車床和車削外文文獻(xiàn)翻譯@機(jī)床類中英文翻譯@外文翻譯

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 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 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 2 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: 3 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 4 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 5 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 6 workpiece to cause plastic deformation of the workpiece metal. Knurling is carried out to produce rough , cylindrical ( or concile )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 Feeds The cutting speed , which is usually given in surface feet per minute (SFM), is the number of feet traveled in circumferential direction by a given point on the surface (being cut ) of the workpiece in one minute . The relationship between the surface speed and rpm can be given by the following equation : SMF =3.14*DN Where D= the diameter of the workpiece in feet N=the rpm The surface cutting speed is dependent primarily upon the machined as well as the material of the cutting and can be obtained from handbooks , information provided by cutting tool manufacturera , 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 sofer materials . For aluminum ,the SFMis 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 sped is decided upon , the rotational speed (rpm) of the spindle can be obtained as follows : SFM =3.14*D 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, recommend values for feeds , which can be taken as guidelines , are found in handbooks and information booklets provided by cutting tool manufacturers. Here I want to introduce the drilling and milling : Drilling involves producing through or blind holes in a workpiece by forcing a tool , which rotates around its axis , against the workpiece .Consequently , the range of cutting from that axis of rotation is equal to the radius of the required hole .In practice , two symmetrical 7 cutting edges that rotate about the same axis are employed . Drilling operations can be carried out by using either hand drills or drilling machines . The latter differ in size and construction . nevertheless , the tool always rotates around its axis while the workpiece is kept firmly fixed . this is contrary to drilling on a lathe . Cutting Tool for Drilling Operations In drilling operations , a cylindrical rotary-end cutting , called a drill , is employed . The drill can have either one or more cutting edges and corresponding flutes , which can be straight or helical . the function of the flutes is to provide outlet passages for the chips generated during the drilling operation and to allow lubricants and coolants to reach the cutting edges and the surface being machined . Following is a survey of the commonly used drills. Twist drill . The twist drill is the most common type of drill .It has two cutting edges and two helical flutes that continue over the length of the drill body , as shown in Fig 12.1 The drill also consist of a neck and a shake that can be either straight or tapered .In the latter case , the shank is fitted by the wedge action into the tapered socket of the spindle and has a tang , which goes into a slot in the spindle socket ,thus acting as a solid means for transmitting rotation . On the other hand , straight shank drills are held in a drill chuck that is , in turn , fitted into the spindle socket in the same way as tapered shank drills. As can be seen in FIG.12.1 , the two cutting edges are referred to as the lips , and are connected together by a wedge , which is a chisel-like edge . The twist drill also has two margins , which enable proper guidance and locating of the drill while it is in operation . The tool point angle (TPA) is formed by the lips and is chosen based on the properties of the material to be cut . The usual TAP for commercial drills is 118 , which is appropriate for drilling low-carbon steels and cast irons . For harder and tougher metals , such as hardened steel , brasss and bronze , larger TPAs (130 OR 140 ) give better performance . The helix angle of the flutes of the commonly used twist drills ranges between 24 and 30 . When drilling copper or soft plastics , higher values for the helix angle are recommended (between 35 and 45). Twist drills are usually made of high speed steel ,although carbide tipped drills are also available . The size of twist drills used in industrial range from 0.01 up to 3.25 in . (i.e.0.25 up to 80 mm ) . Core drills . A core drill consists of the chamfer , body , neck ,and shank , as shown in Fig 12.2 . This type of drill may be have either three or four flutes and an equal number of margins , which ensure superior guidance , thus resulting in high machining accuracy . It can also be seen in Fig 12.2 that a core drill has flat end . The chamfer can have three or four cutting 8 edges or lips , and the lip angle may vary between 90 and 120 . Core drills are employed for enlarging previously made holes and not for originating holes . This type of drill is characterized by greater productivity , high machining accuracy , and superior quality of the drilled surfaces . Gun drills . Gun drills are used for drilling deep holes . All gun drills are straight fluted , and each has a single cutting edge . A hole in the body acts as a conduit to transmit coolant under considerable pressure to the tip of the drill . There are two kinds of gun drills , namely , the center cut gun drill used for drilling blind holes and the trepanning drill . The latter has a cylindrical groove at its center , thus generating a solid core , which guides the tool as it proceeds during the drilling operation. Spade drills . Spade drills are used for drilling large holes of 3.5 in .(90 mm ) or more . Their design results in a marked saving in cost of the tool as well as a tangible reduction in its weight , which facilitates its handling . moreover , this type of drill is easy to be ground . Milling and Milling Cutters Milling is a machining process that is carried out by means of a multiedge rotating tool known as a milling cutter . In this process ,metal removal is achieved through combining the rotary motion of the milling cutter and linear motions of the workpiece simultaneously . Milling operations are employed in producing flat , contoured and helical surfaces as well as for thread and gear and gear cutting operations. Each of the cutting edges of a milling cuter acts as an individual single point cutter when it engages with the workpiece metal . therefore , each of those cutting edges has the workpiece at a time ,heavy cuts can be taken without adversely affecting the tool life .In fact ,the permissible cutting speeds and feeds for milling are there to four times higher than those for turning or drilling .Moreover ,the quality of the surfaces machined by milling is generally superior of surfaces machined by turning shaping ,or drilling. A wide variety of milling cutters is available in industry .This, together with the fact that a milling machine is very versatile machine tool ,makes the milling machine the backbo ne of a machining workshop . As far as the direction of cutter rotation and workpiece feed are concerned , milling is performed by either of the following tow methods . Up milling (conventional milling). In up milling workpiece is fed against the direction of cutter rotation, as shown in Fig.12.3. As we can see in that figure ,the depth of cut (and consequently the load ) gradually increases on the successively engaged cutting edges . Therefore, the machining process involves no impact loading , thus ensuring smother operation 9 of the machine tool and longer tool life .The quality of the machined surface obtained by up milling is not very high . Nevertheless , up milling is commonly used in industry , especially for rough cuts. Down milling (climb milling ). Ascan be seen in Fig 12.3, in down milling the cutter rotation coincides with the direction of feed at the contact point between the tool and the workpiece . It can also be seen that the maximum depts. Of cut is achieved directly as the cutter engages with the workpiece . This results in a kind of impact , or sudden loading . Therefore, this method cannot be used the milling machine is equipped with a backlash elimination on the feed screw . The advantages of this method include higher quality of machined surface and easier clamping of workpieces, since the cutting forces act downward . Types of Milling Cutters There is a wide variety of milling cutter shapes .Each of them is designed to perform effectively a specific milling operations . Generally ,a milling cutter can be described as a multiedge cutting tool having the shape of a solid of revolution ,with the cutting teeth arranged either on the periphery or on an end face or on both . Following is a quick survery of the commonly used types of milling cutters. Plain milling cutter . a plain milling cutter is a disk shaped cutting tool that may have either straight or helical teeth ,as shown in Fig .12.4 .This type is always mounted on horizontal milling machines and is used for maching flat surfaces. Face milling cutter . A face milling cutter is also used for maching flat surfaces. It is bolted at the end of a short arbor ., which is in turn mounted on a vertical milling machine . Fig 12.4 indicates a milling cuter of this type. Plain metal slitting saw cutter .Fig 12.4 indicates a plain metal slitting saw cutter . We can see that it actually involves a very thin plain milling cutter. Side milling cutter. A side milling cutter is used for cutting solts, grooves, and splines. As shown in Fig 12.4 ,it is quite similar to the plain milling cutter , the difference being that this type has teeth on the sides .As is the case wih the plain cutter , the cutting teeth can be straight or helical . Angle milling cutter . Angle milling cutter is employed in cutting dovetail grooves , ratchet wheels, and the like .Fig 12.4 indicates a milling cutter of this type. T slot cutter . As shown in Fig 12.4 ,a T slot cutter involves a plain milling cutter with an integral shaft normal to it .As the name suggests ,this type is used for milling T slots. End mill cutter . End mill cutters find common applications in cutting slots , grooves , flutes , splines ,pocketing work, and the like . Fig 12.4 indicates an end mill cutter . The latter 10 is always mounted on a vertical milling machine and can have toe or four flutes , which may be either straight or helical . Form milling cutter . The teeth of a form milling cutter have a certain shape , which is identical to the section of the metal to be removed during the milling operation. Examples of this type include gear cutters ,gear hobs, convex and concave cutters ,and the like . Form milling cutters are mounted on horizontal milling machines. Materialas of Milling Cutters The commonly used milling cutters are made of high speed steel , which is generally adequate for most jobs . Milling cutters tipped with sintered carbides or cast nonferrous alloys as cutting teeth are usually employed for mass production , where heavier cuts and / or high cutting speeds are required. Here I want to introduce the Materials Types of Materials Materials may be grouped in several ways . scientists often classify materials by their state : solid , liquid , or gas . They also separate them into organic (once living) and inorganic (never living) materials. For industrial purposes , materials are divided into engineering materials or nonengineering materials .Engineering materials are those used in manufacture and become parts of products . Nonengineering materials are the chemicals ,fuels , lubricants ,and other materials used in the manufacturing process, which do not become part of the product. Engineering materials may be further subdivided into : 1 , Metals 2, Ceramics 3, Composite 4, Polymers , etc . Metals and Metals Alloys Metals are elements that generally have good electrical and thermal conductivity . Many metals have high strength , high stiffness , and have good ductility . Some metals ,such as iron ,cobalt and nickel , are magnetic . At extremely low temperatures , some metals and intermetallic compounds become superconductors. What is the difference between an alloy and a pure metal ? Pure metals are elements which come from a particular area of the periodic table . Examples of pure metals include copper in electrical wires and aluminum in cooking foil and beverage cans. Alloys contain more than one metallic element . Their properties can be changed by changing the elements present in the alloy . Examples of metal alloys include stainless steel which is an alloy of iron ,nickel ,and gold jewelry which usually contains an alloy of gold and nickel. Why are metals and alloys used ? Many metals have high densities and used in 11 applications which require a high mass to volume ratio. Some metal alloys , such as those based on aluminum , have low densities and are used in aerospace applications for fuel economy. Many alloys also have high fracture toughness, which means they can withstand impact and are durable. What are some important properties of metals? Density is defined as a material is a mass divided by its volume . Most metals have relatively high densities ,especially compared to polymers . Materials with high densities often contain atoms with high atomic numbers , such as gold or lead . However, some metals such as aluminum or magnesium have low densities ,and are used in applications that require other metallic proerties but also require low weight. Fracture toughness can be described as a materials ability to avoid fracture, especially when a flaw is introduced .Metals can generally contain nicks and dents without weakening very much ,and are impact resistant .A football player counts on this when he trusts that his facemask wont shatter. Plastic deformation is the ability of a material to bend or deform before breaking .As engineers , we usually design materials so that dont deform under normal conditions . You dont want you car to lean to the east after a strong west wind .However ,sometimes we can take advantage of plastic deformation. The crumple zones in a car absorb energy by undergoing plastic deformation before pass through. Alloy are compounds consisting of more than one metal one metal .Adding other metals can affect the density ,strength , fracture toughness , plastic deformation, electrical conductivity and environmental degradation .For example ,adding a small smount of iron to aluminum will make it stronger .Also , adding some chromium to steel will slow the rusting process, but will make it more brittle. 12 中文翻譯 車床和車削 車床和它的結(jié)構(gòu) 車床是一個主要用來生產(chǎn)旋轉(zhuǎn)表面和平面的機(jī)床 . 基于他們的目的、結(jié)構(gòu)，能同時裝夾刀具的數(shù)量 ,車床或者 , 或更正確的說 , 車床 -類型的機(jī)床依下列各項被分類為 : (1) 普通車床 (2) 萬能車床 (3) 轉(zhuǎn)塔車床 (4) 立式的車削和鉆孔機(jī)床 (5) 自動化車床 (6) 專用車床 盡管車床 -類型機(jī)床的多種多樣，他們結(jié)構(gòu)和工作的原則都有很大程度上的相似性。通過具有代表性的普通車床這些特征能最好地被說明 . 下列各項是對車床的主要元素的描述 ,如圖 .11.1. 床身 . 車床的床身是主要的框架 ,包括在二個 垂直支撐架上的水平橫梁 . 它通常由鑄鐵或者球墨鑄鐵通過鑄造加工而成的用于防止振動 . 車床上的導(dǎo)軌讓刀架容易地沿縱長滑動 . 車床床身的高度應(yīng)該適中，這樣使技術(shù)人員能夠容易地而且舒適地做他或她的操作工作。 . 主軸箱 . 主軸箱安裝在車床床身的左手邊位置而且主軸與導(dǎo)軌 (床的滑動表面 )平行 . 主軸的驅(qū)動通過齒輪箱 ,齒輪箱安裝在主軸箱中 . 齒輪箱的功能將提供一些不同的主軸轉(zhuǎn)速 (通常由 6 到 18 速度 ) . 一些現(xiàn)代的車床具有無級調(diào)速的功能 , 由磨擦力、電 , 或液壓的驅(qū)動 主軸總是中空的 , 舉個例子而言 ,它在整個 長度方向上是空的 . 如果采取連續(xù)生產(chǎn)桿狀怌料可以通過這個洞進(jìn)給 . 當(dāng)然 , 這個洞有一個錐形表面用于安裝車床頂尖 . 這個外部表面由螺紋連接吸盤，尖盤以及類似的 . 尾座 . 尾座基本上三個部份組成，下部分的基礎(chǔ)，一個中間的部份和尾部組成 . 下部份的基礎(chǔ)是沿著機(jī)床床身導(dǎo)軌上滑動的鑄件，而且它有一個定位裝置使其鎖定在整個尾座的任何需要的位置 ,根據(jù)工件的長度 . 中間部分是一個能沿著橫向移動用的鑄件 . 第三個部份套筒 , 是一個硬化處理的鋼管 , 它可以根據(jù)需要滑進(jìn)滑出中間部分 . 它可以通過手輪的使用和一個螺絲 釘，在附近固定在套筒上套筒可以被夾具鎖定在沿著行動路徑的任何點上 . 13 刀架 . 刀架的主要功能是用在刀具的安裝和縱向和橫向的進(jìn)給 . 當(dāng)被機(jī)床 V 形導(dǎo)軌引導(dǎo)的時候，它實際上是在主軸箱和尾座之間滑動的一個 H 形塊 .刀架可以用手動或機(jī)械方式通過托板箱和絲杠或光杠移動。 當(dāng)用于加工螺紋的時候 , 動力托板箱的齒輪箱提供的 . 在所有的其他車削操作方面 , 它是由光杠提供動力驅(qū)動刀架的。絲杠通過一對半螺釘固定 .這個螺釘安裝在托板箱的后面，當(dāng)操作特定的杠桿時兩個半螺釘一起被夾緊而且與旋轉(zhuǎn)的絲杠構(gòu)成一個完整的螺釘 , 當(dāng)進(jìn)給時沿床身 和刀架一起 . 當(dāng)杠桿脫離的時候，這兩個半螺釘離開并且刀架停止運動 . 另一方面，當(dāng)使用光杠的時候，它經(jīng)過蝸輪提供力量給托板箱 . 后者對于光杠和沿著光杠移動的絲杠是關(guān)鍵的 ,它在整個長度是關(guān)鍵的一部分 . 一個現(xiàn)代的車床通常在主軸箱之下位于一個快速變速的齒輪箱和經(jīng)過一列齒輪傳動的主軸 . 刀架被連接到絲杠和光杠而且能夠通過操作杠桿迅速簡單地選擇一系列的進(jìn)給 , 變速齒輪箱應(yīng)用于普通的車削、平面和螺紋的切削操作 . 因為那齒輪箱被連接到主軸上的 , 對于托板箱移動的距離可以被控制。 . 車床切斷工具 形狀和車床工具的幾何 尺寸根據(jù)車床應(yīng)用的目的而決定 . 車削刀具可以分為兩種主要的類型即外部的切削刀具和內(nèi)部的切削刀具 , 每一個這些小組包括刀具的有下列類型 : 車刀 . 車刀能用于精加工或者粗加工的工具 . 粗加工的車刀具有小的鼻子半徑用于大的切削用量 . 另一方面精加工的車刀具有大的鼻子半徑用于獲得最終需要的尺寸這個尺寸通過小的切削深度獲得高的表面質(zhì)量。粗車刀具有用右手或左手的兩種類型 ,根據(jù)進(jìn)給的方向而定 . 它們能有直的 , 彎的 , 或偏置的刀柄 . 平面車刀 . 平面車刀用于待加工的表面或者端面的平面加工 . 這些刀具有用左手邊操作 加工表面的和用右手邊操作加工表面的 . 這些表面通過刀具的橫向進(jìn)給實現(xiàn) , 和車削刀具相反的是 , 縱向進(jìn)給通常被應(yīng)用 . 切斷刀具 . 切斷刀具 ,有時叫做分離刀具 ,可用于切斷工件以及 / 或以機(jī)器制造外的凹槽 . 螺紋車到 . 螺紋車具有三角形的 , 正方形 , 或 梯形的刃口 , 取決于需要的螺紋的橫截面的樣式。同時 , ，這些刀具的面角度總是一定和那些螺紋現(xiàn)狀相同的 . 螺紋切削刀具的直刀柄用于外部的螺紋切削而偏置刀具用于外部螺紋的切削 . 成形車刀 . 成形車刀是特別用于加工特殊形式截面的加工刀具 ,與被以機(jī)器制造的希望工件的形 狀相反 . 高速鋼刀具通常是做成單獨的一塊整體和硬質(zhì)合金刀具或陶瓷刀具相反的是 , 它們是做成刀尖的形式 . 后者是由焊接的或者機(jī)械方式夾緊與刀柄構(gòu)成一個整體 . 圖 .11.2 指出了一系列后者的類型 ,這些包括碳化物頂尖、斷屑器、刀片，緊固螺 14 絲釘 (一個墊圈和一個螺釘 ) 和刀柄 . 當(dāng)做名字所說的那樣，斷屑器的功能是時不時的切斷切屑 ,如此避免長的帶狀切屑形成這些帶狀切屑在操作時可能會帶來問題 . 碳化物頂尖 ( 或陶瓷的頂尖 ) 可以有不同的形狀 , 根據(jù)他們應(yīng)用的機(jī)床操作 . 頂尖可以是一個整體或者是中央有 一個洞 ,根據(jù)這個頂尖是焊接還是用機(jī)械夾緊方式使其安裝在刀柄上。 車床操作 在下列的段落中 , 我們將討論能在傳統(tǒng)的車床上被運行的各種不同的機(jī)床操作 . 這個必須銘記于心 , 然而，現(xiàn)代的數(shù)控車床具有更多的功能 并且能做其他的操作 ,比如成形加工 , 舉例來說 . 下列各項是普通的車床操作 . 外圓車削 . 外圓車削是最簡單的和最通常的車床操作 . 工件每旋轉(zhuǎn)一周就在工件上產(chǎn)生一個圓心在車身軸線上的軌道 ； 這個動作的多次產(chǎn)生才能實現(xiàn)切削加工 . 加工的結(jié)果是一個具有很小螺距的螺旋線 . 結(jié)果 , 已加工表面是圓形的 . 軸向進(jìn)給是由刀架或者是小刀架提供 ,可用手動或自動化方式實現(xiàn) , 然而削減的深度由橫向進(jìn)給實現(xiàn) . 在粗車加工時，一般推薦大的切削深度 (從 0.25 到 6 毫米左右 , 取決于工件的材料 ) 并且會采取較小的進(jìn)給量 . 另一方面 , 非常小的進(jìn)給量 , 非常小切削深度 (小于 0.05 或 0.4 毫米 ), 和高的切削速度應(yīng)用于精加工 . 平面車削 . 平面加工的結(jié)果是一平表面這個表面既可以是整個端面或或者是軸間處的一個環(huán)形表面 . 在平面車削過程中，進(jìn)給量是由橫向進(jìn)給提供的，然而削減的深度是有刀架或者小刀架提供 的 . 平面車削可以從工件的外圓向中心也可以從工件的中心向外圓 . 很明顯這兩種加工都產(chǎn)生螺旋形的加工軌跡 . 通常，在平面加工過程中最好要夾緊刀架 , 因為切削力容易推動刀具 ( 當(dāng)然 , 整個的刀架 ) 遠(yuǎn)離工件 . 在大多數(shù)平面加工過程中，工件被夾緊在吸盤上或者工作臺上 凹槽切削 . 在切斷和切槽的加工中 ,只應(yīng)用刀具的橫向進(jìn)給 . 那切斷和切槽工具 , 在先前已經(jīng)討論過了 , 用過了 . 鉆孔和內(nèi)表面車削 . 鉆孔和內(nèi)表面車削是在工件內(nèi)表面上有鉆桿或者是適當(dāng)?shù)膬?nèi)表面切削刀具 , 如果最初的工件是實心的，必須先進(jìn)行鉆 孔加工 . 鉆孔刀具安裝在刀架上 , 而后刀架相對于工件進(jìn)行進(jìn)給 . 圓錐面車削 . 圓錐面車削是通過驅(qū)動刀具沿著與車床軸線方向不平行而是與軸線傾斜方向即想得到的圓錐角 . 下列各項是用圓錐面車削的不同的方法 : （ 1）旋轉(zhuǎn)小刀架上的刀盤使其達(dá)到半頂角的度數(shù) . 進(jìn)給是通過手動方式旋轉(zhuǎn)小刀架上的手柄方式完成的 . 這一個方法大多數(shù)應(yīng)用于較大的內(nèi)圓錐角和角大的外圓錐角切削 . （ 2）采用專用成形刀具 , 對非常短的錐形表面加工 . 工件的寬度一定要比刀具的 15 稍微小一點，而且工件通常被安裝在吸盤上或者在工作臺上 . 在這種 情形下 , 只有橫向進(jìn)給應(yīng)用于這種加工過程中而且刀架被夾緊到機(jī)器床身上 . （ 3）偏置尾座中心 . 這一個方法應(yīng)用于較長的和錐角較小（小于 8 度）的外圓錐面車削。 工件被裝在兩個頂尖之間 ； 然后尾座在垂直于車床主軸線移動距離 S. （ 4）采用錐面切削裝置 . 這一個方法應(yīng)用于車削較長的工件。 當(dāng)長度比小刀架長度還要大時 . 在如此的情況橫向進(jìn)給機(jī)構(gòu)和刀架完全脫離 ,然后橫向進(jìn)給由附加裝置提供 . 在這一個過程中 , 自動的軸向進(jìn)給能像往常一樣使用 . 這一個方法是為非常長的工件以及比較小的圓錐體角度 ,比如 8 度到 10 度。 車削螺紋 . 當(dāng)進(jìn)行螺紋切削的時候 , 軸向進(jìn)給必須保持恒定的速度 ,速度大小取決于工件工件轉(zhuǎn)速 (轉(zhuǎn) /每分 ) . 兩者之間的關(guān)系主要有切削螺紋的螺距決定 . 正如先前提到的那樣 ,通過絲杠切削螺紋自動產(chǎn)生的 ， 軸向進(jìn)給驅(qū)動刀架 。當(dāng)絲杠旋轉(zhuǎn)一周時刀架運動距離等于絲杠的螺距，因此，如果絲杠旋轉(zhuǎn)速度等于主軸旋轉(zhuǎn)速度（工件主軸）切削結(jié)果工件螺距等于絲杠螺距 絲杠螺距 工件轉(zhuǎn)速 = = 主軸和刀架的傳動比 工件螺距 絲杠速度 這個等式對于車床主軸和絲杠的傳動鏈的決定很有用具體的說也就是對傳動鏈中齒輪的選擇很有幫助 . 在螺紋切削加工過程中 , 相對較長的工件安裝在吸盤上或者在車床兩頂尖之間 . 使用的刀具的形狀必須與要切削螺紋輪廓非常精確 , 比如三角形的車刀必須用于切削三角形螺紋，以此類推。 滾花加工 . 滾花加工主要是一種成形加工方式，這種加工沒有切屑的產(chǎn)生 . 這種加工方法是用兩 個有粗銼式的表面的硬化滾軸壓在滾動工件上在工件表面上產(chǎn)生塑性變形。 滾花加工應(yīng)用于比較粗糙的外圓柱面 ( 或者圓錐面 ) ,通常用來做手柄 . 有時侯，表面僅僅用來做裝飾用 ； 而且有不同式樣滾花可供選擇 . 切削速度和進(jìn)給量 切削速度 , 通常由每分鐘表面的進(jìn)給量 (SFM)表示 , 是在一分鐘內(nèi)在工件的表面 (正在削減 )沿切削方向移動的數(shù)量 . 表面的切削速度和轉(zhuǎn) /每分之間的關(guān)系根據(jù)下列等式有 : SMF=3.14* DN 在這里： D = 工件的直徑 16 N = 轉(zhuǎn) /每分 表面的切削速度主要取決于加工工件的材料，刀具的材料 , 和通過手冊獲得的關(guān)于切削刀具的信息 . 通常 , SFM 指的是 100 當(dāng)切削冷壓鋼或低碳鋼時 ,當(dāng)較強(qiáng)硬的金屬時取 50 , 當(dāng)較軟材料取 2