紧装置的手段。 马车。

马车的主要功能是安装的切削工具，产生纵向和/或跨饲料。它实际上是一个H形块，在车头和车尾之间的车床床身滑动而受到V型导轨，床型为指导。马车可以移动手动或机械由停机坪，要么饲料杆或丝杆手段。

螺纹切削时，电源提供给停机坪变速箱由丝杆。在所有其他车削操作，它是饲料棒驱动车。丝杆螺母通过半，这是固定在一定的驱动后轮对去杠杆apron.When，半坚果钳制在一起，并参与到作为一个单一的丝杠螺母旋转，这是美联储，连同与马车，沿着床。当杠杆脱开，半坚果被释放了，马车stops.On另一方面，当进料杆使用，它提供通过蜗轮权力到停机坪。后者是挂钩的饲料杆和沿饲料棒，它有一个键槽延伸至涵盖其整个length.A现代车床通常有一个快速更换变速箱

位于下启闭，并通过从主轴驱动停机坪旅行火车的齿轮。它是连接这两个饲料杆和丝杆，使饲料选择，只需适当的杠杆移动方便，迅速等。在快速变化的变速箱是采用纯车削，线切割面对和行动。由于该变速箱是联系在一起的主轴，停机坪的距离（和cuttingtool）每次主轴旅行是可以控制的，是被称为饲料。

车床切削工具

的形状和车刀几何取决于他们的目的，是employed.Turning工具可分为两大类，即外部和内部的刀具切削工具分类。这两个组别，分别包括以下类型的工具： 车削工具。

车刀可以是整理或粗车刀。粗车刀有小鼻子半径和受聘时作出大量削减。另一方面，整理工具有更大的鼻子半径，并获得通过使轻微切深度，具有良好的表面光洁度最终所需的尺寸使用。粗车工具可以右手或左手的类型，这取决于饲料的方向。他们可以有直，弯曲，或抵销柄。 面对工具。

面对工具受聘于加工平面面临侧面或端面的操作。有加工左手侧表面，为右手边面工具的工具。产生这些侧面通过饲料的交叉使用，违反了车削，在那里通常的纵向进给用。 截止工具。

截止工具，有时也称为分型工具，服务分开成几部分和/或机器外部环形沟槽工件。

螺纹切削工具。

螺纹切削工具要么三角形，方形或梯形切割边缘，而在该线截面所需而定。此外，这些工具中，飞机的角度必须始终是相同的线程的形式的。螺纹切削工具有外螺纹切削直柄和弯柄型切割时的内部线程。 表格工具。

表格工具，特别是生产采取一定的形式，这是对面的高速钢刀具的加工

workpiece.An所需的形状通常是在一个单件的形式提出的边缘，违背硬质合金或陶瓷，这是在做形式的提示。后者是焊接或机械固定在钢shanks.Fig.11.2表明后者的一个类型，其中包括硬质合金尖，断屑，垫，夹紧螺钉（带洗衣机和一个螺母）的安排，小腿。顾名思义，该芯片的断路器功能就是要打破长期芯片每一个现在，然后，从而防止了很长的彩带形成扭曲可能导致加工过程中出现的问题。在硬质合金（或陶瓷提示）可以有不同的形状，经加工操作的，他们是被雇用而定。的提示可以是固体或通孔与，取决于钎焊或机械夹紧用于安装在柄端就业。 车床操作

在下面的部分，我们讨论各种机械加工，可在一个传统的发动机lathe.It进行的操作，必须牢记，但是，现代的电脑数控车床有更多的功能，可以做其他操作，如轮廓，因为，例子。以下是普通车床的操作。 圆柱转动。

圆柱转动是最简单，最常见的车床操作。一个单一的工件整圈产生一个圆，圆心轴的车床汪洋大海;这项议案，然后复制作为工具的轴向进给运动的结果无数次。由此产生的加工痕迹，因此，有一个螺旋间隔非常小，这等于饲料。因此，总是

可以手动或自动，cylindrical.The加工表面轴向进给所提供的运输或其他化合物，

而切削深度由粗加工削减slide.In交叉控制的，所以建议在大深度削减（高达0.25

英寸或6mm，根据工件材料而定），将使用更小的饲料。另一方面，非常好的饲料，较小的切削深度（小于0.05in，或0.4毫米），高切削速度优先用于精加工的削减。 面对的问题。

面临的一个操作的结果是一个平面的表面，或者是在一个环形工件或像一整面肩端面的中间。在一个面临经营，饲料所提供的十字，而切削深度是由运输或其他复合控制。面对可以进行无论是从外围向内或从工件中心向外。很明显，在这两种情况下，加工痕迹采取一个螺旋形状。 通常，这是首选打击行动的过程中面临的运输，由于切削力现象，可以把工具（而且，当然，整个车厢）远离工件。在大多数面临操作，工件保持在卡盘上或面板。 沟槽切削加工。

在停产和凹槽切割操作，只有横向进给的工具是就业。在切断和切槽工具，这是前面所讨论的，是就业。 镗内孔。

镗内孔的内表面上执行了一个无聊的酒吧或合适的内部切割工具。如果最初的工件是固体，钻井作业，必须首先执行。钻井工具尾座举行，后者则是美联储对工件。

锥转向。

锥转向是通过推动一个方向不平行，而是倾斜的车床轴与某个角度等于所需的锥角给它的工具。以下是锥形转向实际应用的不同方法：

（1）旋转的角度等于用一半的锥顶角复合休息光盘。饲料是手动起动手柄提供其余的化合物。建议使用此方法对外部和内部表面车削圆锥锥角时，是比较大的。 （2）雇用外部，很短，锥面的特殊形式的工具。工件的宽度必须略低于工具，小，工件一般在每年的卡盘或一张脸板夹紧。在这种情况下，只有交叉饲料加工过程中使用过程和运输是夹在机床。

）长 （3）抵销尾座中心。这种方法是采用外部锥所需要的有小锥角（小于8 °

工件转动。工件安装在两个中心之间，然后尾座中心转移的方向垂直于车床轴的距离S。

（4）用锥形车削附件。此方法用于工件的车削很长，当长度大于其余的复合全行程较大。在这种情况下所遵循的程序涉及到从马车十字，然后由该锥形车削附件引导完全脱离接触。

在这个过程中，自动轴向进给可照常使用。此方法建议用小锥角，例如，8到

很长的工件。 10 ° °

螺纹切削。

当执行丝线切割，轴向进给必须保持在一个恒定的速率，这是建立在对工件转速（RPM）的依赖。两者间的关系，是由该线程的音调，主要是前面提到的cut.As，轴向进给切削时自动生成由丝杆，驱动马车意味着线程。当丝杠旋转一次，马车旅行的距离等于丝杆螺距。因此，如果丝杆转速等于该主轴（即，即工件），对由此导致的螺距是完全相同的铅螺钉。由此产生的螺距被切断，因此总是取决于对丝杠的转动速度比和主轴：

螺距丝杠/工件的音调或等于工件转/丝杆=主轴到运输负债比率转。

这个方程在确定之间的车床主轴和丝杠动态联动有用并能培养他们之间的齿轮正确选择。

在切割作业线，工件可以是举行的卡盘或两者之间的相对长工件车床为中心

展开。所使用的必须完全配合的螺纹轮廓工具的形式被削减，即三角工具必须使用三角螺纹等。 滚花。

滚花的形成主要是行动中没有芯片的生产。它涉及对旋转工件按两个粗糙的表面硬化辊类文件造成的工件金属塑性变形。

滚花进行了以生产粗，圆柱（或圆锥）表面，通常用作手柄。有时候，表面滚花，只是为了装饰缘故，社会上有滚花图案可从中选择不同的类型。 切削速度和进给

切割速度快，通常是每分钟表面英尺（SFM）的给予，是在圆周方向行驶的一对工件表面在1分钟内（即切）给定点的脚数。 表面之间的速度和转速的关系可以由下列公式： 可持续森林管理=πDN 凡

ð =工件的直径在脚下 每组的rpm

表面切割速度主要依赖于被加工的材料，以及作为切削刀具材料和可从手册中，刀具制造商提供的信息，等等。一般来说，可持续森林管理作为100当加工冷轧或低碳钢，较软的材料。50时更严厉的金属加工和机械加工为200时，

铝，通常采取的可持续森林管理是400或以上。另外，还有一些影响面切割速度的最优值的其他变量。这些工具包括几何，润滑剂或冷却剂，饲料类型和切削深度。只要切割速度决定的，转速的主轴（转）可以计算如下： 每组可持续森林管理/（πD）

一个合适的饲料的选择取决于许多因素，如要求的表面光洁度，切削深度，所用刀具几何形状。更精细的饲料生产出更好的表面光洁度，而高饲料加工时间缩短在该工具与workpiece.Therefore直接接触，所以一般建议使用饲料，粗加工和精加工操作更精细的饲料高。同样，推荐值饲料，可作为指导方针采取在资料手册和刀具制造商提供的小册子找到。