数控车床主轴部件机械课程毕业设计外文文献翻译@中英文翻译@外文翻译

中国地质大学长城学院 本科毕业 设计 外文资料翻译 系 别： 工程技术系 专 业： 机械设计制造及其自动化 姓 名： 王泽民 学 号： 05211636 2015 年 4 月 30 日 1 外文原文 翻译 数控车床主轴部件 车床是主要用于生成旋转表面和平整边缘的机床。根据它们的使用目的、结构、能同时被安装刀具的数量和自动化的程度，车床 更确切地说是车床类的机床， 可以被分成以下几类： (1)普通车床 (2)万能车床 (3)转塔车床 (4)立式车床 (5)自动车床 (6)特殊车床 虽然车床类的机床多种多样，但它们在结构和操作原理上具有共同特性。这些特性可以通过普通车床这一最常用的代表性类型来最好地说明。下面是关于图 11.1所示普通车床的主要部分的描述。 车床床身：车床床身是包含了在两个垂直支柱上水平横梁的主骨架。为减振它一般由灰铸铁或球墨铸铁铸造而成。 它上面有能让大拖板轻易纵向滑动的导轨。车床床身的高度应适当以让技师容易而舒适地工作。 主轴箱：主轴箱固定在车床床身的 左侧，它包括轴线平行于导轨的主轴。主轴通过装在主轴箱内的齿轮箱驱动。 齿轮箱的功能是给主轴提供若干不同的速度 (通常是 6到 18速 )。有些现代车床具有采用摩擦、电力或液压驱动的无级调速主轴箱。主轴往往是中空的，即纵向有一通孔。如果采取连续生产，棒料能通过此孔进给。同时，此孔为锥形表面可以安装普通车床顶尖。主轴外表面是螺纹可以安装卡盘、花盘或类似的装置。 尾架：尾架总成基本包括三部分，底座、尾架体和套筒轴。底座是能在车床床身上沿导轨滑动的铸件，它有一定位装置能让整个尾架根据工件长度锁定在任何需要位置。 这通 过使用手轮和螺杆来达到，与螺杆啮合的是一固接在套筒轴上的螺母。套筒轴开口端的孔是锥形的，能安装车床顶尖或诸如麻花钻和镗杆之类的工具。套筒轴通过定位装置能沿着它的移动路径被锁定在任何点。 大拖板：大拖板的主要功能是安装刀具和产生纵向和 /或横向进给。它实际上是一由车床床身 V形导轨引导的、能在车床床身主轴箱和尾架之间滑动的 H 形滑块。 大拖板能手动或者通过溜板箱和光杆 (进给杆 )或丝杆 (引导螺杆 )机动。 在切削螺旋时，动力通过丝杆提供给溜板箱上的齿轮箱。在其余车削作业中，都由光杆驱动大拖板。丝杆穿过一对固定 在溜板箱后部的剖分螺母。当开动特定操作杆时，剖分螺母夹在一起作为单个螺母与旋转的丝杆啮合，并带动拖板沿着床身提供进给。当操作杆脱离时，剖分螺母释放同时大拖板停止运动。 另一方面，当使用光杆时则通过蜗轮给溜板箱提供动力。 蜗轮用键连接在光杆上，并与溜板箱一起沿光杆运动，光杆全长范围开有键槽。 现代车床一般在主轴箱下装备快速变换齿轮箱，通过一系列齿轮由主轴驱动。它与光杆和丝杆连接，能容易并快速地通过简单转换适当的操作杆选择各种进给。 2 快速变换齿轮箱可用于普通车削、端面切削和螺旋切削作业中。由于这种齿轮箱与主轴相连，主轴每转一圈溜板箱 (和切削刀具 )运动的距离能被控制，这距离就可以被认为是进给。 车床刀具的形状和几何参数取决于它们的使用目的。 车削刀具可以分为两个主要组别，即外部切削刀具和内部切削刀具。这两组中的每一组都包括以下类型刀具：车削刀具：车削刀具可以是精车刀具或粗车刀具。粗车刀具刀尖半径较小，用于深切削。 而精车刀具刀尖半径较大，用于通过微量进刀深度来获得具有较好表面光洁度的最终所需尺寸。粗车刀具按其进给方向可以是右手型的或是左手型的。它们可以有直的、弯的或偏置的刀杆。 端面刀具：端面刀具用在端 面作业中加工平板侧面或端部表面，也有加工左右侧表面之分。与一般采用纵向进给的车削作业相反，那些侧表面通过采用横向进给产生。 切断刀具：切断刀具，有时也称为分割刀具，用于将工件分割成若干部分和 /或加工外部环形槽。 螺纹切削刀具：螺纹切削刀具根据所需螺纹的横截面，有三角形的、矩形的或梯形的切削刃。同时，这些刀具的平面角必须始终与螺纹形状的平面角保持一致。 车外螺纹的螺纹切削刀具为直刀杆，而车内螺纹的螺纹切削刀具则是弯刀杆。 成形刀具：成形刀具有专门制成特定形状的刀刃，这种刀刃形状与被加工工件所需外形 正好相反。 高速钢刀具通常以单件形式制造，而硬质合金或陶瓷刀具则以刀尖形式制造。后者用铜焊或机械方法固定于钢质刀杆上。 顾名思义，断屑槽的功能就是不时地折断长切屑，以防形成很长的可能会在机加工操作中引起问题的缠绕切屑条。 硬质合金刀尖 (或陶瓷刀尖 )根据采用它们的机加工操作，可以有不同的形状。根据将刀尖装配在刀杆上是通过用铜焊还是机械卡装，刀尖可以是实心的或是带有中心通孔的。 在下面这节中，要讨论的是能在传统普通车床上进行的各种机加工作业。然而，必须记住现代计算机数控车床具有更多的功能并且可以进行其 它操作，例如仿型。下面是传统车床的操作。 圆柱面车削：圆柱面车削是所有车床操作中最简单也是最普通的。工件旋转一整圈产生一个圆心落在车床主轴上的圆；由于刀具的轴向进给运动这种动作重复许多次。 所以，由此产生的机加工痕迹是一条具有很小节距的螺旋线，该节距等于进给。因此机加工表面始终是圆柱形的。 轴向进给通过大拖板或复式刀架手动或自动提供，然而切削深度则由横向滑板控制。 粗车中，推荐使用较大切削深度 (根据工件材料可达 0.25英寸或 6 毫米 )和较小进给。另一方面，精车则最好采用很小的进给、较小的切削深度 (小于 0.05 英寸或 0.4毫米 )和较高的切削速度。 端面车削：端面车削操作的结果是将工件整个端部表面或者像轴肩之类的中间环形表面加工平整。在端面车削操作中，进给由横向滑板提供，而切 3 削深度则通过大拖板或复式刀架控制。端面车削既可以从外表面向内切削也可以从工件中心往外切削。很明显在这两种情况下机加工痕迹都是螺线形式。 通常在端面车削作业时习惯于采用夹住大拖板，这是因为切削力倾向于将刀具 (当然包括整个大拖板 )推离工件。在大多数端面车削作业中，工件被支撑在卡盘或花盘上。 开槽：在切断和开槽操作中，刀具只有横向进给。要 采用前面已经讨论过的切断和开槽刀具。 镗孔和内部车削：镗孔和内部车削通过镗杆或合适的内部切削刀具在内表面进行。如果初始工件是实心的，则必须首先进行钻孔作业。钻孔刀具安装在尾架上，然后对着工件进给。 锥面车削：锥面车削通过沿着与车床主轴不平行而倾斜成一个等于锥面所需角度的方向进刀来实现。下面是在实际锥面车削中采用的不同方法： (1) 将复式刀架盘旋转一个等于圆锥体顶角一半的角度。通过摇动复式刀架操纵柄手动提供进给。当锥角相对较大时切削外锥面和内锥面推荐使用这种方法。 (2) 对很短的外锥面采用特殊的成 型刀具。工件的宽度必须略小于刀具的宽度，并且工件通常由卡盘支撑或夹紧在花盘上。在这种情况下，机加工作业时只有横向进给而大拖板则夹紧在床身上。 (3)偏移尾架顶尖。对需要较小锥角 (小于 8 ) 的较长工件外锥面车削采用这种方法。工件安装于两顶尖之间；然后将尾架顶尖朝垂直于车床主轴方向移动一距离 S。 (4) 采用锥面车削附加装置。这种方法用于车削很长的工件，其长度大于复式刀架的整个行程。在这种场合下要遵循的步骤是将横向滑板完全脱离大拖板，然后通过锥面车削附加装置进行引导。 在此作业中，能照常使用自动轴向进给 。对具有较小锥角 (即 8到 10 )的很长工件推荐采用这种方法。 螺纹切削：在螺纹切削作业时，轴向进给必须保持恒定速率，这取决于工件的转速(rpm)。两者之间的关系基本上由被切削螺纹所需的节距决定。 如前所述，当依靠驱动大拖板的丝杆切削螺纹时轴向进给是自动产生的。丝杆旋转一圈，大拖板就行进等于丝杆节距的一段距离。 因此如果丝杆的旋转速度等于心轴的转速 (即工件的转速 )，生成切削螺纹的节距就正好等于丝杆的节距。 所以被切削生成螺纹的节距总是取决于丝杆和心轴的转速比：丝杆的节距 /工件所需节距 =工件转速 /丝杆 转速 =心轴到大拖板的传动比。 这公式在决定车床心轴和丝杆之间的运动学关系时很有用，并且提供了正确挑选它们之间轮系的方法。 在螺纹切削作业中，工件既能支撑于卡盘中，对相对较长的工件也能安装在两个车床顶尖之间。使用的刀具外形必须正好与要切削螺纹的轮廓一致，即三角形刀具必须用于三角形螺纹等等。 4 外文原文 Numerical Control Lathe Spindle An HSS tool is usually made in the form of a single piece, contrary to cemented carbidesor ceramic, which are made in the form of tips. The latter are brazed or mechanically fastenedto steel shanks 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.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 f 5 orce 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., 8through 10. Thread cutting. When performing thread cutting, the axial feed must be kept at a constantrate, 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 threadby means of the lead screw, which drives the carriage. When the lead screw rotates a single revolution, the carriage travels a distance equ