外文翻译-车床和车削
英文材料
Lathe and Turning
The Lathe and Its Construction
A lathe is a machine tool used primarily for producing surfaces of revolution 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 follow s:
(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 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 supporis. 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 jib 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 silde 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 througth that hole if continous production is adopted . A lso , 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 .
Tallstock . 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 guidewayes , 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 parte is a casting that can be moved transversely to enable alignment of the axis of the 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 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 o 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 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 wrom gear . The latter is keyed to 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 spindle, the distance that the apron (and the cutting tool) 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 tow main groups,namely,external cutting tools and internal cutting tools , Each of these groups include the following types of tools:
Turning tools. Turing tools can be either finishing or rough turning tools . Rough turning tools have small nose radii and are used for obtaining the final required dimensions with good surface finish by marking slight depth 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 annual grooves.
Thread-cutting tools. Thread-cutting tools have either triangular, square, or tranpezoidal 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 tools is usually made in the form of a single piece ,contrary to cemented carbides or ceramic , which are made in the form of tipes. 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 operations . 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 capabiblities and do other operations ,such as contouring , for example . Following are conventional lathe operations.
Cylindrical turning . Cylindrical turning is the the simplest and the most common of
all lathe operations . A single full turn of the workpiece generate 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 depths of cuts is controlled by the cross slide . In roughing cuts , it is recommended that large depths of cuts (up to 0.25 in. or 6 mm, depending upon the workpiece material) and smaller feeds would be used. On the other hand , very fine feeds, smaller depth of cut (less than 0.05in. , or 0.4 mm) , 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 in ward or from the center of the workpiece outward . It is obvious that the machining marks in both cases tack 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 are performed on the internal surfaces by a boring bar or suitable internal workpiece is solid, a drilling operation must be performed first . The drilling tool is held in the tailstock, and latter is then fed against the workpiece.
Taper turning . Taper turning is achieved by driving the tool in a direction that is not paralled 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: Rotating the disc of the compound rest with an angle 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.
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 . I n this case , only the cross feed is used during the machining process and the carriage is clamped to the machine bed .
Offsetting the tailstock center . This method is employed for esternal tamper turning of long workpiece that are required to have small tamper 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.
Using the taper-turning attachment . This method is used for turning very long workpoece , 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 recommend for very long workpiece 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 rotates a single revolutional 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 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 scew and the spindle :
Pitch of the lead screw rpm of the workpiece = spindle-to-carriage gearing ratio Desired pitch of workpiece rpm of lead screw
This equation is usefully in determining the kinematic linkage between the lathe spindle and the lead screw and enables proper selection of the gear train between them .
n thread cutting operations , the workpiece can either be held in the chuck or mounted between the two lathe centers for relatively long workpiece . The form of the tool used must exactly coincide with the profile 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 prodyced . Tt involves pressing two hardened rolls with rough filelike surfaces against the rotating
机械毕业设计英文外文翻译71车床夹具设计分析
附录A Lathe fixture design and analysis Ma Feiyue (School of Mechanical Engineering, Hefei, Anhui Hefei 230022, China) Abstract: From the start the main types of lathe fixture, fixture on the flower disc and angle iron clamp lathe was introduced, and on the basis of analysis of a lathe fixture design points. Keywords: lathe fixture; design; points Lathe for machining parts on the rotating surface, such as the outer cylinder, inner cylinder and so on. Parts in the processing, the fixture can be installed in the lathe with rotary machine with main primary uranium movement. However, in order to expand the use of lathe, the work piece can also be installed in the lathe of the pallet, tool mounted on the spindle. THE MAIN TYPES OF LATHE FIXTURE Installed on the lathe spindle on the lathe fixture
机械毕业设计英文外文翻译608组合机床CAD系统开发与研究
外文资料 The aggregate machine-tool CAD system development and research Abstract aggregate machine-tool CAD is in Window 95/98, Wndows under the NT4.0 environment, designs personnel's special-purpose CAD system with VC5.0 and the AutoCAD R14 ADS/ARX technology development face the aggregate machine-tool.This software technological advance, performance reliable, function strong, convenient practical, has provided the modernized design tool for our country aggregate machine-tool profession. Key word: Aggregate machine-tool CAD jig CAD multi-axle-box CAD 1 uses the aggregate machine-tool CAD technology imperative The aggregate machine-tool is with according to serialized, the standardized design general part and the special purpose machine which composes according to the work piece shape and the processing technological requirement design special-purpose part, belongs to the disposable design, the disposable manufacture piecework product.Therefore, the design quantity is big, the design work is complex.In the
机械类数控车床外文翻译外文文献英文文献车床.doc
Lathes Lathes are machine tools designed primarily to do turning, facing and boring, Very little turning is done on other types of machine tools, and none can do it with equal facility. Because lathes also can do drilling and reaming, their versatility permits several operations to be done with a single setup of the work piece. Consequently, more lathes of various types are used in manufacturing than any other machine tool. The essential components of a lathe are the bed, headstock assembly, tailstock assembly, and the leads crew and feed rod. The bed is the backbone of a lathe. It usually is made of well normalized or aged gray or nodular cast iron and provides s heavy, rigid frame on which all the other basic components are mounted. Two sets of parallel, longitudinal ways, inner and outer, are 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 way in one or both sets, They are precision-machined to assure accuracy of alignment. On most modern lathes the way are surface-hardened to resist wear and abrasion, but 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 headstock is mounted in a foxed position on the inner ways, usually at the left end of the bed. It provides a powered means of rotating the word at various speeds . Essentially, it consists of a hollow spindle, mounted in accurate bearings, and a set of transmission gears-similar to a truck transmission—through which the spindle can be rotated at a number of speeds. Most lathes provide from 8 to 18 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. The spindle has a hole extending through its length, through which long bar stock can be fed. The size of maximum size of bar stock that can be machined when the material must be fed through spindle. The tailsticd 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, to permit aligning the assembly is the tailstock quill. This is a hollow steel cylinder, usually about 51 to 76mm(2to 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 size of a lathe is designated by two dimensions. The first is known as the swing. This is the maximum diameter of work that can be rotated on a lathe. It is approximately twice the distance between the line connecting the lathe centers and the nearest point on the ways, The second size dimension is the maximum distance between centers. The swing thus indicates the maximum work piece diameter that can be turned in the lathe, while the distance between centers indicates the maximum length of work piece that can be mounted between centers. Engine lathes are the type most frequently used in manufacturing. They are heavy-duty machine tools with all the components described previously and have power drive for all tool movements except on the compound rest. They commonly range in size from 305 to 610 mm(12 to 24 inches)swing and from 610 to 1219 mm(24 to 48 inches) center distances, but swings up to 1270 mm(50 inches) and center distances up
机械设计外文翻译-- 机械加工介绍
毕业论文（设计） 外文翻译 题目：机械加工介绍
机械加工介绍 1.车床 车床主要是为了进行车外圆、车端面和镗孔等项工作而设计的机床。车削很少在其他种类的机床上进行，而且任何一种其他机床都不能像车床那样方便地进行车削加工。由于车床还可以用来钻孔和铰孔，车床的多功能性可以使工件在一次安装中完成几种加工。因此，在生产中使用的各种车床比任何其他种类的机床都多。 车床的基本部件有：床身、主轴箱组件、尾座组件、溜板组件、丝杠和光杠。 床身是车床的基础件。它能常是由经过充分正火或时效处理的灰铸铁或者球墨铁制成。它是一个坚固的刚性框架，所有其他基本部件都安装在床身上。通常在床身上有内外两组平行的导轨。有些制造厂对全部四条导轨都采用导轨尖朝上的三角形导轨（即山形导轨），而有的制造厂则在一组中或者两组中都采用一个三角形导轨和一个矩形导轨。导轨要经过精密加工以保证其直线度精度。为了抵抗磨损和擦伤，大多数现代机床的导轨是经过表面淬硬的，但是在操作时还应该小心，以避免损伤导轨。导轨上的任何误差，常常意味着整个机床的精度遭到破坏。 主轴箱安装在内侧导轨的固定位置上，一般在床身的左端。它提供动力，并可使工件在各种速度下回转。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8~12种转速，一般按等比级数排列。而且在现代机床上只需扳动2~4个手柄，就能得到全部转速。一种正在不断增长的趋势是通过电气的或者机械的装置进行无级变速。 由于机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，通常安装在预紧后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，因此当工件必须通过主轴孔供料时，它确定了能够加工的棒料毛坯的最大尺寸。 尾座组件主要由三部分组成。底板与床身的内侧导轨配合，并可以在导轨上作纵向移动。底板上有一个可以使整个尾座组件夹紧在任意位置上的装置。尾座体安装在底板上，可以沿某种类型的键槽在底板上横向移动，使尾座能与主轴箱中的主轴对正。尾座的第三个组成部分是尾座套筒。它是一个直径通常大约在51~76mm之间的钢制空心圆柱体。
组合机床毕业设计外文翻译
The Aggregate Machine-tool The Aggregate Machine-tool is based on the workpiece needs, based on a large number of common components, combined with a semi-automatic or automatic machine with a small number of dedicated special components and process according to the workpiece shape and design of special parts and fixtures, composed. Combination machine is generally a combination of the base, slide, fixture, power boxes, multi-axle, tools, etc. From. Combination machine has the following advantages: (1) is mainly used for prism parts and other miscellaneous pieces of perforated surface processing. (2) high productivity. Because the process of concentration, can be multi-faceted, multi-site, multi-axis, multi-tool simultaneous machining. (3) precision and stability. Because the process is fixed, the choice of a mature generic parts, precision fixtures and automatic working cycle to ensure consistent processing accuracy. (4) the development cycle is short, easy to design, manufacture and maintenance, and low cost. Because GM, serialization, high degree of standardization, common parts can be pre-manufactured or mass organizations outsourcing. (5) a high degree of automation, low labor intensity. (6) flexible configuration. Because the structure is a cross-piece, combination. In accordance with the workpiece or process requirements, with plenty of common parts and a few special components consisting of various types of flexible combination of machine tools and automatic lines; tools to facilitate modification: the product or process changes, the general also common components can be reused. Combination of box-type drilling generally used for processing or special shape parts. During machining, the workpiece is generally not rotate, the rotational motion of the tool relative to the workpiece and tool feed movement to achieve drilling, reaming, countersinking, reaming, boring and other processing. Some combination of turning head clamp the workpiece using the machine to make the rotation, the tool for the feed motion, but also on some of the rotating parts (such as the flywheel, the automobile axle shaft, etc.) of cylindrical and face processing. Generally use a combination of multi-axis machine tools, multi-tool, multi-process, multi-faceted or multi-station machining methods simultaneously, productivity increased many times more than generic tools. Since the common components have been standardized and serialized, so can be flexibly configured according to need, you can shorten the design and manufacturing cycle. Multi-axle combination is the core components of general machine tools. It is the choice of generic parts, is designed according to special requirements, in combination machine design process, is one component of a larger workload. It is based on the number and location of the machining process diagram and schematic design combination machine workpiece determined by the hole, cutting the amount of power transmission components and the design of each spindle spindle type movement. Multi-axle power from a common power box, together with the power box installed on the feed slide, to be completed by drilling, reaming and other machining processes. The parts to be processed according to the size of multi-axle box combination machine tool design, based on an original drawing multi-axle diagram, determine the range of design data,
【机械类文献翻译】机床
毕业设计(论文)外文资料翻译 系部： 专业： 姓名： 学号： 外文出处：English For Electromechanical (用外文写) Engineering 附件：1.外文资料翻译译文；2.外文原文。 指导教师评语： 此翻译文章简单介绍了各机床的加工原理，并详细介绍了各机床的构造，并对方各机床的加工方法法进行了详细的描述， 翻译用词比较准确，文笔也较为通顺，为在以后工作中接触英 文资料打下了基础。 签名： 年月日注：请将该封面与附件装订成册。
附件1：外文资料翻译译文 机床 机床是用于切削金属的机器。工业上使用的机床要数车床、钻床和铣床最为重要。其它类型的金属切削机床在金属切削加工方面不及这三种机床应用广泛。 车床通常被称为所有类型机床的始祖。为了进行车削，当工件旋转经过刀具时，车床用一把单刃刀具切除金属。用车削可以加工各种圆柱型的工件，如：轴、齿轮坯、皮带轮和丝杠轴。镗削加工可以用来扩大和精加工定位精度很高的孔。 钻削是由旋转的钻头完成的。大多数金属的钻削由麻花钻来完成。用来进行钻削加工的机床称为钻床。铰孔和攻螺纹也归类为钻削过程。铰孔是从已经钻好的孔上再切除少量的金属。 攻螺纹是在内孔上加工出螺纹，以使螺钉或螺栓旋进孔内。 铣削由旋转的、多切削刃的铣刀来完成。铣刀有多种类型和尺寸。有些铣刀只有两个切削刃，而有些则有多达三十或更多的切削刃。铣刀根据使用的刀具不同能加工平面、斜面、沟槽、齿轮轮齿和其它外形轮廓。 牛头刨床和龙门刨床用单刃刀具来加工平面。用牛头刨床进行加工时，刀具在机床上往复运动，而工件朝向刀具自动进给。在用龙门刨床进行加工时，工件安装在工作台上，工作台往复经过刀具而切除金属。工作台每完成一个行程刀具自动向工件进给一个小的进给量。 磨削利用磨粒来完成切削工作。根据加工要求，磨削可分为精密磨削和非精密磨削。精密磨削用于公差小和非常光洁的表面，非精密磨削用于在精度要求不高的地方切除多余的金属。 车床 车床是用来从圆形工件表面切除金属的机床，工件安装在车床的两个顶尖之间，并绕顶尖轴线旋转。车削工件时，车刀沿着工件的旋转轴线平行移动或与工件的旋转轴线成一斜角移动，将工件表面的金属切除。车刀的这种位移称为进给。车
组合机床外文文献
Int J Adv Manuf Technol (2006) 29: 178–183 DOI 10.1007/s00170-004-2493-9
ORIGINAL ARTICLE
Ferda C. C ? etinkaya
Unit sized transfer batch scheduling in an automated two-machine ?ow-line cell with one transport agent
Received: 26 July 2004 / Accepted: 22 November 2004 / Published online: 16 November 2005 ? Springer-Verlag London Limited 2005 Abstract The process of splitting a job lot comprised of several identical units into transfer batches (some portion of the lot), and permitting the transfer of processed transfer batches to downstream machines, allows the operations of a job lot to be overlapped. The essence of this idea is to increase the movement of work in the manufacturing environment. In this paper, the scheduling of multiple job lots with unit sized transfer batches is studied for a two-machine ?ow-line cell in which a single transport agent picks a completed unit from the ?rst machine, delivers it to the second machine, and returns to the ?rst machine. A completed unit on the ?rst machine blocks the machine if the transport agent is in transit. We examine this problem for both unit dependent and independent setups on each machine, and propose an optimal solution procedure similar to Johnson’s rule for solving the basic two-machine ?owshop scheduling problem. Keywords Automated guided vehicle · Lot streaming · Scheduling · Sequencing · Transfer batches entire lot to ?nish its processing on the current machine, while downstream machines may be idle. It should be obvious that processing the entire lot as a single object can lead to large workin-process inventories between the machines, and to an increase in the maximum completion time (makespan), which is the total elapsed time to complete the processing of all job lots. However, the splitting of an entire lot into transfer batches to be moved to downstream machines permits the overlapping of different operations on the same product while work proceeds, to complete the lot on the upstream machine. There are many ways to split a lot: transfer batches may be equal or unequal, with the number of splits ranging from one to the number of units in the job lot. For instance, consider a job lot consisting of 100 identical items to be processed in a three-stage manufacturing environment in which the ?ow of its operations is unidirectional from stage 1 through stage 3. Assume that the unit processing time at stages 1, 2, and 3 are 1, 3, 2 min, respectively. If we do not allow transfer batches, the throughput time is (100)(1+3+2) = 600 min (see Fig. 1a). However, if we create two equal sized transfer batches through all stages, the throughput time decreases to 450 min, a reduction of 25% (see Fig. 1b). It is clear that the throughput time decreases as the number of transfer batches increases. Flowshop problems have been studied extensively and reported in the literature without explicitly considering transfer batches. Johnson [1], in his pioneering work, proposed a polynomial time algorithm for determining the optimal makespan when several jobs are processed on a two-machine (two-stage) ?owshop with unlimited buffer. With three or more machines, the problem has been proven to be NP-hard (Garey et al. [2]). Besides the extension of this problem to the m -stage ?owshop problem, optimal solutions to some variations of the basic two-stage problem have been suggested. Mitten [3] considered arbitrary time lags, and optimal scheduling with setup times separated from processing was developed by Yoshida and Hitomi [4]. Separation of the setup, processing and removal times for each job on each machine was considered by Sule and Huang [5]. On the other hand, ?owshop scheduling problems with transfer batches have been examined by various researchers. Vickson
1 Introduction
Most classical shop scheduling models disregard the fact that products are often produced in lots, each lot (process batch) consisting of identical parts (items) to be produced. The size of a job lot (i.e., the number of items it consists of) typically ranges from a few items to several hundred. In any case, job lots are assumed to be indivisible single entities, although an entire job lot consists of many identical items. That is, partial transfer of completed items in a lot between machines on the processing routing of the job lot is impossible. But it is quite unreasonable to wait for the
F.C. ?etinkaya (u) Department of Industrial Engineering, Eastern Mediterranean University, Gazimagusa-T.R.N.C., Mersin Turkey E-mail: ferda.cetinkaya@https://www.360docs.net/doc/d35771925.html,.tr Tel.: +90-392-6301052 Fax: +90-392-3654029
机床加工外文翻译参考文献
机床加工外文翻译参考文献(文档含中英文对照即英文原文和中文翻译) 基本加工工序和切削技术 基本加工的操作 机床是从早期的埃及人的脚踏动力车和约翰·威尔金森的镗床发展而来的。它们为工件和刀具提供刚性支撑并可以精确控制它们的相对位置和相对速度。基本上讲，金属切削是指一个磨尖的锲形工具从有韧性的工件表面上去除一条很窄的金属。切屑是被废弃的产品，与其它工件相比切屑较短，但对于未切削部分的厚度有一定的增加。工件表面的几何形状取决于刀具的形状以及加工操作过程中刀具的路径。 大多数加工工序产生不同几何形状的零件。如果一个粗糙的工件在中心轴上转动并且刀具平行于旋转中心切入工件表面，一个旋转表面就产生了，这种操作称为车削。如果一个空心的管子以同样的方式在内表面加工，这种操作称为镗孔。当均匀地改变直径时便产生了一个圆锥形的外表面，这称为锥度车削。如果刀具接触点以改变半径的方式运动，那么一个外轮廓像球的工件便产生了；或者如果工件足够的短并且支撑是十分刚硬的，那么成型刀具相对于旋转轴正常进给的一个外表面便可产生，短锥形或圆柱形的表面也可形成。
平坦的表面是经常需要的，它们可以由刀具接触点相对于旋转轴的径向车削产生。在刨削时对于较大的工件更容易将刀具固定并将工件置于刀具下面。刀具可以往复地进给。成形面可以通过成型刀具加工产生。 多刃刀具也能使用。使用双刃槽钻钻深度是钻孔直径5-10倍的孔。不管是钻头旋转还是工件旋转，切削刃与工件之间的相对运动是一个重要因数。在铣削时一个带有许多切削刃的旋转刀具与工件接触，工件相对刀具慢慢运动。平的或成形面根据刀具的几何形状和进给方式可能产生。可以产生横向或纵向轴旋转并且可以在任何三个坐标方向上进给。 基本机床 机床通过从塑性材料上去除屑片来产生出具有特别几何形状和精确尺寸的零件。后者是废弃物，是由塑性材料如钢的长而不断的带状物变化而来，从处理的角度来看，那是没有用处的。很容易处理不好由铸铁产生的破裂的屑片。机床执行五种基本的去除金属的过程：车削，刨削，钻孔，铣削。所有其他的去除金属的过程都是由这五个基本程序修改而来的，举例来说，镗孔是内部车削；铰孔，攻丝和扩孔是进一步加工钻过的孔；齿轮加工是基于铣削操作的。抛光和打磨是磨削和去除磨料工序的变形。因此，只有四种基本类型的机床，使用特别可控制几何形状的切削工具1.车床，2.钻床，3.铣床，4.磨床。磨削过程形成了屑片，但磨粒的几何形状是不可控制的。 通过各种加工工序去除材料的数量和速度是巨大的，正如在大型车削加工，或者是极小的如研磨和超精密加工中只有面的高点被除掉。一台机床履行三大职能：1.它支撑工件或夹具和刀具2.它为工件和刀具提供相对运动3.在每一种情况下提供一系列的进给量和一般可达4-32种的速度选择。 加工速度和进给 速度，进给量和切削深度是经济加工的三大变量。其他的量数是攻丝和刀具材料，冷却剂和刀具的几何形状，去除金属的速度和所需要的功率依赖于这些变量。 切削深度，进给量和切削速度是任何一个金属加工工序中必须建立的机械参量。它们都影响去除金属的力，功率和速度。切削速度可以定义为在旋转一周时
机械工程及自动化精品毕业设计变速箱钻孔工位组合机床左多轴箱设计外文翻译
TRANSFER AND UNIT MACHINE While the specific intention and application for transfer and unit machine vary from one machine type to another, all forms of transfer and unit machine have common benefits. Here are but a few of the more important benefits offered by TRANSFER AND UNIT MACHINE equipment. The first benefit offered by all forms of transfer and unit machine is improved automation. The operator intervention related to producing workpieces can be reduced or eliminated. Many transfer and unit machine can run unattended during their entire machining cycle, freeing the operator to do other tasks. This gives the transfer and unit machine user several side benefits including reduced operator fatigue, fewer mistakes caused by human error, and consistent and predictable machining time for each workpiece. Since the machine will be running under program control, the skill level required of the transfer and unit machine operator (related to basic machining practice) is also reduced as compared to a machinist producing workpieces with conventional machine tools. The second major benefit of transfer and unit machine technology is consistent and accurate workpieces. Today's transfer and unit machines boast almost unbelievable accuracy and repeatability specifications. This means that once a program is verified, two, ten, or one thousand identical workpieces can be easily produced with precision and consistency. rd benefit offered by most forms of transfer and unit machine tools is flexibility. Since these machines are run from programs, running a different workpiece is almost as easy as loading a different program. Once a program has been verified and executed for one production run, it can be easily recalled the next time the workpiece is to be run. This leads to yet another benefit, fast change over. Since these machines are very easy to set up and run, and since programs can be easily loaded, they allow very short setup time. This is imperative with today's just-in-time (JIT) product requirements.